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Ch. 3
A&P The Cellular Level of Organization
| Question | Answer |
|---|---|
| living structural and functional units enclosed by a membrane | cells |
| all cells arise from existing cells by the process of __ __, in which one cell divides into 2 identical cells | cell division |
| __ or __ is the study of cellular structure and function | cell biology cytology |
| 3 main parts of cells | plasma membrane cytoplasm nucleus |
| __ forms the cell's flexible outer surface, separating the cell's internal and external environment; it is a selective barrier that regulates the flow of materials in and out of the cell | plasma membrane |
| plays a key role in communication among cells and btwn cells and their external environment | plasma membrane |
| __ consists of all cellular contents btwn the plasma membrane and the nucleus | cytoplasm |
| what are the 2 components of the cytoplasm | cytosol organelles |
| __, the fluid portion of cytoplasm, contains water, dissolved solutes, and suspended particles | cytosol |
| within the cytosol are several different types of __; each of theses has a characteristic shape and specific functions | organelles |
| some ex of organelles (7) | cytoskeleton ribosome endoplasmic reticulum golgi complex lysosomes peroxisomes mitochondria |
| __ is a large organelle that houses most of a cell's DNA | nucleus |
| within the nucleus, each __ a single molecule of DNA associated with several proteins, contains thousands of hereditary units called __ that control most aspects of cellular structure and function | chromosomes genes |
| the __ __, a flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell | plasma membrane |
| the plasma membrane is best described by using a structural model called __ __ __ | fluid mosaic model |
| the __ __ allow passage of several types of lipidsoluble molecules but act act as a barrier to entry or exit of charged or polar substances | membrane lipids |
| the __ is the basic living, structural and functional unit of the body | cell |
| __ are fluid structures bc the lipids and many of the proteins are free to rotate and move sideways in their own half of the bilayer | membranes |
| the basic structural framework of the plasma membrane is the __ __, two back-to-back layers made up of three types of lipid molecules | lipid bilayer |
| what are the 3 lipids that make up the lipid bilayer | phospholipids cholesterol glycolipids |
| about 75% of the membrane lipids are __, lipids that contain phosphorus | phospholipids |
| present in smaller amounts, are __ (about 20%), a steroid with an attached -OH (hydroxyl) group, and various __ (about 5%), lipids with attached carbohydrate groups | cholesterol glycolipids |
| the bilayer arrangement occurs bc the lipids are __ molecules, which means that they have both polar and nonpolar parts | amphipathic |
| in phospholipids, the polar part is the phosphate-containing head which is __; the nonpolar parts are the two long fatty acid tails which are __ | hydrophilic hydrophobic |
| membrane proteins are classified as __ or __ according to whether they are firmly embedded in the membrane | integral peripheral |
| __ __ extend into or through the lipid bilayer among the fatty acid tails and are firmly embedded in it | integral proteins |
| most integral proteins are __ __ which means that they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid | transmembrane proteins |
| integral proteins are __, have polar and nonpolar parts | amphipathic |
| integral proteins __ regions protrude into either the watery extracellular fluid or the cytosol, and their __ regions extend among the fatty acid tails | hydrophilic hydrophobic |
| __ __ are not as firmly embedded in the membrane; they are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane | peripheral proteins |
| many integral proteins are __ proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid | glycoproteins |
| the carbohydrates of glycoproteins are __, chains of 2 to 60 monosaccharides that may be straight or branched | oligosaccharides |
| the carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat called the __ | gylcocalyx |
| the __ enables cells to adhere to one another in some tissues and protects cells from being digested by enzymes in the extracellular fluid | glycocalyx |
| some integral proteins form __ __, pores or holes that specific ions can flow through to get into or out of the cell | ion channels |
| most ion channels are __; they allow only a single type of ion to pass through | selective |
| other integral proteins act as __, selectively moving a polar substance or ion from one side of the membrane to the other | carriers |
| carriers are also known as __ | transporters |
| integral proteins called __ serve as cellular recognition sites; each type of this recognizes and binds a specific type of molecule | receptors |
| a specific molecule that binds to a receptor is called a __ of the receptor | ligand |
| some integral proteins are __ that catalyze specific chemical reactions inside or outside surface of the cell | enzymes |
| integral proteins may also serve as __ that anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside or outside the cell | linkers |
| __ proteins also serve as enzymes and linkers | peripheral |
| membrane glycoproteins and glycolipids ofter serve as __ __; they may enable a cell to (1) recognize other cells of the same kind during tissue formations or (2) recognize and respond to potentially dangerous foreign cells | cellidentity markers |
| __ proteins help support the plasma membrane, anchor integral proteins, and participate in mechanical activities such as moving materials and organelles within cells, changing cell shape in dividing and muscle cells, and attaching cells to one another | periperal |
| each double bond puts a __ in the fatty acid tail, which increases membrane fluidity by preventing lipid molecules from packing tightly in the membrane | kink |
| __ makes the lipid bilayer stronger but less fluid at normal body temp | cholesterol (at low temp, cholesterol has the opposite effect - it increases membrane fluidity) |
| the term __ means that a structure permits the passage of substances through it; while __ means that a structure does not permit the passage of substances through it | permeable impermeable |
| plasma membranes permit some substance to pass more readily than other. This property of membranes is termed __ __ | selective permeability |
| the lipid bilayer portion of the membrane is permeable to __, __ molecules but is impermeable to __ and __, __ __ molecules | nonpolar, charged ions and large, uncharged polar |
| the lipid bilayer is slightly permeable to small, uncharged polar molecules like __ and __ | water urea (a waste product from the breakdown of amino acids) |
| __ proteins that act as channels and carriers increase the plasma membrane's permeability to a variety of ions and uncharged polar molecules that cannot cress the lipid bilayer unassisted | transmembrane |
| the __ __ of the plasma membrane allows a living cell to maintain different concentrations of certain substances on either side of the plasma membrane | selective permeability |
| a __ __ is a difference in the concentration of a chemical from one place to another, such a from the inside to the outside of the plasma membrane | concentration gradient |
| typically the inner surface of the plasma membrane is more __ charged and the outer surface is more __ charged | negatively positively |
| A difference in electrical charges btwn two regions constitutes an __ __. Bc it occurs across the plasma membrane, this charge difference is termed the __ __. | electrical gradient membrane potential |
| the combined influence of the concentration gradient and the electrical gradient on movement of a particular ion is referred to as its __ __ | electrochemical gradient |
| substances generally move across cellular membranes via transport processes that can be classified as __ or __ , depending on whether they require cellular energy | passive active |
| in __ __, a substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy; kinetic energy is intrinsic to the particles that are moving; there is no input of energy from the cell | passive process |
| in __ __, cellular energy is used to drive the substance uphill against its concentration or electrical gradient | active processes |
| what type of cellular energy is usually use to drive an active process? | adenosine triphosphate (ATP) |
| an example of active process is __ __ | active transport |
| another way that some substances may enter and leave cells is an active process in which tiny, spherical membrane sacs referred to as __ are used | vesicles |
| __ is when vesicles detach from the plasma membrane while bringing materials into a cell and __ are the merging of vesicles with the plasma membrane to release materials from the cell | endocytosis exocytosis |
| __ is a passive process in which the random mixing of particles in a solution occurs bc of the particles' kinetic energy | diffusion |
| both __, the dissolved substances, and the __, the liquid that does the dissolving undergo diffusion | solutes solvent |
| what are 3 types of diffusion? | simple diffusion facilitated diffusion osmosis |
| __ __ is a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins | simple diffusion |
| __, __ molecules move across the lipid bilayer through the process of simple diffusion | nonpolar hydrophobic |
| examples of nonpolar, hydrophobic molecules that use simple diffusion are? (9) | oxygen, carbon dioxide, nitrogen gases fatty acids steroids fat-soluble vitamin (A,D,E and K) |
| small, uncharged polar molecules such as __, __ and small __ also pass through the lipid bilayer by simple diffusion | water urea alcohol |
| solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the plasma membrane by a passive process called __ __; this is when an internal membrane protein assists a specific substance across the membrane | facilitated diffusion |
| in __-__ __ __, a solute moves down its concentration gradient across the lipid bilayer through a membrane channel | channel-mediated facilitated diffusion |
| in facilitated diffusion, the integral membrane protein can be either a membrane __ or __ | channel or carrier |
| most membrane channels are __ channels, integral transmembrane proteins that allow passage of small, inorganic ions that are too hydrophilic to penetrate the nonpolar interior of the lipid bilayer | ion |
| the most numerous ion channels are selective for __ or __; fewer channels are available for __ or __ | K^+ or Cl^- Na^+ or Ca^2+ |
| a channel is said to be __ when part of the channel protein acts as a plug or gate, changing shape in one way to open the pore and in another way to close it | gated |
| In __-__ __ __, a carrier (also called a transporter) moves a solute down its concentration gradient across the plasma membrane; since this is a passive process, no cellular energy is required | carrier-mediated facilitated diffusion |
| the number of carriers available in a plasma membrane places an upper limit, called __ __, on the rate at which facilitated diffusion occurs | transport maximum |
| substances that move across the plasma membrane by carrier-mediated facilitated diffusion include __, __, __, and __ | glucose fructose galactose some vitamins |
| an inability to produce or utilize insulin is called __ __ | diabetes mellitus |
| what is the hormone that is related to glucose? | insulin |
| __ is a type of diffusion in which there is net movement of a solvent through a selectively permeable membrane; is a passive process | osmosis |
| the solvent is __ which moves by osmosis across plasma membrane from and area of higher __ concentration or an area of lower __ concentration | water |
| in osmosis, water moves through a selectively permeable of lower __ concentration to an area of higher __ concentration | solute |
| during osmosis, what are the two ways water molecules pass through a plasma membrane? | (1) by moving between neighboring phospholipids molecules in the lipid bilayer via simple diffusion or (2) by moving through aquaporins integral membrane proteins that function as water molecules |
| what are integral membrane proteins that function as water molecules? | aquaporins |
| in osmosis the solution with the impermeable solute exerts a force on the membrane called __ __ | osmotic pressure |
| __ is the movement of water molecules through a selectively permeable membrane | osmosis |
| a solution's __ is a measure of the solution's ability to change the volume of cells by altering their water content | tonicity |
| any solution in which a cell maintains its normal shape and volume is an __ __; bc there is no net water movement into or out of the cell | isotonic solution |
| __ __, a solution that has a lower concentration of solutes (higher concentration of water) than the cytosol inside the cell | hypotonic solution |
| the rupture of RBCs in this manner is called __, the rupture of other types of cells due to placement in a hypotonic solution is referred to simply as __ | hemolysis lysis |
| a __ __ has a higher concentration of solutes than does the cytosol inside the cell | hypertonic solution |
| shrinkage of cells is called __ | crenation |
| some polar or charged solutes that must enter or leave body cells cannot cross the plasma membrane through any form of passive transport bc they would need to move uphill, against their concentration gradient; this process is __ __ | active transport |
| active transport is considered an __ process bc energy is required for carrier proteins to move solutes across the membrane against a concentration gradient | active |
| what are 2 sources of cellular energy used for active transport? | (1) energy obtained from hydrolysis of adenosine triphosphate (ATP) is the source in primary active transport; (2) energy stored in an ionic concentration gradient is the source in secondary active transport |
| what are the two types of active transport? | primary active transport secondary active transport |
| In __ __ __, energy derived from hydrolysis of ATP changes the shape of a carrier protein, which pumps a substance across a plasma membrane against its concentration gradient | primary active transport |
| carrier proteins that mediate primary active transport are often called __ | pumps |
| a typical body cell expends about __% of ATP it generates on primary active transport | 40% |
| the most prevalent primary active transport mechanism expels sodium ions (Na^+) from cells and brings potassium ion (K^+) in. Bc of the specific ions it moves, this carrier is called the __-__ __ | sodium-potassium pump |
| bc a part of the sodium-potassium pump acts as an ATPase, an enzyme that hydrolyzes ATP, another name for this pump is __/__ __ | Na^+/K^+ ATPase |
| the sodium-potassium pumps must work nonstop to maintain a low concentration of __ and a high concentration of __ in the cytosol | Na^+ K^+ |
| sodium-potassium pumps maintain a low intracellular concentration of __ ions | sodium |
| in __ __ __, the energy stored in a Na^+ or H^+ concentrations gradient is used to drive other substance across the membrane against their own concentration gradient | secondary active transport |
| transporters move two substances in the same direction they are called __,; __ in contrast, move two substance in opposite directions across the membrane | symporters antiporters |
| a __ is a small, spherical sac; it also import materials from and release materials into extracellular fluid | vesicles |
| during __, materials move into a cell in a vesicle formed from the plasma membrane | endocytosis |
| in __, materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell | exocytosis |
| both endocytosis and exocytosis require energy supplied by ATP. Thus, transport in vesicles is an __ process | active |
| what are the three types of endocytosis? | receptor-mediated endocytosis phagocytosis bulk-phase endocytosis |
| __ is a highly selective type of endocytosis by which cells take up specific ligands; imports materials that are needed by cells | receptro-mediated endocytosis |
| __ are molecules that bind to specific receptors | ligands |
| a __ forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the extracellular fluid | vesicle |
| __ is a form of endocytosis in which cell engulfs large solid particles, such as worn-out cells, whole bacteria, or viruses | phagocytosis |
| body cells called __ are able to carry out phagocytosis | phagocytes |
| two main types of phagocytes are __, located in many body tissues, and __ a type of white blood cells | macrophages neutrophils |
| phagocytosis begins when the particle binds to a plasma membrane receptor on the phagocyte, causing it to extend __, projections of its plasma membrane and cytoplasm | pseudopods |
| pseudopods surround the particle outside the cell, and the membranes fuse to form a vesicle called a __, which enters the cytoplasm; it fuses with one or more lysosomes and __ enzymes break down the ingested material | phagosome lysosomal |
| __ is a vital defense mechanism the helps protect the body from disease | phagocytosis |
| in most cases any undigested materials in the phagosome remain indefinitely in a vesicle called a __ __; these are then either secreted by the cell via exocytosis or they remain stored in the cell as lipofuscin granules | residual body |
| through phagocytosis, __ dispose of invading microbes and billions of aged, worn-out red blood cells every day; __ also help rid the body of invading microbes | macrophages neutrophils |
| __ is a mixture of dead neutrophils, macrophages, and tissue cells and fluid in an infected wound | pus |
| most body cells carry out __-__ __, also called __, a from of endocytosis in which tiny droplets of extracellular fluid are taken up | bulk-phase endocytosis pinocytosis |
| __ releases material from a cell | exocytosis |
| all cells carry out exocytosis, but it is especially important in two types of cells: (1) __ cells that liberate digestive enzymes, hormones, mucus, or other substances and (2) __ cells that release substances called neurotransmitters | secretory nerve |
| during exocytosis, membrane-enclosed vesicles called __ __ form inside the cell, fuse with the plasma membrane, and release their contents into the extracellular fluid | secretory vesicles |
| transport in vesicles may also be used to successively move a substance into, across, and out of a cell, this is celled __; vesicles undergo endocytosis on one side of a cell, move across the cell, and then undergo exocytosis on the opposite side | transcytosis |
| __ consists of all the cellular contents btwn the plasma membrane and the nucleus | cytoplasm |
| cytoplasm has two components: (1) the __ and (2) __, tiny structures that perform different functions in the cell | cytosol organelles |
| the __ (__ __) is the fluid portion of the cytoplasm that surrounds organelles and constitutes about 55% of total cell volume | cytosol (intracellular fluid) |
| the __ is a network of protein filaments that extends throughout the cytosol | cytoskeleton |
| three types of filamentous proteins contribute to the cytoskeleton's structure, as well as the structure of other organelles; in order of their increasing diameter, these structures are __, __ __, and __ | microfilaments intermediate filaments microtubules |
| __ are he thinnest elements of the cytoskeleton; are most prevalent at the edge of a cell | microfilaments |
| microfilaments are composed of the proteins __ and __ | actin and myosin |
| what are the two general functions of microfilaments? | 1) they help generate movement 2) provide mechanical support |
| microfilaments provide much of the mechanical support that is responsible for the basic __ and __ of cells | strength shape |
| microfilaments also provide mechanical support to cell extensions called __, nonmotile, microscopic fingerlike projections of the plasma membrane | microvilli |
| __ __ are thicker than microfilaments but thinner than microtubules | intermediate filaments |
| __ are the largest of the cytoskeleton components and are long, unbranched hollow tubs composed mainly of the protein __ | microtubules tubulin |
| the assembly of microtubules begins in an organelle called the __ | centrosome |
| microtubules help determine cell __ | shape |
| microtubules function in the __ of organelles such as secretory vesicles, of chromosomes during cell division, and of specialized cell projections, such as cilia and flagella | movement |
| what are the 2 functions of the cytoskeleton? | (1) serves as a scaffold that helps to determine a cell's shape and to organize the cellular contents; (2) aids movement of organelles within the cell, of chromosomes during cell division, and of whole cells such as phagocytes |
| __ are specialized structures within the cell that have characteristic shapes, and they perform specific functions in cellular growth, maintenance, and reproduction | organelles |
| the __ located near the nucleus, consist of two components | centrosome |
| what are the two components of the centrosome? | a pair of centrioles pericentriolar material |
| what component of the centrosome are cylindrical structures, each composed of nine clusters or three microtubules (triplets) arranged in a circular pattern | centrioles |
| surrounding the centrioles is __ which contains hundreds of ring-shaped complexes composed of the protein tubulin | pericentriolar material |
| what are the 2 functions of centrosomes? | (1) the pericentriolar material of the centrosome contains tubulins that build microtubules in nondividing cells (2) the pericentriolar material of the centrosome forms the mitotic spindle during cell division |
| __ are the dominate components of cilia and flagella, which are motile projections of the cell surface | microtubles |
| __ are numerous, short, hairlike projections that extend from the surface of the cell | cilia |
| each cilium is anchored to a __ __ just below the surface of the plasma membrane; it is similar in structure to a centriole and functions in initiating the assembly of cilia and flagella | basal body |
| in __ __, the extremely thick mucous secretions that are produced interfere with ciliary action and the normal functions of the respiratory tract | cystic fibrosis |
| __ are similar in structure to cilia but are typically much longer; usually they move an entire cell | flagella |
| functions of cilia and flagella (1 each) | 1) cilia move fluids along a cell's surface 2) a flagellum moves an entire cell |
| __ are the sites of protein synthesis | ribosomes |
| the name of these tiny structures, ribosomes, reflects their high content of one type of ribonucleic acid, __ __, but each one also includes more than to proteins | ribosomal RNA (rRNA) |
| what are the functions of the ribosomes? (2) | (1) ribosomes associated with endoplasmic reticulum synthesize proteins destined for insertion in the plasma membrane or secretion from the cell; (2) free ribosomes synthesize proteins used in the cytosol |
| the __ __ or __ is a network of membranes in the form of flattened sacs or tubules; extends from the nuclear envelop(membrane around the nucleus) to which it is connected, throughout the cytoplasm | endoplasmic reticulum |
| what are the two distinct forms of ER, which differ in structure and functions? | rough ER smooth ER |
| __ __ is continuous with the nuclear membrane and usually is folded into a series of flattened sacs | rough ER |
| the outer surface of rough ER is studded with __, the sites of protein synthesis | ribosomes |
| __ __ extends from the rough ER to form a network of membrane tubules; does not have ribosomes on the outer surfaces of its membrane and bc of this does not synthesize proteins but it does synthesize fatty acids and steroids(ex: estrogen & testosterone) | smooth ER |
| what is the function of rough ER? | rough ER synthesizes glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane, or secreted during exocytosis |
| what is the function of smooth ER? | smooth ER synthesizes fatty acids and steroids; inactivates or detoxifies drugs and other potentially harmful substances (alcohol); removes the phosphate group from glucose-6-phosohpate; & stores & releases calcium for muscle contraction |
Created by:
jconsalo