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A & P I Ch 3

Cells: The Living Units

QuestionAnswer
Cell Theory cell is the smallest structural & functional living unit..organismal functions depend on individual & collective cell functions..biochemical activities of cells are dictated by their specific subcellular structures..continuity of life has a cellular basis
The cell is the _____ & _____ smallest structure & functional living unit
Organismal functions depend on _____ & _____ individual & collective cell functions
Biochemical activities of cells are _____ dictated by their specific subcellular structures
Developmental aspects of cells all cells of the body contain same DNA but aren't identical..chem signals in the embryo channel cells into specific developmental pathways by turning some genes off..elimination of excess, injures, or aged cells occurs through programmed rapid cell death
All cell of the body contain _____ the same DNA but are not identical
Chemical signals in the embryo channel _____ cells into specific developmental pathways by turning some genes off
Development of _____ & _____ features in cells is called _____ specific...distinctive...cell differentation
Call Differentiation development of specific & distinctive features in cells
Apoptosis programmed rapid cell death
Hypertrophy enlargement of skeletal muscles
Theories of Cell Aging wear & tear theory...immune system disorders...genetic theory
Wear & Tear Theory little chemical insults & free radicals have cumulative effects
Immune System Disorders autoimmune responses & progressive weakening of the immune response
Genetic Theory cessation of mitosis & cell aging are programmed into genes...telomeres may determine the # of times a cell can divide
Telomeres strings of mucleotides on the ends of chromosomes
Generalized Cell all cells have common structures...human cells have 3 basic parts
3 basic parts of human cells plasma membrane...cytoplasm...mucleus
Cytoplasm intracellular fluid containing organelles...water constitutes 60-80%
Nucleus bound by bi layer membrane...distinctly seperated inside of cytoplasm
Mitochondrion takes glucose & oxygen & makes ATP
Plasma Membrane universal structure..bimolecular layer of lipids/proteins in a constantly changing fluid mosaic..plays dynamic role in cellular activity..seperates intracellular fluid from extracellular fluid..vital to transport of nutrients & waste products in/out cell
Phospholipid Bilayer bimolecular layer of lipids & proteins
Tnterstitial Fluid = ECF that surrounds cells
Extracellular Materials body fluids...cellular secretions...extracellular matrix
Body Fluids interstitial fluid...blood plasma...cerebrospinal fluid
Cellular Secretions intestinal& gastric fluids...saliva...mucus...serous fluid
Extracellular Matrix abundunt jellylike mesh containing proteins ^& polysaccharides in contact with cells
Membrane Lipids 75% phospholipids (lipid bilayer)...5% glycolipids...20% cholesterol
75% phospholipids phosphate heads: polar & hydrophilic...fatty acid tails: nonpolar & hydrophobic
polar = dipole pos & neg charge
Hydrophillic water loving...water soluble
Hydrophobic fear water...water insoulble
Hydrophillic = libophobic...will not dissolve in lipids
Hydrophobic = libophilic...will dissolve in lipids
5% glycolipids lipids with polar sugar groups on outer membrane surface that helps stabilize the membrane
20% cholesterol increases membrane stability & fluidity
Functions of Membrane Proteins Transport...Receptors for signal transduction...attachment to cytoskeleton & extarcellular matrix...emzymatic activity...intracellular joining...cell-cell recognition
Transport Function of Membrane Proteins protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute
Receptors for Signal Tranduction membrane protein exposes to the outside of the cell may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone
Attachment to the Cytoskeleton & Extracellular Matrix elements of the cytoskeleton & the extracellular matrix may be anchored to the membrane proteins, which help maintain cell shape & fix the location of certain proteins
Cytoskeleton cell's internal supports
Extracellular Matrix fibers & other substances outside the cell
Plasma Membrane Flexible outer boundary
Cyotplasm intracellular fluid containing organelles
Nucleus control center...bound by bi-layer membrane...distinctly seperated inside of cytoplasm
Osmosis movement of solvent (water)...across a selectively permeable membrane
Membrane Transport plasma membranes are selectively permeable...some molecules easily pass through the membrane; others do not
Types of Membrane Transport passive processes...active processes
Passive Processes No cellular energy (ATP) required...substance moves down its concentration gradient
Active Processes Energy (ATP) required...occurs only in living cell membranes
What determines whether or not a substance can passively permeate a membrane? lipid solubility of substance (because membrane is a phospholipid bilayer)...channels of appropriate size (proteins provide a channel for movement)...carrier proteins
Types of passive processes simple diffusion...carrier-mediated facilitated diffusion...channel-mediated facilitated diffusion...osmosis
Simple Diffusion Lipophilic (Nonpolar lipid-soluble)(hydorphobic) substances diffuse...directly through the phospholipid bilayer
Facilitated Diffusion certain lipophobic (hydrophilic) (water soluble) molecules use carrier proteins or channel proteins
Carrier proteins & channel proteins both _____ exhibit specificity (selectivity)...are saturable (rate is determined by # of carriers or channels)...can be regulated in terms of activity & quantity
Facilitated Diffusion using Carrier Proteins Transmembrane integral proteins transport specific polar molecules (e.g. sugars & amino acids)...binding of substrate cause shape change in carrier...Is a passive process so no energy (ATP) required
Facilitated Diffusion using Channel Proteins Is a passive process so no energy (ATP) required...aqueous channels formed by transmembrane proteins selectively transport ions or water
2 Types of Facilitated Diffusion using Channel Proteins Leakage Channels...Gated Channels
Leakage Channels are _____ always open
Gated Channels are _____ controlled by chemical (smell, taste) or electrical or mechanical (hearing) signals...No energy required
Osmosis No energy req..movement of solvent (H2O) across a selectively permeable membrane..H2O conc. is determined by solute concentration..osmolarity..when solutions of different osmolarity are seperated by a membrane, osmosis occurs until equilibrium is reached
Water concentration is determined by _____ Solute Concentration
Water concentration is determined by solute concentration because _____ Solute particles displace water molecules
Osmolarity the measure of total concentration of solute particles
Importance of Osmosis When osmosis occurs, water enters or leaves a cell...change in cell volume disrupts cell function
Tonicity the ability of a solution to cause a cell to shrink or swell
Isotonic A solution with the same solute concentration as that of the cytosol...cells retain their normal size & shape...same solute/water concentration as inside cells...water moves in & out
Hypertonic solution having greater solute concentration than that of the cytosol...cell shrink because H2O leaves cell...cells lose H2O by osmosis & shrink
Hypotonic a solution having lesser solute concentration than that of the cytosol...cells take on water by osmosis until they become bloated & burst
Differences b/w Active & Passive Processes Active processes require expenditure of energy...ALL active processes require a carrier protein...Gradient independent (can move either way (usually uphill))
2 types of Active Processes Active Transport...Vesicular Transport
Active Transport requires energy...requires carrier proteins...moves solutes against a concentration gradient...moves solutes from low to high concentration...2 types
2 Types of Active Transport Primary active transport...Secondary active transport
Primary Active Transport Energy from hydrolysis of ATP causes shape change in transport protein so that bound solutes (ions) are "pumped" across the membrane
Primary Active Transport ~ Sodium-Potassium Pump located in all plasma membranes...involved in primary & secondary active transport of nutrients & ions...maintains electrochemical gradients essential for functions of muscle & nerve tissues...moves sodium out & potassium in...requires Hydrolysis of ATP
Secondary Active Transport depends on an ion gradient created by primary active transport...energy stored in ionic gradients is used indirectly to drive transport of other solutes
Secondary Active Transport ~ Cotransport always transports more than one substance at a time...2 types
2 Types of Cotransport Symport System...Antiport System
Symport System 2 substances transported in some direction
Antiport System 2 Substances transported in opposite directions
Vesicular Transport transport of large particles, macromolecules, & fluids across plasma membrane...requires cellular energy...vesicules that transport the materials, is made up of a phospholipid bilayer
Vesicular Transport Functions Exocytosis...Endocytosis...Transcytosis...Substance (vesicular Trafficking
Exocytosis transport out of the cell
Endocytosis transport into the cell
Transcytosis transport into, across, & then out of the cell
Substance (vesicular) Trafficking transport from one area or organelle in the cell to another
Endocytosis & Transcytosis involve formation of protein-coated vesicles...often receptor mediated therefore very selective
Type of Endocytosis phagocytosis...pinocytosis...receptor-mediated
Phagocytosis Solid phase endocytosis...cell engulfs a large particle (solid) by forming projecting pseudopods ("false feet") around it & enclosing it w/ a membrane sac called a phagosome...phagosome is combined w/ a lysosome
After phagocytosis undigested contents remain in the vesicle (now called a residual body) or are ejected by expcytosis
2 Examples of Phagocytosis Macrophages...some white blood cells
Lysosome digesting body
Phagosome eating body
Pinocytosis Fluid-phase endocytosis...plasma membrane infolds "gulps" bringing extracellular fluid & solutes into tiny vesicles inside of the cell...no receptors are used, so the process is nonspecific
Example of Pinocytosis nutrient absorption in the small intestine
Receptor-Mediated Enducytosis receptors provide main route for endocytosis & transcytosis...Extracellular substances bind to the specific receptor proteins, enabling the cell to ingest & concentrate specific substances
Ligands the specific substances that are being taken in by Receptor-Mediated endocytosis
Receptor-Mediated Endocytosis examples uptake of enzymes, low-density lipoproteins, iron, & insulin
Exocytosis exampples hormone secretion...neurotransmitter release...mucus secretion...ejection of wastes
Membrane Potential seperation of oppositely charged particles (ions) across a membrane creates a membrane potential (potential energy measured as voltage)...resting membrane potential (RMP)...electrical & chemical
RMP Resting membrane potential...voltage measured in resting state in all cells...ranges from -50 to -100 mV inside different cells...results from diffusion & active transports of ions (mainly K+)
Generation & Maintenance of RMP Na+~K+ pump continuously ejects Na+ from cell & carries K+ back in..some K+ continually diffuses down its conc. gradient out of the cell through K+ leakage channels..membrane interior becomes neg. (relative to exterior) b/c of large anions trapped in cell
Generation & Maintenance of RMP ~~~~~CONTINUED~~~~~ Electrochemical gradient begins to attract K+ back into cell...RMP is est. @ the point where the electrical gradient balances the K+ concentration gradient...A steady state is maintained
Cell-Enviroment Interactions Involves glycoproteins & proteins of glycocalyx
Roles of Cell Adhesion Molecules anchor cells to extracellular matrix or to each other...assist in movement of cells past one another...CAMS of blood vessel lining attract white blood cells to injured or infected areas...stimulate synthesis or degradation of adhesive membrane junctions
Roles of Cell Adhesion Molecules ~~~~~CONTINUED~~~~~ Transmit intracellular signals to direct cell migration, proliferation, & specialization
Cytoplasm located b/w plasma membrane & nucleus...contains cytosol, cytoplasmic organelles, & inclusions
Cytosol composed of 80% of H2O along with solutes (protein, salts, sugars, etc.)
Cytoplasmic Organelles metabolic machinery of cell...all organelles in the cell are enveloped in a phospholipid bilayer membrane which helps compartmentalize work in the cell & lends to specialized function & increases surface area which organizes the metabolism of the cell
Inclusions granules of glycogen or pigments, ;ipid droplets, vacuoles, & crystals
Endosymbiotic into...sharing space or life with each other
2 Types of Cytoplasmic Organelles membranous...nonmembranous
Membranous Cytoplasmic Organelles mitochondria, peroxisomes, lysomes, endoplasmic reticulum, golgi apparatus
Nonmembranous Cytoplasmic Organelles cytoskeleton, ribosomes
Mitochondria double-membrane structure (phospholipid bilayer) w/ shelflike cristae...provides most of the cell's ATP via aerobic cellular respiration...contain their own DNA 7 RNA...able to replicate
Ribosomes granules containing protein & rRNA...site of protein synthesis...free ribosomes synthesize soluble proteins...membrane-bound ribosomes (on rough ER) synthesize proteins to be incorporated into membranes or exported from the cell
Endoplasmic Reticulum (ER) endoplasmic = inside cytoplasm...interconnected tubes & parallel membranes enclosing cisternae...continuous w/ nuclear membrane...2 varieties
Cisternae great big sacs that hold a variety of things (mainly proteins)
2 varieties of ER Rough ER & Smooth ER...both play a significant role in the Endomembrane System (all structures in the cell that are tubelike & contain cisternae)
Rough ER external surface studded w/ ribosomes...manufactures all secreted proteins...synthesizes membrane integral proteins & phospholipids
Smooth ER tubules arranged in a looping network...enzyme (integral protein) functions
Enzyme functions of smooth ER in Liver, with hormones, & in Intestinal cells in the liver - lipids & cholesterol metabolism, breakdown of glycogen, & along w/ the kidneys, detox of drugs, pesticides, & carcinogens...synthesis of steroid-based hormone...in intestinal cells - absorption, synthesis, & transport of fats
Enzyme functions of smooth ER in skeletal & cardiac muscle called Sarcoplasmic Reticulum...storage & release of calcium (required for muscle to contract)
Golgi Apparatus stacked & flattened membranous sacs...warehouse of the cell...proteins, fats, lipids, etc ar packaged in trafficking vessicles & move to Golgi, then remodified, repackaged & transported to secretory vesicles
What organelles do lysosomes originate from? Golgi Apparatus
Phagolysosome formed by the combining of lysosome & phagosome...vital to the digestion of ingested materials in the cell (toxins, viruses, bacteria, etc.)
Lysosomes Spherical membranous bags containing digestive enzymes (acid hydrolases)...digest ingested bacteria, viruses, & toxins...degrade nonfunctional organelles...breakdown & release glycogen (imp in body that needs additional energy)
Lysosomes (Continued) breakdown bone to release Ca2+...dstroy cells in injured or nonuseful tissue (autolysis)
Endomembrane System overall function produce, store, & export biological molecules...degrade potentially harmful substances
Peroxisomes membranous sacs containing powerful oxidases & catalases (take Hydrogen Peroxide (2H2O2) & turns it into O & H2O)...detoxify harmful or toxic substances...neutralize dangerous free radicals (highly reactive chemicals w/ unpaired electrons)
Cytoskeleton water insoluble fibrous proteins...an elaborate series of rods throughout cytosol (microtubules, microfilaments, intermediate filaments)
Microfilaments Dynamic actin strands attached to cytoplasmic side of plasma membrane...involved in cell motility, change in shape, endocytosis, & exocytosis
Intermediate Filaments tough, insoluble ropelike protein fibers...resist pulling forces on the cell & attach to cell junctions of other cells...H2O insoluble
Microtubules Tubulin (spherical protein subunits) create dynamic hollow tubes that contract...determine overall shape of cell & distribution of organelles
Motor Molecules protein complexes that function in motility (e.g. movement of organelles & contraction)...powered by ATP
Cellular Extensions Cilia & Flagella...microvilli
Cilia & Flagella whiplike, motile extensions on surfaces of certain cells...contain microtubules & motor molecules...Cilia move substances across cell surfaces...longer flagella propel whole cells (tail of sperm)
Microvilli fingerlike extensions of plasma membrane...increase surface area for absorption...core of actin filaments for stiffening
Nucleus genetic library w/ blueprints for c-ular proteins..responds to signals & dictates kinds & amts of proteins to be synthesized..most c's are uninucleate, red blood c's are anucleate..skeltal musc c's, bone destruction c's, & some liver c's are multinucleate
Nucleolus function is synthesis of ribosomes
Nuclear Envelope double-membrane barrier containing pores...outer layer is continuous with RER & bears ribosomes...inner lining (nuclear lamina) maintains shape of nucleus...pore complex regulates transport of large molecules into & out of mucleus
Nucleoli involved in rRNA synthesis & ribosome subunit assembly
Chromatin condensed chromosomes...threadlike strands of DNA, histone proteins (bases to stabilize DNA & RNA) & RNA...arranged in fundamental units called nucleosomes...condense into barlike bodies called chromosomes when the cell starts to divide
Created by: retazba