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Flashcards

Chapter 3 Anatomy and Physiology

Johanna Keifert Science 2 English 200 cards

Cards in this deck (200)

  1. 1plasma membrane aka cell membraneforms the outer boundary of the cell, through which the cell interacts with its external environment
  2. 2plasma membrane structurelipid bilayer composed of phospholipids and cholesterol; proteins extend across or are embedded in either surface of the lipid bilayer
  3. 3plasma membrane functionfunctions as the outer boundary of cells; controls the entry and exit of substances; receptor proteins function in intercellular communication; marker molecules enable cells to recognize one another
  4. 4nucleus functioncontrol center of the cell; DNA within the nucleus regulates protein synthesis and therefore the chemical reactions of the cell
  5. 5nucleus structureenclosed by nuclear envelope, a double membrane with nuclear pores; contains chromatin (dispersed, thin strands of DNA and associated proteins), which condenses to become visible mitotic chromosomes during cell division; also contains one or more nucleoli, dense bodies consisting of ribosomal RNA and proteins.
  6. 6ribosome structureribosomal RNA and proteins form large and small subunits; some are attached to endoplasmic reticulum, whereas others (free ribosomes) are distributed throughout the cytoplasm
  7. 7ribosome functionserves as site of protein synthesis
  8. 8rough endoplasmic reticulum structuremembranous tubules and flattened sacs with attached ribosomes
  9. 9rough endoplasmic reticulum functionsynthesizes proteins and transports them to Golgi apparatus
  10. 10smooth endoplasmic reticulum structuremembranous tubules and flattened sacs with no attached ribosomes
  11. 11smooth endoplasmic reticulum functionmanufactures lipids and carbohydrates; detoxifies harmful chemicals; stores calcium
  12. 12Golgi apparatus structure and functionS: flattened membrane sacs stacked on each other
    F: modifies, packages and distributes proteins and lipids for secretion or internal use
  13. 13lysosome structure and functionS: membrane-bound vesicle pinched off Golgi apparatus
    F: contains digestive enzymes
  14. 14peroxisome structure and functionmembrane-bound vesicle
    serves as one site of lipid and amino acid degradation; breaks down hydrogen peroxide.
  15. 15proteasomes structure and functiontubelike protein complexes in the cytoplasm
    break down proteins in the cytoplasm
  16. 16name the 9 cytoplasmic organellesribosome, rough and smooth endoplasmic reticulum, Golgi apparatus, lysosome, peroxisome, proteasomes, mitochondria, centrioles (?)
  17. 17mitochondria structurespherical, rod-shaped, or threadlike structures; enclosed by double membrane; inner membrane forms projections called cristae
  18. 18mitochondria functionmajor sites of ATP synthesis when oxygen is available
  19. 19centrioles structurepair of cylindrical organelles in the centrosome, consisting of triplets of parallel microtubules
  20. 20centrioles functionserve as centers for microtubule formation; determine cell polarity during cell division; form the basal bodies of cilia and flagella
  21. 21ciliaextensions of the plasma membrane containing doublets of parallel microtubules; 10 um in length
    F: move materials over the surface of cells
  22. 22flagellumextension of the plasma membrane containing doublets of parallel microtubules; 55 um in length
    F: in humans, propels spermatozoa
  23. 23microvilliextension of the plasma membrane containing microfilaments
    F: increase surface area of the plasma membrane for absorption and secretion; modified to form sensory receptors
  24. 24cytoplasmlocated between the plasma membrane and the nucleus
  25. 25organelleswithin cells specialized structures that perform specific functions
  26. 26name the 4 characteristic functions of the cellcell metabolism and energy use
    synthesis of molecules
    communication
    reproduction and inheritance
  27. 27cell metabolism and energy usechemical reactions within cells are called metabolic reactions and collectively known as cell metabolism; energy released from some metabolic reactions fuels cellular activities such as synthesis of molecules & muscle contraction or release energy as heat, which helps maintain body temp
  28. 28synthesis of moleculesdifferent cells synthesize diff molecules including proteins, nucleic acids, and lipids
    the structural and functional characteristics of cells are determined by the types of molecules they produce
  29. 29communicationcells produce and respond to chemical and electrical signals that allow them to communicate with one another
    e.g. nerve cells produce chem signals by which they communicate with muscle cells and muscle cells respond by contracting or relaxing
  30. 30reproduction and inheritancemost cells contain a complete copy of all the genetic info of the individual; this info ultimately determines the structural and functional characteristics of the cell; as a person grows, cells divide to produce new cells, each containing the same genetic info. specialized body cells called gametes are responsible for transmitting genetic info to the next generation.
  31. 31name the 13 common cells parts from table 3.1plasma membrane, nucleus, ribosome, rough and smooth endoplasmic reticulum, golgi apparatus, lysosome, peroxisome, proteasomes, mitochondria, centrioles, cilia, flagellum, microvilli
  32. 32name and describe the 4 types of microscopes used to view cellslight microscopes show general features of cells
    electron microscope study the fine structure of cells
    scanning electron microscope (SEM) revel features of the cell surface and surfaces of internal structures
    transmission electron microscope (TEM) allows us to see "through" parts of the cell and thus discover detailed aspects of cell structure
  33. 33membrane potentialan electrical charge difference across the plasma membrane resulting from the cell's regulation of ion movement into/out of the cell (there are more pos chrged ions immediately outside of plasma membrane and more neg chrgd ions and proteins inside, the outside of the plasma membrane is positively charged compared to the inside of the plasma membrane
  34. 34makeup of the plasma membrane45-50% lipids, 45-50% proteins, 4-8% carbohydrates
  35. 35glycolipds glycoproteins glycocalyx1. carbs + lipids
    2. carbs + proteins
    3. collection of glycoplipds, glycoproteins & carbs on the outer surface of the plasma membrane (often has molecules absorbed from extracellular environment so there's often no precise boundary between plasma membrane and extracellular environment)
  36. 36phospholipidsassemble to form a lipid bilayer, because they have a polar (charged) hydrophilic head and a nonpolar (uncharged) hydrophobic tail
    the hydrophilic heads are exposed to the aqueous extracellular and intracellular fluids of the cell, whereas the hydrophobic tails face one another in the interior of the plasma membrane
  37. 37fluid-mosaic model of the plasma membranesuggests that the plasma membrane is neither rigid nor statis in structure but is highly flexible and can change its shape and composition through time; provides important means f distributing molecules within the membrane, slight damage to the membrane can b e repaired b/c the phospholipds tend to reassemble around damaged site and close them, and it enables membranes to fuse with one another
  38. 38name the 2 major lipids of the plasma membranephospholipids and cholesterol
  39. 39cholesterol in the plasma membraneinterspersed among the phospholipids and accounts for about 1/3 of the total lipids in the membrane
    *the hydrophilic hydroxyl (-OH) group of cholesterol extends between the phospholipid heads to the hydrophilic surface of the membrane, wheas the hydrophobic part of the cholesterol molecule lies within the phydrophobic region of the phospholipids
    the amount of cholesterol in a particular plasma membrane is a mjor factor in determining its fluid nature since it limits the movement of phospholipds, providing stability to the membrane
  40. 40integral membrane proteinspenetrated deeplyinto the lipid bilayer, in many cases extending from one surface to the other
    consist of regions made up of amino acids with hydrophobic R groups and other regions with hydrophilic R groups (these lie on inner or outer surface of membrane or line channels within the phydrophobic part of the membrane
  41. 41peripheral membrane proteinsattached to either the inner or outer survaces of the lipid bilayer
  42. 42peripheral proteins may be bound tointegral membrane proteins or to the polar heads of the phospholipid molecules
  43. 43name the 5 roles membrane proteins can function asmarker molecules
    attachment proteins
    transport proteins
    receptor proteins
    enzymes
    *dependent on their 3D shape and chemical characteristics
  44. 44marker moleculescell surface molecules that allow cells to identify other cells or other molecules; mostly glycoproteins or glycolipds (e.g. sperm cell's recog of an oocyte; the minnue system's ability to distinguish between self and foreign cells)
  45. 45attachment proteinsintegral proteins that allow cells to attach to other cells or to extracellular molecules; many also attach to intracellular molecules
    includes cadherins (attach to other cells) and integrins (attach to extracellular molecules)
  46. 46integrinsproteins that attach cells to extracellular molecules; function in pairs of integral membrane proteins, which interact with intra and extra cellular molecules, and b/c of interaction w/intracellular molecules integrins also function in cellular communication
  47. 47transport proteins functionintegral proteins that allow ions or molecules to move from one side of the plasma membrane to the other
  48. 48transport proteins 3 characteristicsspecificity: each transport protein binds to & transports only a certain type of ion or molecule
    competition: result of similar molecules binding to the transport protein
    saturation: the rate of movement of molecules across the membrane is limited by the number of available transport proteins
  49. 49channel proteinsform passageways through the plasma membrane allowing specific ions or molecules to enter or exit; may be gated or nongated
  50. 50carrier proteins (transporters)move ions or molecules across the membrane; binding of specific chemical to carrier proteins causes changes in the shape of the carrier proteins; the carrier proteins then move the specific chemical across the membrane, release it and resume its original shape
  51. 51ATP-powered pumpsmove specific ions or molecules across the membrane; require ATP molecules to function
  52. 52receptor proteinsfunction as binding sites for chemical signals in the extracellular fluid; binding of chemical signals to receptors triggers cellular responses
  53. 53enzymescatalyze chemical reactions either inside or outside cells
  54. 54leak ion channels or nongated channelsalways open; are responsible for the plasma membrane's permeability to ions when the plasma membrane is at rest
  55. 55gated ion channels: ligand-gated ion channels & voltage-gated ion channelscan be open or closed; some open or close in response to chemical signals or ligands, which are small molecules that bind to proteins or glycoproteins- therse are ligand-gated ion channels; others open or close when there's a change in the membrane potential (voltage-gated ion channels)
  56. 563 classifications of movement of ions or molecules by carrier proteinsuniport: one specific ion or molecule
    symport: 2 different ions or molecules in the same direction
    antiport: 2 different ions or molecules in opposite directions across the plasma membrane
  57. 573 different types of carrier proteinsuniporters
    symporters
    antiporters
  58. 58ATP powered pumpstransport proteins that have binding sites for specific ions or molecules and for ATP; they are fuled by the breakdown of adenosine triphosphate (ATP) to adenosine diphosphate (ADP), which releases energy
  59. 59receptors linked to G protein complexes pt 11. G protein complex (has 3 proteins: alpha, beta, gamma) will only associate w/a receptor with a chemical signal bound to it; in its unassociated state the alpha subunit has GDP attached to it
  60. 60receptors linked to G protein complexes pt 2when a chemical signal binds to the receptor, it becomes associate with the G protein complex. GDP is released from the alpha subunit and a GTP is attached to it
  61. 61receptors linked to G protein complexes pt 3the G protein complex separates from the receptor and the alpha subunit separates from the other subunits. the alpha
  62. 62selective permeabilitythe plasma membrane only allows certain substances to pass through it
  63. 63diffusion: descriptionrandom movement of molecules results in net movement from areas of higher to lower concentration
  64. 64diffusion: substances transportedlipid-soluble molecules dissolve in the lipid bilayer and diffuse through it; ions and small molecules diffuse through membrane channels
  65. 65diffusion e.g.soxygen, carbon dioxide, and lipids such as steroid hormones, dissolve in the lipid bilayer, CI and urea move through membrane channels
  66. 66osmosis: descriptionwater diffuses across a selectively permeable membrane
  67. 67osmosis: substances transportedwater diffuses through the lipid bilayer
  68. 68osmosis: e.g.water moves from the intestines into the blood
  69. 69facilitated diffusion: descriptioncarrier proteins combine with substances and move them across the plasma membrane; no ATP is used; substances are always moved from areas of higher to lower concentration; it exhibits the characteristics of specificity, saturation and competition
  70. 70facilitated diffusion: substances transportedsome substances too large to pass through membrane channels and too polar to dissolve the lipid bilayer are transported
  71. 71facilitated difussion: e.g.sglucose moves by facilitated diffusion into muscle cells and adipocytes
  72. 72active transport: descriptionATP-powered pumps combine with substances and move them across the plasma membrane; ATP is used; substances can be moved areas of lower to higher concentration; it exhibits the characteristics of specificity, saturation and competition
  73. 73active transport: substances transportedsubstances too large to pass through channels and too polar to dissolve in the lipid bilayer are transported; substances that are acculumulate in concentrations higher on one side of the membrane than on the other are transported.
  74. 74active transport: e.g.sions, such as Na+, K+, and Ca2+, are actively transported
  75. 75secondary active transport: descriptionions are moved across the plasma membrane by active transport, which establishes an ion concentration gradient; ATP is required; ions then move back down their concentration gradient by facilitated diffusion, and another ion or molecule moves with the diffusion ion (symport) or in the opposite direction (antiport)
  76. 76secondary active transport: substances transportedsome sugars, amino acids, and ions are transported
  77. 77secondary active transport: e.g.sthere is a concentration gradient for Na+ into intestinal epithelial cells. this gradient provides the energy for the symport of glucose. as Na+ enter the cell, down their concentration gradient, glucose also enters the cell. in mnay cells, H+ are moved in the opposite direction of Na+ (antiport)
  78. 78endocytosis: descriptionthe plasma membrane forms a vesicle around the substances to be transported, and the vesicle is taken into the cell; this requires ATP; in receptor-mediated endocytosis, specific substances are ingested
  79. 79endocytosis: substances transportedphagocytosis takes in cells and solid particles; pinocytosis takes in molecules dissolved in liquid
  80. 80endocytosis: exampleimmune system cells called phagocytes ingest bacteria and cellular debris; most cells take in substances through pinocytosis
  81. 81exocytosis: descriptionmaterials manufactured by the cell are packaged in secretory vesicles that fuse with the plasma membrane and release their contents to the outside of the cell; requires ATP
  82. 82exocytosis: substances transportedproteins and other water-soluble molecules are transported out of cells
  83. 83exocytosis: examplesdigestive enzymes, hormones, neurotransmitters, and glandular secretions are transported, and cell waste products are eliminated
  84. 84Name the 3 passive transport mechanismsdiffusion, osmosis, facilitated diffusion
  85. 85Name the 4 active transport mechanismsactive transport, secondary active transport
    vesicular transports:
    endocytosis, exocytosis
  86. 86solutions consist ofone or more substances called solutes dissolved in the predominant liquid or gas, which is the solvent
  87. 87simple definition of diffusionthe movement of solutes from an area of higher solute concentration to an area of lower solute concentration
  88. 88concentration gradientthe concentration difference between 2 points, divided by the distance between the 2 points is called the concentration gradient
  89. 89Solutes diffuse down or up their concentration gradient?they diffuse down their concentration gradient, meaning from a higher to a lower solute concentration until an equilibrium is achieved.
  90. 90viscositymeasure of a fluid's resistance to flow
  91. 91the greater the concentration gradient the greater...the rate of diffusion of a solute down that gradient
  92. 92osmosis simple definitiondiffusion of water across a selectively permeable membrane (water diffuses from the less concentrated solution (fewer solutes, more water) into the more concentrated solution (more solutes, less water)
  93. 93selectively permeablemeans that the membrane allows water but not all the solutes dissolved in the water to diffuse through it
  94. 94aquaporinswater channel proteins; increase membrane permeability to water in some cell types, such as kidney cells
  95. 95osmotic pressurethe force required to prevent water from moving by osmosis across a selectively permeable membrane
  96. 96isosmostic2 solutions with the same concentration of solute particles and therefore have the same osmotic pressure (even if the solutes are different types of particles)
  97. 97hyperosmotichas greater concentration of solute particles and therefore greater osmotic pressure than another solution
  98. 98hyposmotichas lower concentration of solute particles and therefore less osmotic pressure than another solution
  99. 99isotonicwhen a cell placed into a solution neither shrinks nor swells (with water) the solution is isotonic (can be isosmotic as well, meaning the solution has the same concentration of solutes and water as within the cell)
  100. 100tonicitywhen a cell maintains its internal tension or tone (neither shrinks nor swells)
  101. 101hypertoniccell placed in a solution and water moves out of the cell by osmosis, causing the cell to shrink the solution is hypertonic (and hyperosmotic as well-greater concentration of solutes than within the cell)
  102. 102hypotoniccell is placed in a solution and water moves into the cell by osmosis causing it to swell the solution is hypotonic (can be hyposmotic as well- more dilute than what's in the cell)
  103. 103crenationin red blood cells when water moves by osmosis from the cell into a hypertonic solution causing the cell to shrink
  104. 104lysisif cell is in a hypotonic solution, the water moves into the cell and it starts to swell, if it swells enough it can rupture in a process called lysis
  105. 105solutions injected into the bloodstream or tissues must be...isotonic, because if shrinkage or swelling of cells disrupts their normal function and can lead to cell death
  106. 106-osmoticrefers to the concentration of solutions
  107. 107-tonicterms refer to the tendency of cells to swell or shrink
  108. 108not all isosmotic solutions are isotonic example:a glycerol solution can be isosmotic with a cell, but because glycerol can diffuse across the plasma membrane when it does it causes the solute concentration of the cytoplasm to increase and its water concentration to decrease therefore water moves by osmosis into the cell, causing it to swell and the glycerol solution is both isosmotic and hypotonic.
  109. 109mediated transportprocess by which transport proteins mediate, or assist, the movement of large water-soluble molecules, electrically charged molecules or ions across the plasma membrane
  110. 110facilitated diffusioncarrier-mediated or channel-mediated passive membrane transport process that moves substances into or out of cells from higher to a lower concentration; doesn't require metabolic energy; the rate of transport is directly proportional to their concentration gradient up to the point of saturation (when all carrier proteins or channels are occupied) then the rate of transport remains constant at its maximum rate.
  111. 111active membrane transportmediated transport process that requires ATP; max rate depends on # of ATP-powered pumps in the plasma membrane and availability of adequate ATP; can move substances against their concentration gradients (i.e. from lower to higher); can accumulate substances on one side of the plasma membrane at concentrations many times greater than those on the other side. it can also move substances from higher to lower concentrations
  112. 112sodium-potassium pump (Na+-K+)moves Na+ out of cells and K+ into cells; result is higher concentration of Na+ outside of cell and higher concentration of K+ inside cell; also called sodium-potassium ATP-ase (b/c it uses ATP)
  113. 113secondary active transportinvolves the active transport of an ion, such as sodium, out of a cell, est. a concentration gradient, with a higher concentration of the ions outside of the cell. the tendency for the ions to move back into the cell provides the energy necessary to move a different ion or some other molecule into the cell
  114. 114glucose example of secondary active transportrequires 2 transport proteins: 1) a Na+-K+ pump actively moves Na+ out of the cell and 2) a carrier protein facilitates the movement of Na+ and glucose into the cell. both Na+ and glucose are necessary for the carrier protein to function. the concentration gradient for Na+ provides energy required to move glucose against its concentration gradient.
  115. 115vesicular transportmovement of larger volumes of substances across the plasma membrane through the formation or release of vesicles, membrane-bound sacs, in the cytoplasm. includes endocytosis and exocytosis; requires ATP and is therefore an active membrane transport process; involves bulk movement into the cell doesn't have the same degree of specificity or saturation as other forms of active membrane transport
  116. 116endocytosisuptake of material through the plasma membrane by formation of a vesicle; portion of plasma membrane wraps around a particle or droplet and fuses so that it's surrounded by a membrane; that portion of the membrane then "pinches off" so the enclosed particle/droplet is within the cytoplasm of the cell and the plasma membrane is left intact
  117. 117endocytosis includes...phagocytosis "cell eating": solid particles are ingested and phagocytic vesicles are formed; white blood cells and some other cell types phagocytize bacteria, cell debris and foreign particles; therefore it's important in eliminating harmful substances fromt he body
  118. 118endocytosis also includes...pinocytosis (cell drinking): differs from phagocytosis in that smaller vesicles form and they contain molecules dissolved in liquid rather than particles;
  119. 119endocytosis can exhibit specificitycells that phagocytize bacteria and necrotic tissue don't phagocytize healthy cells
  120. 120receptor-mediated endocytosisthe plasma membrane may contain specific receptor molecules that recognize certain substances and allow them to be transported into the cell by phagocytosis or pinocytosis; the receptor sites combine only with certain molecules; this increases the rate at which the cells take up specific substances (e.g.s cholesterol and growth factors can be taken into a cell by receptor-mediated endocytosis)
  121. 121hypercholesterolemiacommon genetic disorder characterized by the reduction in or absence of low-density lipoprotein (LDL) receptors on cell surfaces, which interferes with the receptor-mediated endocytosis of LDL cholesterol; as a result of inadequate cholesterol uptake, cholesterol synthesis within these cells isn't regulated & too much cholesterol is produced, accumulates in blood vessels, resulting in atherosclerosis, which can cause heart attacks or strokes.
  122. 122exocytosisin some cells secretions accumulate within vesicles, these secretory vesicles then move to the plasma membrane where they fuse with it and the vesicle contents are expelled from the cell (e.g. secretion of digestive enzymes by pancreas and secretion of mucus by salivary glands)
  123. 123cytoplasmthe cellular material outside the nucleus but inside the plasma membrane, is about half cytosol and half organelles
  124. 124cytosolfluid portion of the cytoplasm, which contains the cytoskeleton and cytoplasmic inclusions; the fluid portion is a colloid, a viscous solution containing dissolved ions and molecules as well as suspended molecules, especially proteins (many of which are enzymes that catalyze the breakdown of molecules for energy or the synthesis of sugars, fatty acids, nucleotides, amino acids and other molecules
  125. 125cytoskeletonsupports the cell and holds the nucleus and other organelles in place; responsible for changes in cell shape and the movement of cell organelles; consists of 3 groups of proteins: microtubules, actin filaments, and intermediate filaments
  126. 126microtubuleshollow tubes composed primarily of protein units called tubulin; about 25 nm in diameter, wall 5 nm thick and vary in length but normally several micrometers (um) long; help provide support and structure to the cytoplasm of the cell like internal scaffolding; involved in cell division and in the transport of intracellular materials; form essential components of certain organelles such as centrioles, spindle fibers, cilia, and flagella
  127. 127actin filaments (microfilaments)small fibrils, about 8 nm in diameter that form bundles, sheets or networks in the cytoplasm; have a spiderweb-like appearance; provide structure to the cytoplasm and mechanical support for microvilli, support the plasma membrane and define the shape of the cell; changes in cell shape involve the breakdown and reconstruction of actin filaments, these changes in shape allow some cells to move about; muscle cells contain a large # of highly organized actin filaments, which are responsible for their contractile capabilities.
  128. 128intermediate filamentsprotein fibers about 10 nm in diameter that provide mechanical strength to cells. e.g. they support the extensions of nerve cells, which have a very small diameter but can be up to a meter in length
  129. 129cytoplasmic inclusionscytosol contains these, which are aggregates of chemicals either produced or taken in by the cell. e.g. lipid droplets or glycogen granules store energy-rich molecules; hemoglobin in red blood cells transports oxygen; lipochromes are pigments that increase with age; melanin colors the skin, hair and etes; dust, minerals and dyes can also accumulate in the cytoplasm
  130. 130organellesstructures within cells that are specialized for particular functions e.g. manufacturing proteins or producing ATP
  131. 131cytoplasmic organellesall the organelles except the largest (the nucleus)
  132. 132nucleus generallarge, membrane-bound structure usually located near the center of the cell; may be spherical, elongated, or lobed depending on the cell type; all body cells have a nucleus at some point in their life cycle, although some lose their nuclei as they develop (e.g. red blood cells); others cells (skeletal muscle cells and certain bone cells called osteoclasts) contain more than 1 nucleus
  133. 133structure of nucleusconsists of nucleoplasm surrounded by a nuclear envelope composed of 2 membranes separated by a space; at many points on the surface of the nuclear envelope the inner and outer membranes fuse to form porelike structures called nuclear pores; molecules move between the nucleus and the cytoplasm through these openings
  134. 134DNA where founddeoxyribonucleic acid is mostly found within the nucleus, but small amounts also in mitochondria
  135. 135chromosomesnuclear DNA and associated proteins (including histones which are important for the structural organization of DNA and other proteins that regulate DNA function) are organized into these discrete structures
  136. 136histonesproteins wrapped with DNA in chromosomes that are important for the structural organization of DNA
  137. 137chromatinduring most of the cell's life cycle the chromosomes are dispersed throughout the nucleus as these delicate filaments
  138. 138when are chromosomes formedduring cell division the dispersed chromatin becomes densely coiled forming chromosomes
  139. 139DNA determines what...DNA determines the structural and functional characteristics of the cell by specifying the structure of proteins; it does so by specifying the sequence of their amino acids
  140. 140DNA functions by means of...DNA is a large molecules that doesn't leave the nucleus but functions by means of an intermediate, RNA (ribonucleic acid), which can leave the nucleus through nuclear pores. DNA determines the structure of messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA)
  141. 141genea sequence of nucleotides in a DNA molecule that specifies an RNA molecule
  142. 142cells with nuclei vs withoutb/c mRNA synthesis occurs within the nucleus, cells without nuclei accomplish protein synthesis only as long as the mRNA produced before the nucleus degenerates remains functional; e.g. red blood cells lack nuclei (they're expelled from cells before they enter the blood) therefore red blood cells survive without a nucleus for about 120 days and must be continually replaced; many cells with nuclei such as nerve and skeletal muscle cells, potentially survive as long as the person is alive
  143. 143nucleolusdense region within the nucleus that lacks a surrounding membrane; usually 1 nucleolus exists per nucleus, but several nucleoli may be seen in the nuclei of rapidly dividing cells; it incorporates portions of chromosomes that contain DNA from which rRNA is produced; within it subunits of ribosomes are manufactured
  144. 144ribosomessite of protein synthesis; composed of a large subunit and a small subunit; the ribosomal subunits consist of rRNA produced in the nucleus and proteins produced in the cytoplasm; ribosomal subunits assembled separately in the nucleolus- they then travel through the nuclear pores into the cytoplasm, where they assemble with mRNA to form the functional ribosome during protein synthesis
  145. 145free ribosomesfound free in the cytoplasm and primarily synthesize proteins used inside the cell
  146. 146attached ribosomesattached to the endoplasmic reticulum (making it rough); produce integral membrane proteins and proteins that are secreted from the cell
  147. 147endoplasmic reticulumthe outer membrane of the nuclear envelope is continuous series of membranes distributed throughout the cytoplasm that are referred to collectively as the endoplasmic reticulum; consists of broad, flattened, interconnecting sacs and tubules
  148. 148cisternaeinterior spaces of the sacs and tubules of the ER that are isolated from the rest of the cytoplasm
  149. 149rough endoplasmic reticulumendoplasmic reticulum with ribosomes attached to it; ribsosomes are the site of protein synthesis and modification for use as integral membrane proteins and for secretion into the extracellular space; cells with abundant rough ER synthesize large amounts of protein, which are secreted for use outside the cell
  150. 150smooth endoplasmic reticulumno attached ribosomes; manufactures lipids such as phospholipids, cholesterol and steroid hormones as well as carbs; enzymes required for lipid synthesis are associated with the membranes of the smooth endoplasmic reticulum; also participates in detoxification, the processes by which enzymes act on chemicals and drugs to change their structure and reduce their toxicity. smooth ER of skeletal muscle stores the calcium ions that function in muscle contraction
  151. 151Golgi apparatuscomposed of flattened, membranous sacs, containing cisternae, stacked on each other like dinner plates; can be thought of as a packaging and distribution center b/c it modifies, packages and distributes proteins and lipids manufactured by the rough and smooth endoplasmic reticula
  152. 152transport vesiclesproteins produced at the ribosomes in rough ER enter the ER and then are packaged into transport vesicles that move to the Golgi apparatus, fuse with the Golgi apparatus membrane and release the protein into the Golgi apparatus cisterna
  153. 153how the Golgi apparatus modifies, packages and distributes proteinsit concentrates and in some cases, chemically modifies the proteins by synthesizing and attaching carb molecules to the proteins to form glycoproteins or by attaching lipids to form lipoproteins. the proteins are then packaged into vesicles that pinch off from the margins of the GA and are distributed to various locations
  154. 154Golgi apparatus most highly developed in cells thatsecrete large amounts of protein or glycoproteins such as cells in the salivary glands and the pancreas
  155. 155secretory vesiclesmembrane-bound vesicles that pinch off from the GA move to the surface of the cell, their membranes fuse with the plasma membrane and the contents of the vesicles are released to the exterior by exocytosis; the membranes are then incorporated into the plasma membrane
  156. 156the contents of secretory vesicles frequently aren't released until...the cell receives a signal; e.g. secretory vesicles containing the hormone insulin don't release it until the concentration of glucose in the blood increases and acts as a signal
  157. 157lysosomesmembrane-bound vesicles that form at the GA; contain a variety of hydrolytic enzymes that function as intracell.ular digestive systems. vesicles taken into the cell fuse with the lysosomes to form one vesicle and to expose the endocytized materials to hydrolytic enzymes; various enzymes within lysosomes digest nucleic acids, proteins, polysaccharides, and lipids; certain white blood cells have large #s that contain enzymes to digest phagocytized bacteria; also digest the organelles of the cell that are no longer functional (autophagy); in other cells they move into the plasma membrane and the enzymes are secreted by exocytosis
  158. 158peroxisomesmembrane-bound vesicles that are smaller than lysosomes; contain enzymes that break down fatty acids and amino acids; hydrogen peroxide, which can bet toxic to the cell, is a by-product of that breakdown; they also contain the enzyme catalase, which breaks down hydrogen peroxide to water and oxygen; cells that are active in detox such as liver and kidney cells have many peroxisomes
  159. 159centrosomea specialized zone of cytoplasm close to the nucleus, is the center of microtubule formation in the cell; contains two centrioles
  160. 160centriolesmall cylindrical organelle about .3-.5 um in length and .15 um in diameter; 2 centrioles are normally oriented perpendicular to each other within the centrosome; its wall is composed of nine evenly space, longitudinally oriented, parallel units, or triplets; each unit consists of 3 parallel microtubules joined together
  161. 161the centrosome is closely involved in...determining cell shape and movement through its control of microtubule formation; the microtublues extending from the centrosomes are very dynamic- constantly growing and shrinking
  162. 162cell division and centrosomesbefore cell division the 2 centrioles in the centrosome double in number; the centrosome divids into 2; and one centrosome, containing 2 centrioles, moves to each end of the cell; microtubules called spindle fibers extend out in all directions from the centrosome; the microtubulues grow & shrink more rapidly than in a nondividing cell; if the extended end of a spindle fiber comes into contact w/a chromosome, it attaches to it and stops growing/shrinking; eventually, spindle fibers from each centrosome bind to all the chromosomes and the spindle microtubules facilitate the movement of chromosomes toward the 2 centrosomes
  163. 163ciliastructures that project from the surface of cells & can move; vary in # from 1 to thousands per cell; cylindrical in shape, measuring about 10 um in length .2 um in diameter. the shaft of each cilium is enclosed by the plasma membrane; each cilium contains 2 centrally located microtubules & 9 peripheral pairs of fused microtubules (the 9+2 arrangement) that extend from the base to the tip of the cilium.
  164. 164how cilia are able to moveresults when the microtubules move past each other, requires ATP. dynein arms (proteins connecting adjacent paris of microtubules) push the microtubules past each other.
  165. 165basal bodya modified centriole located in the cytoplasm at the base of the cilium
  166. 166how and why cilia movenumerous on surface cells that line the respiratory tract & female reproductive tract; in theses regions cilia move in a coordinated fashion, w/ a power stroke in 1 direction and a recovery stroke in the opposite direction. their motion moves materials over the surface of the cells; e.g. cilia in trachea move mucus containing trapped dust particles upward and away from the lungs
  167. 167flagellahave a structure similar to cilia, but they are longer (45 um); sperm cells only human cells w/flagella and usually only 1 per cell. cilia move small particles across the cell surface, flagella move the entire cell, instead of a power and recovery stroke like cilia they move in a wavelike fashion
  168. 168microvillicylindrically shaped extensions of the plasma membrane about .5-1 um in length and 90 nm in diameter; normally each cell has many microvilli & they increase the cell surface area; microvilli are 1/10 to 1/20 the size of cilia; don't move and they're supported w/actin filaments, not microtubules; found on intestine, kidney and other areas where absorption is an important function; incertain locations of the body they're highly modified to function as sensory receptors; e.g. elongated microvilli in hair cells of the inner ear respond to sound
  169. 169genesfunctional units of heredity (the transmission of genetic traits from parent to offspring); each gene is a segment of a DNA molecule that specifies the structure of an RNA molecule. this RNA can be functional on its own or it can produce a protein
  170. 170gene expressionthe production of RNA &/or proteins from the info stored in DNA
  171. 171transcriptionsynthesis of mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA) based on the nucleotide sequence in DNA, which makes a copy of a small part of the stored info in DNA
  172. 172how transcription occurs at the nucleotide leveladenine of RNA aligns w/thymine of DNA,
    cytosine of RNA aligns w/ guanine of DNA
    guanine of RNA aligns w/cytosine of DNA
    uracil of RNA aligns w/adenine of DNA
  173. 173RNA polymeraseis an enzyme that synthesizes the complementary RNA molecule from DNA
  174. 174promoterRNA polymerase attaches to this DNA nucleotide sequence by associating with transcription factors (proteins) & this causes a portion of the DNA molecule to unwind exposing the nucleotide sequence for that region of th etemplate strand
  175. 175transcription factorsproteins that RNA polymerase must first associate with in order to interact with DNA
  176. 176transcription stepsRNA polymerase attaches to a DNA nucleotide sequence called a promoter with association w/transcription factors; causes portion of DNA molecule to unwind exposing nucleotide sequence for that region of template strand; complementary RNA nucleotides then align w/DNA nucleotides of the template strand. RNA nucleotides are cobined by dehydration reactions catalyzed by RNA polymerase to form RNA, only small portion of DNA unwinds at any one time, as complementary nucleotides are added to the RNA, RNA polymerase moves along the DNA, unwinding the next portion, while the previously unwound section of DNA strands winds back together, when RNA polymerase encounters a DNA nucleotide sequence called the terminator it detaches from the DNA releasing the newly formed RNA, the type of RNA that makes proteins is called a messenger RNA (mRNA)
  177. 177generegion of a DNA molecule between the promoter and termination of transcription is a gene.
  178. 178exonsregions of the mRNA that code for proteins
  179. 179intronsnon-protein-coding regions of mRNA
  180. 180pre-mRNAan mRNA that contain introns (non-protein-coding regions)
  181. 181functional mRNAwhen introns have been removed from pre-mRNA & the exons are spliced together, only exons (protein coding portions) are left
  182. 182posttranscriptional processingmodifications made to pre-mRNA before it leaves the nucleus:
    introns removed, 7-methylguanosine cap added to one end of mRNA, a poly-A tail (series of adenine nucleotides) added to other end. these modifications to the ends of the mRNA ensure that it travels from the nucleus to the cytoplasm and interacts w/ribosomes during translation
  183. 183alternative splicingwhen various combos of exons are incorporated into mRNA. which exons and how many are used can vary between cells of different tissues, resulting in different mRNAs transcribed from the same gene. it allows a single gene to produce more than one specific protein; however the various proteins usually have similar functions in different tissues. in humans nearly all mRNAs undergo alt. RNA splicing
  184. 184genetic codeinfo contained in mRNA. it's carried in sets of 3 nucleotide units called codons
  185. 185codona 3 nucleotide unit that specifies an amino acid during translation
    e.g. the codon GAU specifies the amino acid aspartic acid
    some codons act as signals during translation
  186. 186# of amino acids commonly found in proteins # of possible codons & this means...20
    64
    this means that an amino acid can have more than one codon
    e.g. codons for arginine include: CGA, CGG, CGU, CGC
  187. 187start codonsignals the beginning of translation
  188. 188stop codonsignals the end of translation
  189. 189translationsynthesis of a protein at the ribosome in response to the codons of mRNA. requires mRNA, tRNA and ribosomes (ribosomes consist of ribosomal RNA (rRNA) and proteins)
  190. 190function of tRNAto match a specific amino acid to a specific codon of mRNA. to do this this one end of each kind of tRNA combines w/a specific amino acid
  191. 191anticodonpart of the tRNA that consists of 3 nucleotides and is complementary to a particular codon of mRNA and can only pair with its matched codon
  192. 192function of ribosomesribosomes align the codons of the mRNA w/the anticodons of the tRNA and then enzymatically join the amino acids of adjacent tRNA molecules. the mRNA moves through the ribosome one codon at a time. with each move a new tRNA enters the ribosome and the amino acid is linked to the growing chain forming a polypeptide
  193. 193polyribosomeafter a ribosome uses the inital part of mRNA another ribosome can attach to the mRNA and begin to make a protein. the resulting cluster of ribosomes attached to the mRNA is called a polyribosome. each ribosome in a polyribosome produces an identical protein. they're an efficient way to produce many copies of the same protein using a single mRNA molecule
  194. 194proproteinsmany proteins are longer when they're first made than in their final, functional state and these proteins are called proproteins. the extra piece of the molecule is cleaved off by enzymes to make the proprotein into a functional protein
  195. 195proenzymeswhat the proprotein of an enzyme is called (i.e. longer non-functional version of an enzyme). to prevent the newly made enzyme from digesting the cell that made them they are made as proenzymes and aren't coverted to active enzymes until they reach a protected region of the body, such as inside the small intestine where they're functional
  196. 196post-translational processinge.g.s: many proteins have side chains such as polysaccharides added to them
    some proteins are composed of 2 or more amino acid chains that are joined after each chain is produced on separate ribosomes
  197. 197regulation of gene expressionas cells become specialized part of the DNA is no longer transcribed, while other segments become more active
    e.g. DNA coding for hemoglobin isn't expressed in most cells, but in developing red blood cells the DNA coding for hemoglobin is transcribed and its synthesis occurs rapidly
  198. 198gene expression fluctuatesin response to changes in signals from within and outside of the cell. regulatory molecules that interact w/nuclear proteins can increase or decrease the transcription rate of specific DNA segments
  199. 199cell life cycleincludes the changes a cell undergoes from the time it's formed until it divides to produce 2 new cells. it has 2 states: interphase and cell division (cell division: mitosis and cytokinesis)
  200. 200interphaseit's the phase between cell divisions. nearly all of the life cycle of a typical cell is spent in interphase. cell carries out metabolic activities necessary for life and performs its specialized functions. it also prepares to divide. this prep includes an increase in cell size as many cell components double in quantity & a doubling of the DNA content. centrioles within centrosome are also duplicated. therefore when the cell divides each new cell receives the organelles and DNA necessary for functioning

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2 Science Flashcards on Chapter 3 Anatomy and Physiology, created by Johanna Keifert on 23/01/2017.
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