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Cells-The Living Units

organisms arise spontaneously from garbage or other nonliving matter theory of spontaneous generation
when define cell properties are defining properties of life
activity of organism depends on both individual and collective activities of its cells
biochemical activities of cells are dictated by relative number of their specific subcellular structures principle of complementarity of structure and function
not highly differentiated biologically nor strictly adapted to a particular environment generalized cells
specialized cells are considered composite cells
fragile barrier; composed of phospholipids, cholesterol, & proteins; encloses cell contents; outer limiting cell membrane plasma membrane
internal to plasma membrane; intracellular fluid packed with organelles, small structures that perform specific functions cytoplasm
controls cellular activities & typically lies near cell's center nucleus
depiction of membrane (7-10nm) structure of cell, as phospholipid bilayers in which proteins are dispersed fluid mosaic model
many proteins, of plasma membrane, float in __ __ __, forming constantly changing mosaic patterns fluid lipid bilayer
forms basic fabric of plasma membrane; constructed largely of phosolipids with smaller amount of cholesterol & glycolipids lipid bilayer
refers to molecules, or portions of molecules, that interact with water and charged particles; lollipop-shaped phospholipid hydrophilic
refers to molecules, or portions of molecules, that interact only with uncharged, nonpolar molecules; made of two fatty acid chains hydrophobic
each lollipop-shaped __ has hydrophilic & __ that is hydrophobic head; tail
hydrophilic polar heads are attracted to inner & outer surfaces of plasma membrane, because main constituent of both intracellular & extracellular fluid
hydrophobic, nonpolar tails line up in __ of membrane center
property of phospholipids encourages biological membranes to self-assemble into closed, generally spherical, structures and reseal themselves quickly when torn self-orienting
plasma membrane is __ __ structure in constant flux dynamic fluid
lipid molecules of bilayer move freely __ __ membrane surface, side to side parallel
__ __ prevent lipid molecules from flip-flopping or moving from one phospholipid layer to other nonpolar interactions
differ in kinds and amounts of lipids they contain; variations important in determining local membrane structure & function inward- facing & outward-facing surfaces
majority of membrane phospholipids are __, condition which kins their tails (increasing space btwn them) & increases membrane fluidity unsaturated
lipid with one or more covalently attached sugars glycolipids
glycolipids are found only on __ plasma membrane surface, accounting for about 5% of total membrane lipid outer
sugar groups of glycolipid make that end of the molecule __, whereas __ __ tails are nonpolar polar; fatty acid
hydroxyl group of cholesterol is __ region and its fused ring system is __ region polar; nonpolar
cholesterol wedges its platelike __ __ btwn phospholipid tails, __ membrane while increasing __ of phospholipid & fluidity of membrane hydrocarbon rings; stabilizing; mobility
contained in outer membrane surface, 20%; dynamic assemblies of saturated phospholipids associated w/unique lipids called sphingolipids & lots of cholesterols lipid rafts
lipid rafts are __ __ and orderly, less fluid than rest of membrane, & can include/exclude specific __ to various extents more stable; proteins
lipid rafts are assumed to be __ __ for certain receptor molecules or for molecules needed for cell signaling concentrating platforms
make up about 1/2 of plasma membrane by mass & are responsible for most of specialized membrane functions proteins
firmly inserted into lipid bilayer have both hydrophobic & hydrophilic regions allowing them to interact both w/nonpolar lipid tails buried in membrane & w/water inside/outside cell integral proteins
some integral proteins __ from one face only protrude
most integral proteins, that span entire width of membrane & protrude on both sides transmembrane proteins
most __ proteins are involved in transport, although some are __ transmembrane; enzymes
some transmembrane proteins cluster together forming __/__, through which small, water-soluble molecules/ions can move channels; pores
when transmembrane proteins form channels, allowing small, water-soluble molecules/ions to pass it bypasses the __ __ of membrane lipid part
__ __ __ act as carriers that bind to substance & then move it through membrane some transmembrane proteins
some transmembrane proteins are receptors for hormones or other chemical messengers & relay messages to cell interior; process is called signal transduction
related to, located in, or constituting an outer boundary; attach rather loosely only to integral proteins & are easily removed w/out disrupting membrane peripheral proteins
peripheral proteins include network of __ that help support membrane from cytoplasmic side filaments
some __ proteins are enzymes peripheral
some peripheral proteins are __ proteins involved in mechanical functions, i.e. changing cell shape during cell division & muscle cell contraction motor
some proteins float freely, but in particular peripheral proteins are __ in their movements because they are tethered to intracellular structures that make up __ restricted; cytoskeleton
many of proteins that abut extracellular fluid are __ w/branching sugar groups glycoproteins
glycocalyx is layer of __ facing glycoproteins on cell's plasma membrane that determines __ __ externally; blood type
glycocalyx involved in cellular interactions of fertilization, embryonic development, & immunity; acts as adhesive btwn cells glycocalyx
term glycocalyx means sugar covering
glycocalyx used to describe fuzzy, sticky, __ area at cell surface carbohydrate-rich
glycocalyx that clings to each cell's surface is enriched by __ & __ secreted by cell glycolipids; glycoproteins
glycocalyx provides highly specific __ __ by which approaching cells recognize each other biological markers
cell of immune system identify __ by binding to certain membrane glycoproteins in __ glycocalyx bacterium; bacterial
cancer cell's glycocalyx may change continuously, allowing it to keep ahead of immune system __ mechanism and avoid __; example of homeostatic imbalance recognition; destruction
glycoproteins in glycocalyx, wavy contours of membranes adjacent cells (tongue-&-groove fashion), & special membrane junctions formed are three factors that act to bind cell together
most important factor securing cells together are junctions
area where plasma membranes of adjacent cells are fused; series of integral protein molecules in plasma membranes of adjacent cells tight junctions
series of integral proteins molecules in tight junctions include occludins & claudins
when series of integral proteins molecules, in tight junctions, fuse together they form __ junctions that encircle cell impermeable
tight junctions help prevent molecules from from passing through __ __ btwn adjacent cell extracellular space
although called impermeable junctions, some tight junctions __ & may allow certain types of ions to __ leak; pass
cell junction composed of thickened plasma membranes joined by filaments; binding bodies; anchoring junctions desmosomes
mechanical couplings scattered like rivets along sides of abutting cells that prevent their separation anchoring junctions
button-like thickening on cytoplasmic face of each plasma membrane plaque
thin linker protein filaments that extend from plaques & fit together with adjacent cells, like teeth of a zipper in intercellular space cadherins
intermediate filaments forming past of cytoskeleton keratin filaments
keratin filaments, of desmosomes, extend from __ side of plaque across width of cell to anchor plaque on cell's opposite side cytoplasmic
desmosomes not only bind neighboring cells together, but also contribute to continuous __ __ of strong "guy-wires" internal network
arrangement of desmosomes continuous internal network, distributes __ throughout cellular sheet & reduces chance of tearing when subject to pulling forces tension
desmosomes are abundant in tissues subjected to great __ __, such as skin & heart muscle mechanical stress
communicating junction/passageway between 2 adjacent cells; formed by transmembrane proteins called connexons gap junction
hemichannel supplied by 1 protein cell, on 1 side of gap junction; connexon
assembly of six protein hemichannels, supplied by cell on 1 side of gap junction connexin
ions, simple sugars, & other small molecules pass through water-filled channels from 1 cell to next, acting as conduit btwn cytoplasm & extracellular space connexon/connexin
gap junctions are present in __ __ tissues, where ion passage from cell to cell helps __ their electrical activity & contraction electrically excitable; synchronize
fluid between the cells; derived from blood; contains amino acids, sugars, fatty acids, vitamins, regulatory hormones, neurotransmitters, salts & waste products interstitial fluid (IF)
to stay healthy each cell must __ from the IF exact amounts of substance it needs at specific times extract
allows some substance to pass while excluding others; keeps undesirable substance out while allowing nutrients in; keeps valuable cell proteins & other substance in cell, but allows waste out selectively/differentially permeable membrane
substances cross membrane without any energy input from cell passive process
membrane transport processes for which ATP is required, e.g., solute pumping and endocytosis active process
characteristic of healthy, intact cells selective permeability
when cell/plasma membrane severely dmgd, membrane becomes __ to virtually everything and substance flow into/out of cell freely; causes homeostatic imbalance permeable
when someone is severely burned, precious fluids, proteins, and ions, "weep" from dead & dmgd cells; this is an example of a(n) __ __ membrane becoming a(n) __ membrane selectively permeable; permeable
diffusion & filtration; two main types of __ transport passive
spreading of particles in gas or solution w/movement toward uniform distribution of particles diffusion
diffusion is tendency of molecules/ions to move from area where they are in __ concentration to area where they are in __ concentration higher; lower
difference in the concentration of a particular substance between two different areas concentration gradient
greater difference in concentration of diffusing molecules and ions btwn 2 areas, more collisions occur & faster __ __ of particles net diffusion
driving force of diffusion is kinetic energy
speed of diffusion is influenced by molecular __ & __ size; temperature
in a closed container, diffusion eventually reaches equilibrium, with molecules moving equally in all directions causing a __ __ of molecules uniform mixture
movement of ions across cell membranes & movement of neurotransmitters btwn two nerve cells examples of diffusion
__ __ is almost impossible to see pure diffusion
plasma membrane is physical barrier to free diffusion because of its hydrophobic core
molecule will diffuse through membrane if molecule is __ __ lipid soluble
molecule will diffuse through membrane if molecule is small enough to pass through membrane channels
molecule will diffuse through membrane if molecule is assisted by a(n) __ __ carrier molecule
unassisted diffusion of lipid-soluble molecules or very small particles simple diffusion
unassisted diffusion of solvent (usually water) through a selectively permeable membrane osmosis
assisted diffusion is known as facilitated diffusion
in simple diffusion, these substances diffuse directly through the lipid bilayer; these incl oxygen, carbon dioxide, & fat-soluble vitamins nonpolar & lipid-soluble substances
oxygen concentration is always higher in blood than in tissues, therefore oxygen always diffuses __ __ __ from blood to tissue down concentration gradient
carbon dioxide is in higher concentration within tissues than blood, therefore it diffuses __ __ __ from tissue into blood down concentration gradient
glucose/other sugars, some amino acids, & ions are unable to pass through lipid bilayer, therefore passive process of __ diffusion facilitated
facilitated diffusion, allows substance unable to pass through lipid bilayer, to be transported by binding to __ __ in membrane that ferries them across protein carriers
facilitated diffusion, allows substance unable to pass through lipid bilayer, to be transported by moving through water-filled __ __ protein channels
transmembrane integral protein that shows specificity for molecules of certain polar substance/class of substances, too lrg to pass through membrane channels; i.e. sugars & amino acids carriers
most popular model for action of carriers, indicates change in shape of carrier allowing it to envelop & then release substance, shielding it en route from non polar regions of membrane
__ __, of carriers, is moved from one face of membrane to other by changes in conformation of carrier protein binding site
one of spatial arrangements of atoms in molecule that can come about through free rotation of atoms about single chemical bond conformation
glucose moves down its concentration gradient, just as in simple diffusion, when transported by __ __ diffusion carrier-mediated facilitated
normally in higher concentration in blood than in cells, where its rapidly used for ATP synthesis glucose
glucose transport within body is typically __, into the cells unidirectional
limited by numbers of protein carrier present carrier-mediated transport
when all glucose, carrier-mediated transport, carriers are __ they are said to be saturated & glucose transport is occurring at __ __ engaged; maximum rate
transmembrane protein that forms aqueous pore, allowing substances to move from one side of membrane to other channels
exist within channels, and channels are selective due to pore size and charges of amino acids lining channel binding/association sites
channels always open & simply allow ion/water fluxes according to concentration gradients leakage channels
some channels are gated & controlled, __ or __, by various chemical or electrical signals open; closed
many channels can be inhibited by certain molecules, show __, and tend to be specific saturation
substances moving through channels also follow the concentration gradient, always moving down the gradient
when substance crosses membrane by simple diffusion, rate of diffusion is not controllable because __ __ of membrane is not immediately changeable lipid solubility
rate of facilitated diffusion is __ because permeability of membrane can be altered by __ activity/number of individual carriers or channels controllable; regulating
vitally important to cellular homeostasis; passive transport by diffusion, either simple/facilitated, represents tremendous saving of cellular energy oxygen, water, glucose, & various ions
if oxygen, water, glucose, & various ions had to be transported __, cell expenditures of ATP would __ exponentially actively; increase
even though water is highly polar, it passes via osmosis through __ __ lipid bilayer
transmembrane proteins that form water channels aquaporins (AQPs)
water moves freely & reversibly through __ __ constructed by AQPs water-specific channels
AQPs are particularly abundant in RBCs & cells involved in __ __, such as kidney tubules water balance
osmosis occurs whenever __ __ differs on 2 sides of membrane water concentration
if distilled water present on both side of selectively permeable membrane, no __ __ occurs, even though water molecules move in both direction through membrane net osmosis
solute concentration on 2 sides of membrane differs, water concentration __ differs
extent to which water's concentration is decreased by solutes depends on __ not on __ of solute particles number; type
one molecule or one ion of solute displaces one water molecule
number of solute particles present in 1 liter of a solution osmolarity
when equal volumes of aqueous solutions of different osmolarity are separated by membrane that is permeable to all molecules in system, net diffusion of __ occurs; each moving __ its concentration gradient both; down
pressure of fluid in a system hydrostatic pressure
measure of tendency of water to move into more concentrated solution osmotic pressure
higher amount of nondiffusible, non penetrating, solutes in cell higher the __ pressure & greater __ pressure that must be developed to resist further net water entry osmotic; hydrostatic
major changes in hydrostatic/osmotic pressure do not occur in living animal cells because they lack rigid cell walls
cause animal cells to swell or shrink, due to net water gain/loss, until wither solute concentration is same on both side of membrane, or membrane is stretched to breaking point osmotic imbalances
ability of solution to change shape/tone of cells by altering their internal water volume tonicity
of, relating to, or exhibiting equal osmotic pressure isotonic
cells exposed to __ __ retain their normal shape, & exhibit not net loss/gain of water isotonic solutions
body's __ fluids & most __ solutions are isotonic extracellular; intravenous
solutions with higher concentration of nonpenetrating solutes than seen in cell hypertonic
cells immersed in __ __ lose water and shrink hypertonic solutions
having the margin or surface cut into rounded scallops; effect of immersion in hypertonic solutions crenate
solutions more dilute than cells hypotonic
cells placed in __ __ plump up rapidly, as water rushes into them hypotonic solutions
represents most extreme example of hypotonicity, because contains no solutes, water continues to enter cells until they finally burst distilled water
bursting of a cell lyse
tonicity is based on how solute affects cell volume, which depends on solute __ & solute __ of plasma membrane concentration; permeability
osmolarity is expressed as __ per liter osmoles
1 osmole = to 1 mole of __ molecules nonioniziting
osmosis is extremely important in determining distribution of water in various __ __ of body fluid-containing compartments
osmosis continues until osmotic & hydrostatic pressure acting at membrane are equal
water is forced out of capillary blood by __ pressure of blood against capillary wall, but presence in blood on solutes that are too lrg to cross capillary membrane draws water back into __; resulting in very little net loss of __ __ hydrostatic; blood-stream; plasma fluid
simple diffusion & osmosis occurring directly through plasma membrane are not __ processes selective
simple diffusion & osmosis occurring directly through plasma membrane, whether molecule can pass through membrane depends chiefly on __ or __ in lipid, not on its unique structure size; solubility
facilitated diffusion is often __ __ highly selective
hypotonic solutions are sometimes infused in edematous patients, to draw excess water out of __ __ and move it into __ so it can be eliminated in kidneys extracellular space; bloodstream
hypotonic solutions may be use to __ __ of extremely dehydrated patients rehydrate tissues
requires carrier proteins that combine specifically & reversibly with transported substance active transport
enzyme-like protein carrier that mediates active transport of solutes, such as amino acids & ions, uphill against concentration gradients solute pumps
solutes moved by solute pumps, most importantly ions such as Na+, K+, & Ca2+
active transport processes are distinguished according to their source of energy
energy to do work comes directly from hydrolysis of ATP primary active transport
driven by indirectly by energy store in ionic gradients created by operation of primary active transport pumps secondary active transport
secondary active transport systems are all __ __; that is, they move more than one substance at a time coupled systems
if 2 transported substances, in 2ndary active transport system, are moved in same direction symport system
in 2ndary active transport system, if transported substances wave to each other as they cross the membrane in opposite directions antiport system
in primary active transport, hydrolysis of ATP results in __ of transport protein phosphorylation
phosphorylation caused protein to change __ in such a manner that it __ bound solute across membrane shape; pumps
incl calcium & hydrogen pumps, but most investigate example is operation of sodium-potassium pump primary active transport systems
primary active transport system that simultaneously drives Na^+ out of cell against steep gradient & pumps K^+ back in sodium-potassium pump
carrier enzyme in sodium-potassium pump Na+-K+ ATPase
concentration in body cell is 10 times higher that outside K+
concentration in body cell is 10 lower higher that outside Na+
the __ __ __ of K+ vs Na+, are essential for excitable cells, like muscle & nerve cells, to function normally ionic concentration difference
leak slowly but continuously through leakage channels in plasma membrane along their concentration gradient, & cross more rapidly in stimulated muscle & nerve cells Na+ & K+
operates more/less continuously as an antiporter Na+ -K+ pump
maintained by Na+ -K+ pump, underlie most primary & secondary active transport of nutrients & ions; crucial for cardiac & skeletal muscle & neuron functions electrochemical gradients
can indirectly drive secondary active transport of several other solutes single ATP-powered pump
by Na+ -K+ pump, moving sodium across plasma membrane against concentration gradient, pump __ __ in ion gradient store energy
substance pumped uphill/against concentration gradient across membrane can __ __ as it leaks back - propelled downhill along its concentration gradient do work
in Na+ -K+ pump: as sodium moves back downhill, into cell w/help of carrier proteins, other substance are __ by common carrier, a symport system cotransported
both cotransported substances (in Na+ -K+ pump: as sodium moves back downhill) move __ because energy for this type of transport is concentration gradient of the ion passively
can be used in symport systems, or used to drive antiport systems ion gradients
sugars, amino acids, and many ions are cotransported into cells lining small intestines; this is example of symport system in secondary active transport
regulation of intracellulare pH by using sodium gradient to expel hydrogen ions, is an example of antiport system in secondary active transport
whether energy is provided directly, in primary active transport, or indirectly, in secondary active transport, each membrane pump/cotransporter transports __ __ substances only; specific
because membrane pump/cotransporter transports only specific substances, active transport systems provide way for cell to be very __ in cases where substances cannot pass by __ selective; diffusion
pocket of embryonic tissue that is beginning of an organ; membranous sac vesicles
movement of large particles & macromolecules across a plasma membrane vesicular transport
mechanism by which substances are moved from cell interior to extracellular space as secretory vesicle fuses w/plasma membrane exocytosis
means by which fairly large extracellular molecules or particles enter cells, e.g., phagocytosis, pinocytosis, receptor-mediated endocytosis endocytosis
moving substances into, across, & then out of cells transcytosis
moving substances from one are/organelle in cell to another substance/vesicular trafficking
vesicular transport processes are energized by __, or in some cases another energy-rich compound, GTP - guanosine triphosphate ATP
all forms of vesicular transport involve assortments of __ vesicles of 3 types, with some exceptions, all are __ by membrane receptors protein-coated; mediated
protein-coated vesicles provide main route for __ & __ of bulk solids, most macromolecules, & fluids endocytosis; transcytosis
often hijacked by pathogens seeking entry into a cell protein-coated vesicles
in endocytosis stage1, substance to be taken into cell progressively enclosed by infolding portion of plasma membrane called coated pit
protein coating that forms on cytoplasmic side of coated pit, in endocytosis clathrin
clathrin & some accessory proteins; acts both in cargo selection & in deforming membrane to produce vesicle clathrin coat
in endocytosis stage2, vescile __ detaches
in endocytosis stage 3, __ __ are recycled back to plasma membrane coat proteins
in endocytosis stage4, __ __ then typically fuse with endosome uncoated vesicle
processing and sorting vesicle endosome
in endocytosis stage5, some membrane components & receptors of fused vescile may be recycled back to plasma membrane in __ __ transport vesicle
in endocytosis stage6, remaining contents of vesicle may, __ with lysosome, or be transported completely across cell & released by __ on opposite side combine; exocytosis
specialized cell structure containing digestive enzymes where digested substance is degraded or released lysosome
transcytosis is common in __ cells lining blood vessels because it provides quick means to get substance from blood to interstitial fluid endothelial
based on nature & quantity of material taken up & means of uptake, 3 types of endocytosis that use clathrin-coated vesicles are recognized phagocytosis, pinocytosis, & receptor-mediated endocytosis
type of endocytosis in which cell engulfs relatively lrg/solid material; e.g. bacteria, dead cell debris, foreign substances engulfed by cells phagocytosis
in phagocytosis, when particle binds to receptors on cell's surface, __ __called pseudopods form & flow around particle & engulf it cytoplasmic extensions
formed as a result of phagocytosis; vesicle containing engulfed material that fuses w/lysosome & its contents are digested phagosome
in most cases phagosome fuses with __ & its contents are digested lysosome
in human body, macrophages & certain WBCs are only cells that are experts at phagocytosis, called phagocytes
flowing movement of the cytoplasm, into temporary pseudopods, of a phagocyte allowing them to creep along; "changing shape" amoeboid motion
cells have the same __ parts basic
plasma membrane, cytoplasm, nucleus, are all basic parts of cells
cell membrane lipid bilayer w/proteins dispersed in it meaning it is a(n) phospholipids bilayer
in cell membrane, __ float in the lipid bilayer proteins
__ recognizes an ovum by its glycocalyx sperm
glycocalyx forms cell __ molecules & __ adhesion; receptors
transport, receptors, forming cell junctions are all functions of membrane proteins
function of membrane proteins includes __ __ (glycocalyx) cell-cell recognition
function of membrane proteins includes attaching to cytoskeleton & extracellular matrix to help maintain cell shape
minute finger-like extensions of plasma membrane microvilli
microvilli are example of __ of plasma membrane specialization
microvilli increase __ __ surface area
microvilli are found on __ __ i.e. kidney tubule cells & small intestinal cells absorptive cells
example of desmosomes are heart muscle cells
example of gap junctions are heart muscle, smooth muscle
example of tight junctions are between epithelial lining of digestive tract
lipids, CO2, O2 pass through plasma membrane via simple diffusion
glucose, amino acids pass through plasma membrane via protein specific carrier in carrier-mediated facilitated diffusion
vesicular transport requires ATP
used for hormone, secretion, neurotransmitter release, mucous secretion exocytosis
infolding plasma membrane pinches off droplet of extra cellular fluid & dissolved molecules- vesicle fuses w/endosome; occurs in most cells, esp. cells of intestines pinocytosis
pinocytosis means cell drinking
main mechanism for endocytosis & transcytosis of most macromolecules; substances bind to specific receptors on plasma membrane, vesicle formed; used for taking in some enzymes, hormones, cholesterol attaches to lipoproteins receptor-mediated endocytosis
phagosome fuse with lysosome
phagocytosis is process used by __ & __ to protect body macrophages; neutrophils
exist across membranes of all cells of the body, resulting from separation of oppositely charged ions across membrane electrical potential/voltage
in resting state cells have resting membrane __ ranging from 50-100 mV potential
important in excitable tissues, such as nerve/muscle cells, where rapid changes are used to transmit impulses; typically ranges from -50 to -100 mV depending on cell type resting membrane potential
resting membrane potential can also be considered action potentials
the ionic concentration difference of K+ vs Na+, are essential for excitable cells, like muscle & nerve cells, for all body cells to maintain their normal __ __ fluid volume
resting membrane potential is created by concentration of K+ more __ cells while that of Na+ is more __ cells inside; outside
in __ membrane __, main factor is movement of K+ from inside to outside cell through leak channels (down concentration gradient) creating an electronegativity inside resting; potential
in resting membrane potential, some diffusion of Na+ from outside-inside hardly makes difference to electronegativity because __ __ are 100x more permeable to K+ under resting conditions leak channels
pumps out 3 Na+ for every 2 K+ pumped in; resulting in further loss of +charge from inside membrane, adding to electronegativity Na+- K+ pump
have specificity for particular ligands; i.e., hormones, neurotransmitters membrane receptor proteins
signaling chemicals that bind specifically to membrane receptors; most hormones, neurotransmitters, & paracrines ligands
in membrane receptor, __ __ initiates specific/multiple cellular responses ligand binding
common type of membrane receptors are G __ receptors protein-linked
exert their effect indirectly through G proteins, which acts as middleman/relay to activate/inactivate membrane-bound enzyme/ion channel G protein-linked receptors
cellular material surrounding the nucleus & enclosed by plasma membrane; contains the cytosol, organelles & inclusions cytoplasm
largely water w/dissolved protein, salts, sugars, & other solutes cytosol
mitochondria, peroxisomes, lysosomes, rough/smooth ER, & Golgi apparatus membranous cytoplasmic organelles
cytoskeleton, centrioles, & ribosomes nonmembranous cytoplasmic organelles
double membrane structure w/shelf-like cristae mitochondria
mitochondria are __ __ in metabolically active cells like kidney/liver more numerous
mitochondria contain __ __ DNA/RNA their own
mitochondria provide majority of a cell's ATP via __ cellular respiration aerobic
sites of protein synthesis; composed of proteins & rRNA; each has 2 subunits ribosomes
__ __ synthesize soluble proteins free ribosomes
located on RER; synthesize proteins to be incorporated into cells membranes/for export membrane-bound ribosomes
system of interconnected tubes & parallel membranes enclosing cristae; is continuous w/nuclear membrane endoplasmic reticulum
external surface studded w/ribosomes; manufacture all secreted proteins & proteins for cell membranes Rough ER
RER __ __ in antibody producing plasma cells, secretory cells (pancreatic cells), liver cells which product plasma proteins more abundant
enzymes of __ involved with lipid metabolism & cholesterol synthesis breakdown of glycogen (liver) SER
enzymes of SER involved with synthesis of __ __, e.g. testosterone in testes steroid-based hormones
enzymes of SER involved with __ reticulum in skeletal & cardiac muscle cells sarcoplasmic
enzymes of SER involved with __ of drugs (liver & kidneys), detoxification
role of calcium ion storage & release in muscle contraction, in skeletal & cardiac muscles sarcoplasmic reticulum
stacked, flattened membranous sacs & tiny vesicles; functions in modification & packaging of proteins Golgi apparatus
when transport vesicles from RER fuse w/Golgi apparatus, proteins are __ modified
Golgi apparatus - proteins __ in vesicles, secretory vesicles move to plasma membrane, then are __ by exocytosis packaged; discharged
spherical membranous bags of digestive enzymes (acid hydrolases); digest ingested bacteria, viruses, & toxins; degrade worn out organelles lysosomes
lysosomes are __ in phagocytes abundant
lysosomal rupture __ __ autolysis results in
self digestion of the cell autolysis
system includes nuclear envelope, SER, RER, transport vesicles, Golgi apparatus, lysosomes, & plasma membrane endomembrane system
parts of endomembrane system work together to produce/export __ molecules & __ harmful substances biological; degrade
membranous sacs containing oxidase & catalase; detoxify harmful/toxic substances; numerous in liver & kidney cells peroxisome
peroxisomes __ dangerous free radicals neutralize
highly reactive chemicals w/unpaired electrons (i.e. O2-) that can damaged cell components free radicals
hollow tubes made of spherical protein tubulin; determine shape of cell & distribution of organelles; radiate from centrosome microtubules
microtubules, microfilaments, & intermediate filaments __ __ the cytoskeleton make up
strands of protein actin; involved in cell motility, muscle contraction, endocytosis, & exocytosis; 7nm microfilaments
tough, protein fibers; resist pulling forces on cell & help form desmosomes; 10nm intermediate filaments
paired, consisting of microtubules; located in centrosome near nucleus; form bases of cilia & flagella centrioles
generated microtubules for mitotic spindle during cell division centrosome
nucleus consists of nuclear envelope, nucleolus, & chromatin
gene-containing control center of cell; contains instructions for building nearly all body's proteins nucleus
most cells have __ nucleus one
referring to nucleus, skeletal muscle cells & osteoclasts are __ multinucleate
referring to nucleus, mature RBCs are anulcleate
selectively permeable double membrane barrier containing nuclear pores; outer membrane continuous w/RER & studded w/ribosomes nuclear envelope
nuclear envelope: through __ __ protein molecules are imported from cytoplasm nuclear pores;
nuclear envelope: through nuclear pores RNA __ __ nucleus exported from
nuclear envelope encloses jelly-like __ nucleoplasm
dark-staining spherical bodies w/in nucleus; site of assembly of 2 types of ribosomal subunits nucleoli
in nucleoli, 2 types of ribosomal subunits each consist of __ & __ rRNA; proteins
in nucleoli, ribosomal subunits leave through nuclear pores, to form __ ribosomes functional
nucleoli are __ in cells making a large amount of proteins larger
make up is: 30% DNA, 60% histone proteins, 10% RNA; arranged in units called nucleosomes; 2 varieties consists of extended & condensed chromatin
active chromatin that dictates protein synthesis extended chromatin
inactive chromatin forms chromosomes when nucleus starts to divide condensed chromatin
units within chromatin, made of arrangements of 8 histone proteins & 2 winds of the DNA nucleosomes
series of changes cell goes through from time it is formed until it reproduces via interphase cell cycle
stage of interphase when metabolic activity & growth, centrioles starts to replicate G1 (gap 1) phase
interphase consists of subphases: G1, S, G2
stage of interphase when DNA replication takes places S (synthetic) phase
stage of interphase when cell prepares for division; enzymes & proteins synthesize G2 (gap 2) phase
1 of 2 major periods in cell life cycle; includes period from cell formation to cell division interphase
term interphase reflects idea of resting phase of cell through its meaning of stage __ cell divisions between
during interphase cell is carrying out all its routine activities, only "resting" from __ dividing
metabolic or growth phase would be __ __ name for interphase more appropriate
consists of distinct events: mitosis and cytokinesis M (mitotic) phase
process during which chromosomes are redistributed to 2 daughter nuclei; division of nucleus; continuous process w/one stage merging smoothly to next mitosis
mitosis __ __ prophase, metaphase, anaphase, and telophase consists of
division of cytoplasm that occurs after cell nucleus has divided; division of cytoplasm cytokinesis
movement -kines
thread mit-
-osis process
1st stage mitosis prophase
2nd stage mitosis metaphase
3rd stage mitosis anaphase
final phase mitosis telophase
mitosis in human cells generally last about __ __, or less, from start to finish an hour
in DNA replication, before a cell can __ DNA has to be replicated, which occurs in S phase divide
in DNA replication, once DNA is replicated, DNA helices begin __ from nucleosomes unwinding
in DNA replication, during the DNA unwinding process, helicases untwists __ __ & __ DNA into two strands double helix; separates
in DNA replication, once DNA unwound, each nucleotide strand serves as __ for building new __ strand template; complementary
in DNA replication, __ __used to begin DNA synthesis RNA primers
in DNA replication, __ __ continues from RNA primer & adds complementary nucleotides to template DNA polymerase
in DNA replication, DNA polymerase, only works in __ __ once direction
__ __, of DNA polymerase, is synthesized continuously leading stand
__ __, of DNA polymerase, is synthesized in segments in opposite direction, then joined w/leading strand lagging strand
in DNA replication, 2 __ __ are formed, each having 1 old & new strand DNA molecules
in DNA replication, histones are __ from cytoplasm, then __ w/DNA forming 2 chromatin strands imported; associate
in DNA replication, chromatin untied by __; condensed to form __ centromere; chromatids
in DNA replication, chromatids __ __ until cell enters anaphase remain attached
dell division is essential for __ growth & __ repair body; tissue
continuously dividing cells e.g. intestinal epithelium, skin; cells that can be stimulated to divide e.g. liver cells; cells that cannot divide e.g. neurons, cardiac muscle & skeletal muscle cells 3 populations of cells according to their ability to replicate
in cytokinesis, __cytoplasm is pinched into 2 parts after mitosis ends- two __ cells cytoplasm; daughter
chromatin condenses into chromosomes, each appears as sister chromatid held by centromere; nucleoli disappear; centriole pairs separate from each other; microtubules lengthen to form mitotic spindle early prophase
nuclear fragments & membrane disappears; centrosomes at opposite poles; microtubules pull each chromosome from both poles late prophase
in metaphase, chromosomes cluster at __ of cell w/their __ at equator of spindle middle; centromeres
arrangement of chromosomes in plane midway between 2 poles is called metaphase plate
in anaphase, centromeres of chromosomes __ split
in anaphase, once chromosomes split, each chromosome __ __ a pole by microtubules pulled toward
in anaphase, chromosomes look __ V-shaped
in telophase, chromosomes have moved to __ __ opposite poles
in telophase, chromosomes __ & become thread-like __ uncoil; chromatin
in telophase, new nuclear membrane formed from __ __ rough ER
in telophase, nucleoli that disappeared in early prophase, __ reappear
in telophase, __ spindle appears mitotic
in telophase, cytokinesis __ cell division into 2daughter cells completes
in protein synthesis, 1 gene carries instruction for creating one __ chain polypeptide
in protein synthesis, 1 DNA base triplet codes for one __ __ amino acid
in protein synthesis, role of RNA includes: __, __, & __ mRNA; rRNA; tRNA
in protein synthesis, carries genetic info from DNA to ribosomes mRNA
in protein synthesis, is component of ribosomes rRNA
in protein synthesis, loads up w/amino acids & base pairs w/the codons of mRNA at ribosome for synthesis tRNA
in protein synthesis, involves transfer of info from DNAs gene base sequence to complimentary base sequence of mRNA transcription
in protein synthesis during transcription, this binds to DNA & unwinds 16-18 base pairs at a time RNA polymerase
in protein synthesis during transcription, RNA polymerase adds complementary __ __ on DNA template strand; other DNA strands is coding RNA nucleotides
in protein synthesis when transcription stops, mRNA strand __ __ DNA pulls off
3 base sequence of mRNA corresponding to a DNA base triplet codon
process in which DNA base sequence is translated into amino acid sequence for protein synthesis translation
in protein synthesis during translation, once __ is made, it leaves nucleus through the nuclear pores, enters cytoplasm & attaches to __ small subunit mRNA; ribosome
in protein synthesis during translation, __ __ initiator tRNA binds to start codon of mRNA (its anticodon base pairs) on ‘P’ site of ribosome methionine carrying
in protein synthesis during translation, once methionine carrying initiator tRNA binds to start codon of mRNA on ‘P’ site of ribosome, large __ __ binds to this complex forming a(n) __ __ ribosomal unit; functional ribosome
in protein synthesis during translation, 2nd tRNA binds to ‘A’ site on __, matching w/next 3bases on __ ribosome; mRNA
in protein synthesis during translation, amino acid carried by 2nd tRNA binds to __, the latter separating from its __ which moves to ‘E ‘ site & exits methionine; tRNA
in protein synthesis during translation, polypeptide chain __ till a stop codons is reached __ translation elongates; ending
pinocytosis is also called fluid-phase endocytosis
receptors for receptor-mediated endocytosis are __ __ __ that bind only certain substances plasma membrane proteins
in receptor-mediated endocytosis, receptors & attached molecules are __ in clathrin-coated pit internalized
enzymes, insulin & other hormones, low-density lipoproteins (i.e. cholesterol attached to transport protein), & iron are all substances take up by receptor-mediated endocytosis
flu viruses, diphtheria, & cholera toxins use receptor-mediated endocytosis to enter & attack our cells
tubular or flask-shaped inpocketings of plasma membrane seen in many cell types; capture specific molecules (folic acid, tetanus toxin) from extracellular fluid in coated vesicles & participate in from forms of transcytosis caveolae
caveolae are involved in unique kind of receptor-mediated endocytosis called __ potosis
caveolae are __ than most vesicles & their cage-like protein coat is __ & compose of caveolin smaller; thinner
integral membrane proteins that are principal components of caveola membranes; believed to act as scaffolding for assembly of signaling complexes caveolin
caveolae are closely associated w/lipid rafts that are platforms for __ proteins, receptors for hormones and enzymes involved in cell __ G; regulation
caveolae vesicles appear to provide sites for cell __ & cross talk btwn __ pathways signaling; signaling
1 of macromolecular protein complexes, composed of 7subunits & present in cytosol, that are assembled to form coat of vesicles that transport proteins btwn cisternae of Golgi complex & btwn Golgi complex & ER coatomer proteins
coatomer proteins used in most types of intracellular vesicular trafficking which transport substances btwn organelles COP1 & COP2
typically stimulated by cell-surface signal such as binding of hormone to membrane receptor or change in membrane voltage, accounts for hormone secretion, neurotransmitter release, mucus secretion, & in some cases ejection of wastes process of exocytosis
in exocytosis, substance to be removed from cell is 1st enclosed in __ __ sac called vesicle protein-coated membranous
in exocytosis, once substance to be removed is enclosed in vesicle, vesicle then migrates to plasma membrane, fuses with it, & then __, spilling sac contents, __ of cell ruptures; out
exocytosis involves __ process in which transmembrane proteins on vesicles called __ recognize certain plasma membrane proteins, called __ & bind with them v-SNAREs; t-SNAREs
binding of v-SNAREs & t-SNAREs causes membranes to __ together & fuse, rearranging lipid monolayers w/out mixing them corkscrew
membrane material added by __ is removed by __, the reverse process exocytosis; endocytosis
voltage across plasma membrane membrane potential
electrical potential energy resulting from separation of oppositely charged particles voltage
in cells, oppositely charged particles are __, & barrier that keeps them apart is __ __ ions; plasma membrane
because of resting membrane potential all cells are said to be __ polarized
a minus side before voltage, of a cell, indicates that the __ of cell is negative compared to its __ inside; outside
resting membrane potential voltage, or charge separation, exists __ __ the membrane only at
if all the - & + charged in cytoplasm were add up, would find cell interior is __ __ electrically neutral
+ & - charges in extracellular fluid __ each other out __ balance; exactly
resting membrane potential comes about because, diffusion causes ionic imbalances that __ membrane, & active transport processes __ that membrane potential polarize; maintain
resting membrane potential is determined mainly by __ __ of K+ & by __ permeability of plasma membrane to K+ & other ions concentration gradient; differential
K+ & protein anions __ inside body cells predominate
extracellular fluid contains relatively more __, largely balanced by __ Na+; Cl-
unstimulated plasma membrane is somewhat permeable to K+ because of __ __, but impermeable to protein __ leakage channels; anions
combined difference in concentration & charge; influences distribution & direction of diffusion of ions electrochemical gradients
ions diffuse according to __ gradients, thereby recognizing effect of both electrical & __ (chemical) forces electrochemical; concentration
although diffusion of K+ across plasma membrane is aided by membrane's greater __ to it & by ion's concentration gradient, its diffusion is resisted somewhat by __ __ on cell exterior permeability; positive charge
Na+ is drawn into cell by __ __ gradient, & limiting factor is membrane's relative __ to it steep electrochemical; impermeability
upsetting resting membrane potential by __ opening of Na+ & K+ channels in plasma membrane is normal means of __ neurons & muscle cells transient; activating
whether cells interact directly/indirectly the glycocalyx is __ __ always involved
best understood of participating glycocalyx molecules fall into 2 large families cell adhesion molecules & plasma membrane receptors
another group of membrane proteins, which are important in cells that respond to electrical signals voltage-sensitive channel proteins
cell surface glycoproteins that mediate intercell adhesion in body; cadherins, integrins cell adhesion molecules (CAMs)
sticky glycoproteins (cadherins, integrins) act as molecular "Velcro" that cells use to anchor themselves to molecules in extracellular space & to each other CAMs
sticky glycoproteins (cadherins, integrins) act as "arms" that __ cells use to haul themselves past one another migrating
sticky glycoproteins (cadherins, integrins) act as SOS signals, sticking out from blood vessel lining that rally __ __ to nearby infected or injured area protective WBCs
sticky glycoproteins (cadherins, integrins) act as __ __ that respond to local tension at cell surface by stimulating synthesis or degradation of adhesive membrane junctions mechanical sensors
sticky glycoproteins (cadherins, integrins) act as __ of intracellular signals that direct cell migration, proliferation, & specialization transmitters
large, diverse group of integral proteins & glycoproteins that serve as binding sites for signaling molecules membrane receptors definition
actual coming together & touching of cells, & is means by which cells recognize one another contact signaling
contact signaling is particularly important for normal __ & __ development; immunity
some bacteria & other infectious agents use contact signaling to identify their "preferred" __ tissues/organs target
most plasma membranes receptors are involved in __ signaling chemical
different cells respond in different ways to the __ ligand same
ligand that stimulates skeletal muscle cells to contract, but inhibits heart muscle acetylcholine
target cell's response to chemical signaling depends on __ __ that receptor is linked to, not specific ligand that binds to it internal machinery
when ligand binds to membrane receptor, receptor's __ changed, & cell proteins are __ in some way structure; altered
example of ligand changing membrane receptor's structure muscle proteins change to __ __ generate force
some membrane receptor proteins are __ proteins that function as enzymes catalytic
common in muscle/nerve cells; respond to ligands by transiently opening/closing ion gates, which in turn changes excitability of cell chemically gated channel-linked receptors
some lipid rafts group together many receptor-mediated elements, thus __ cell signaling facilitating
protein that relays signals btwn extracellular 1st messengers, such as hormones or neurotransmitters, & intracellular 2nd messengers, such as cyclic AMP, via an effector enzyme G protein
intracellular molecule generated by binding of chemical to plasma membrane receptor; mediates intracellular responses to chemical messenger 2nd messengers
intracellular 2nd messenger that mediates effects of 1st (extracellular) messenger (hormone or neurotransmitter); formed from ATP, by plasma membrane enzyme (adenylate cyclase) cyclic AMP
2 important 2nd messengers; both typically activate protein kinase enzymes, which transfer phosphate groups from ATP to other proteins cyclic AMP & ionic calcium
when protein kinase is activated by 2nd messenger, it can activate a(n) __ __ of enzymes that bring about desired cellular activity; because single enzyme can catalyze hundred of reactions, this __ __ of such a chain of events is tremendous whole series; amplification effect
key signaling pathway involved in neurotransmission, smell, vision, & hormone action G protein signaling system
one of simplest molecules; 1nitrogen & 1oxygen; environmental pollutant & 1st gas known to act as biological messenger; slips in/out of cells easily; unpaired electrons make highly reactive NO
certain plasma membrane proteins are channel proteins that respond to changes in membrane potential by opening or closing channel electrical signaling
cytoplasm is site where most cellular activities are __ accomplished
cytosol is complex mixture with properties of both a(n) __ & a(n) __ __ colloid; true solution
cytoplasmic organelles are __ __ of cell metabolic machinery
chemical substances that may/may not be present, depending on cell type inclusions
stored nutrients, suck as glycogen granules abundant in liver/muscle cells; lipid droplets common in fat cells; melanin granules seen in certain cells of skin/hair; water-containing vacuoles; & crystals of various types are all examples of inclusions
membrane enabling membranous organelles to maintain internal environment different from that of surrounding cytosol, called __, is crucial to cell functioning compartmentalization
without compartmentalization, thousands of enzymes would be randomly __ & biochemical __ would be chaotic mixed; activity
organelle's membrane often unites it w/rest of interactive intracellular system called __ system endomembrane
organelle membrane's lipid makeup allows it to __ & __ w/other organelles recognize; interact
glycolipid plasma-membrane lipid possessing a sugar chain that functions in cell recognition
phospholipid most abundant molecule found within lipid bilayer of plasma membrane
cholesterol plasma-membrane lipid that improves rigidity of plasma membrane & increases membrane's impermeability to water
protein component of plasma membrane that can act as doorway for charged particles
endocytosis method by which large particles & macromolecules enter cell by infolding of plasma membrane
osmosis movement of water across a selectively permeable plasma membrane from region of high concentration to region of low concentration
exocytosis mechanism by which substances are moved from cell cytoplasm to outside of cell by fusion of a vesicle w/plasma membrane
diffusion tendency of molecules to move along their concentration gradient from region of high-low concentration
transport mechanisms methods carry molecules, pump molecules, or form channels through which specific molecules pass across plasma membrane
phagocytosis endocytosis of large items, such as bacteria or cellular debris
pinocytosis endocytosis of a tiny quantity of extracellular fluid containing solute molecules
receptor-mediated endocytosis endocytosis that utilizes selective plasma membrane receptor proteins
hormones such as insulin, low-density lipoproteins move into cell by receptor-mediated endocytosis
water movement across membrane into cell by osmosis
movement of oxygen, carbon dioxide, and other small uncharged molecules across membrane into cell diffusion
movement of large particles, bacteria, or cellular debris by endocytotic vesicle into cell phagocytosis
molecules moving against the concentration gradient into cell by active transport mechanisms
mitochondrion characteristics cristae; matrix
ribosome characteristics composed of two subunits; can be "free" in the cytosol or attached to rough ER
rough ER characteristics produces protein transport vesicles
Golgi apparatus characteristics possesses a cis and trans side; composed of cisternae
centrioles characteristics composed of microtubules arranged in nine groups of three
microfilaments characteristics thinnest members of the cytoskeleton are composed of strands of actin protein
intermediate filaments characteristics cytoskeleton members are tough, insoluble protein fibers that possess a high tensile strength
microtubules characteristics hollow tubular members of cytoskeleton composed of spherical protein subunits & can be quickly assembled & disassembled by cell
chromatin strands of DNA and associated histones in the nucleus of a non-dividing cell
nuclear envelope, or nuclear membrane membrane that surrounds the nucleus of a cell
nuclear pore tiny passageway that allows large molecules to freely pass in and out of the nucleus
nucleolus dark-staining body found in the nucleus of a cell that functions in producing ribosomes
nucleoplasm jelly-like fluid found within the nucleus of a cell
chromosomes dark-staining, rod-shaped structures composed of highly coiled chromatin, found in cells undergoing cell division
histones spherical protein molecules around which DNA wraps
extended chromatin fine, uncoiled strands of DNA in the nucleus of a non-dividing cell
condensed chromatin dark-staining regions in the nucleus of a non-dividing cell composed of tightly coiled strands of DNA
nucleosome section of DNA and its eight associated histone proteins
G1 cell is metabolically active, synthesizing proteins, and growing rapidly
G2 cell division enzymes are synthesized, and the centrioles complete replication
S DNA replicates itself
metaphase chromosomes line up along cell equator
prophase chromatin condenses into chromosomes; centrioles move toward opposite poles of the cell
anaphase identical sets of chromosomes moved to opposite sides of cell
telophase chromosomes uncoil and revert to chromatin; nuclear membranes form around the sets of chromosomes
protein synthesis is function of ribosomes
lipid synthesis is function of smooth ER
intracellular digestion is function of lysosomes
organize spindle during mitosis centrioles
support cell & give it shape; involved in cell movements microtubules
product produced by mitochondrion ATP
product produced by rough ER transport vesicles
product produced by Golgi apparatus lysosomes & secretory vesicles
product produced by nucleolus ribosomes
product produced by centrioles cilia & flagella (microtubules)
events occurring in cytokinesis division of the parent cell cytoplasm into two daughter cells
events occurring in mitosis separation of two identical sets of chromosomes to opposite sides of the parent cell
events occurring in interphase non-dividing stage involving rapid growth, DNA replication, and preparation for division
random motion of a substance resulting in movement from area of high to lower concentration characteristics of diffusion
passive process utilizing a protein carrier or channel characteristics of facilitated diffusion
movement of a substance that utilizes a carrier; energy comes directly from hydrolysis of ATP characteristics of primary active transport
movement of a substance that utilizes a carrier, and has a concentration gradient as the source of energy characteristics of secondary active transport
carries genetic instructions from nucleus to the site of protein synthesis function of mRNA
uses an anticodon to guide its attached amino acid to the complementary codon on the mRNA at the ribosome function of tRNA
combines in a complex with proteins to make the large and small subunits of a ribosome function of rRNA
can control, or inhibit, certain genes function of microRNA
adjacent cells joined by a line of membrane proteins that form an impermeable junction tight junction
button-like junctions that use linker proteins to hold adjacent cells together desmosomes
adjacent cells held together by connexon proteins that form cylinders allowing ion flow between the cells' cytoplasm gap junctions
tiny finger-like projections of the plasma membrane; increase surface area for absorption microvilli
motile cellular extensions found in large numbers in some epithelial cells cilia
long, cellular projections that are tail-like and aid in propulsion flagella
cytoskeleton is an elaborate network of rods running throughout the cytosol, functioning in supporting cellular structures & generating cell movements
DNA nucleic-acid molecules are involved in transcription but not translation in the synthesis of a particular polypeptide
DNA is copied into mRNA in transcription within the nucleus in the synthesis of a(n) particular polypeptide
mRNA start codon, AUG, matches up with a tRNA anticodon GAC
definite changes in the __ of the cell membrane can be seen in a cell that is becoming cancerous glycocalyx
simple diffusion is best described as substances moving down a concentration gradient passively
crenation takes place when a cell is placed in a(n) hypertonic solution
type of RNA contains regions that act as a switch to turn protein synthesis on & off for the protein it codes for Riboswitches
Created by: lfrancois



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