Unit 3 Flashcards

Question

active membrane processes

Answer 1

movement across cell membrane requiring ATP molecules can't enter passively because: - not lipid soluble - too large - going against concentration gradient 1. active transport - symport - antiport 2. cytosis - endocytosis - exocytosis

Answer 2

carrier protein + ATP required to move: - Na, K, Ca2, Mg2 a. symport - substances moved in same direction b. antiport - some substances in same direction, some in opposite

Answer 3

- critical for maintaining fluid balance - critical for normal functioning of irritable cells (those which create energy for active transport through respiration) ie. myofibrils, neurons

Answer 4

brings nutrients into cell + ejects waste - needs ATP a. endocytosis - transports large particles/liquids into cell by engulfing them - phago, pino, or receptor-mediated i. phagocytosis: cell eats solid material by making a vesicle ('phagosome') - marcophage: debris, dead cells, invaders - phagosome fuses with lysosomes for digestion - white blood cells handle bacteria and viruses - pseudopodia: macrophages + WBC move by amoeboid motion ii. pinocytosis: cells engulfs liquid material through infolding of plasma membrane - in cells lining small intestine and renal tubules iii. receptor-mediated endocytosis: for cells with specific proteins in their plasma membranes - eg. 'ligands' bind to specific receptors making a vesicle known as 'coated pit' - eg. insulin binding to insulin receptors b. exocytosis - export intracellular substances into extracellular space - substances packaged in vesicles by ER + golgi body - vesicles move through cytoplasm -> cell surface -> fuse w/plasma membrane -> release contents into extracellular fluid - eg. neurons release acetylcholine - eg. endothelial cells lining trachea secrete mucus - eg. mast cells release thousands of granules of histamine during alleric reaction - excretion = waste - secretion = manufactured

Answer 5

AKA voltage - potential electrical energy created by separation of opposite charges (changes in distribution of charged particles on either side of cell membrane) - plasma membrane more permeable to some molecules than others - ALL cells have membrane potential (normal values -20 to -22 millivolts/mV) - principal ions: K and Na - normally more K inside a cell, moves out by diffusion - Na more outside cell, can't easily move in, occurs at every cycle of active transport - 3 Na exit for every 2 K entering - 'resting membrane potential' altered by: - changes in environmental tonicity, osmotic pressure, temperature, or contact with neighboring cells - these changes alter flow of metabolites (alters behaviour of structural and enzymatic proteins) - eg. muscle cells contracting due to changes in membrane potential

Answer 6

nutrient: substance from food used to carry out body functions 1. water 2. carbohydrates 3. lipids 4. proteins 5. vitamins 6. minerals

Answer 7

carbohydrates lipids proteins

Answer 8

water vitamins minerals

Answer 9

body can't manufacture, must get from diet eg. taurine in meat, cats need to prevent retinal degeneration, dilated cardiomyopathy, decreased reproductive function

Answer 10

most important nutrient - amount needed = daily energy requirement - from food, drink, oxidizing proteins/fats/carbs

Answer 11

p. 418-428

Answer 12

monosaccharide - simplest dietary carb - makes ATP through glycolysis - excess converted to glycogen -> stored in liver OR converted to fat + stored in adipose

Answer 13

saturated: - single bonds b/w C, can accommodate greatest # of H - long chains eg. meat and dairy unsaturated: - 1+ double C bonds, less room for H - liquid at room temp - monounsaturated: olive, peanut oil - polyunsaturated: corn, soybean, safflower oil - liver can convert one fatty acid into another essential: can't be synthesized - linoleic - linolenic - arachidonic acid

Answer 14

2x as much potential energy as proteins or carbs. - make food taste good - stave off hunger - help absorb fat-soluble vitamins: A D E K - insulate when stored, protect and cushion vital organs - rebuilt by liver -> form different kinds of triglycerides - major energy source for hepatocytes and skeletal muscle cells

Answer 15

for body to make a new protein, all of the needed amino acids (essential + non) must be present in the cell - in sufficient quantity - present at same time if one is missing, the protein can't be made

Answer 16

can't be made at all or fast enough for body's tissue maintenance eg. taurine, arginine, glycine

Answer 17

complete/'ideal': - all essential amino acids needed by species to meet its metabolic requirements (meat, eggs, dairy) complements: - when ingested together, contain all amino acids (legumes and grains) biologic value: - % of absorbable protein available for body functions (not same as protein content) - quality of protein improves when feed is not overprocessed/overheated ruminant digestion of protein: - facilitated by microbes - microbial-made protein has consistent quality regardless of source (lower-quality feed is improved by microbial metabolism) - ability to convert non-protein sources of N into protein

Answer 18

amino acids can't be stored. if not used to make protein immediately then: - oxidized by cell for energy - converted to carbs or fats - rate of protein synthesis = rate of protein breakdown/loss - positive balance: more protein incorporated into tissue than is used to make ATP (healing, pregnancy, growth) - negative balance: protein breakdown exceeds amount incorporated into tissue (stress, infection, poor dietary protein) - N from protein breakdown packaged into 'urea' in liver -> excreted by kidney - urea measured by blood urea nitrogen (BUN) test

Answer 19

essential for life - don't make energy - not broken into building-block units not made in body EXCEPT: - D (made in skin) - K + biotin (made by bacteria in intestine) - A (made by converting beta carotene) function: - co-enzymes/parts of co-enzymes - molecular structure is the 'key' to activate an enzyme eg. riboflavin + niacin breakdown glucose water-soluble vitamins: - absorbed through GI wall - very few stored (hypervitaminosis would be rare), excess excreted in urine ex. C, B (except B12) fat-soluble vitamins: - bind to ingested lipids before they're absorbed with food - stored in body (except K), hypervitaminosis can occur ex. A, D, E, K

Answer 20

generated when carbs, proteins, and fats are oxidized as part of normal metabolism - potentially harmful - disarmed by antioxidants (vitamins A, C, E)

Answer 21

inorganic substances essential for life - non-energy - work with other nutrients for body function 3 classes: 1. macro 2. micro 3. trace elements

Answer 22

forming and breaking chemical bonds 4 types: 1. redox 2. synthesis 3. decomposition 4. exchange factors influencing: 1. concentration of reactants 2. temperature of environment 3. activation energy 4. catalyst presence

Answer 23

an e- removed during oxidation of atom/molecule is transferred to another atom/molecule -> the one that gains an e- is 'reduced' -> the one that loses an e- is 'oxidized' a) oxidation - combine with O, lose H and e- b) reduction - combine with H, gain e-, lose O

Answer 24

smaller molecules bond to form larger complex molecules - anabolic process in body eg. amino acids join to form a protein molecule

Answer 25

bonds in large molecules broken to make smaller less complex molecules - catabolic process eg. glycogen breaking down into glucose

Answer 26

bonds broken + made eg. ATP transfers 1 phosphate to glucose -> 'glucose-phosphate'

Answer 27

cell metabolism where nutrients broken down to make energy - energy stored in bonds of ATP molecule -> transported where needed stages: 1. GI tract - broken down in stomach -> small intestine -> nutrients absorbed by cells that line small intestine -> nutrients pass to blood/lymph -> carried to organs + tissues -> may go to liver for further metabolism - enzymes help - hydrolysis into building blocks: - carbs break down -> monosaccharides - fats break down -> fatty acids + glycerol - proteins break down -> amino acids 2. cytosol - anaerobic respiration in cell cytosol catabolizes nutrients - acetyl CoA transported through cytoplasm to mitochondria. 3. mitochondria - aerobic respiration in cell mitochondria (happens by PO4 attaching to ADP -> ATP) - ATP used to help cell carry energy - catabolic pathways of proteins, carbs, and fats transfer energy stored in nutrients into ATP

Answer 28

cell metabolism where stored energy makes new molecules from small components that catabolism made - biosynthetic process - growing cells need additional proteins for the expanded cell membranes and to perform vital functions metabolic turnover: - replacement molecules must be manufactured continuously dehydration synthesis: - part of anabolism - opposite of hydrolysis - monosaccharides assembled into polysaccharide chains (1 mono + 1 mono = 1 di + water) - fatty acids + glycerol assemble fat molecules - amino acid chains assemble proteins

Answer 29

- energy supplied to cells by nutrient breakdown - energy released when bonds broken storage forms: ATP, NADH, FADH2

Answer 30

- metabolism is a multi-enzyme sequence of events - reactions are highly specific, enzymes initiate and control metabolism - each enzyme reacts with ONE particular molecule (substrate) to produce new molecule (product) - product of one step = substrate of next - cofactor: - nonprotein that might be needed to help complete a reaction - completes the shape of a binding site eg. iron, zinc, copper, magnesium, potassium, calcium ions - co-enzymes: - nonprotein organic molecules that can be co-factors - often vitamins/vitamin-derived - can be temporary/permanently bound to enzyme eg. NAD, acetyl-coenzyme A, FAD

Answer 31

depends on molecular shape of enzyme - enzymes remain unaltered from reactions. - end in '-ase', often named for the substrate the act upon eg. phosphotransferase moves PO4 group active site = region where it binds to substrate factors affecting enzyme activity: - enzyme concentration (effect on rate directly proportional) - substrate concentration (rate increases until enzyme is saturated) - temperature (rate increases until denaturation of enzyme) - pH (most max out at pH 7 and denature at pH extremities except pepsin [1.5 optimum]) eg. shape of binding site in some enzymes affected by temperature ('thermolabile enzymes'), such as siamese coat color enzyme which doesn't function well in heat so only its extremities get the dark coloring

Answer 32

- enzymes act as catalyst - speed up reactions by lowering activation energy - this increased rate is essential to life eg. Co2 (waste from respiration) needs to be moved out of body -> carbonic anhydrase combines with CO2 -> 'carbonic acid' + bicarbonate ions

Answer 33

inhibitor: any substance that can decrease rate of enzyme-catalyzed reaction - many poisons, some medicines - some inhibitors provide internal regulation of cellular metabolism 2 kinds: 1. reversible - binds to an enzyme but can be removed a) competitive - competes w/substrate for binding at active site of enzyme - similar molecular structure to the normal substrate - reversed by increasing concentration of normal substrate - competition won by whichever is in greater concentration eg. sulfa drugs eg. folic acid needed by bacteria is synthesized from p-aminobenzoic acid, which resembles sulfanilamide -> sulfanilamide competes for active site -> synthesis of folic acid slowed/stopped -> bacteria prevented from multiplying b) noncompetitive - binds to enzyme at location other than active site - no resemblance to normal enzyme substrate - interactions makes shape of enzyme + active site change - enzyme no longer binds normal substrate or it binds improperly so creation is not catalyzed - more substrate does NOT reverse inhibition eg. isoleucine feedback inhibitor 2. irreversible: - covalent bond w/ functional group of enzyme - makes enzyme inactive eg. many poisons.... eg. cyanide ion: - interferes w/ cytochrome oxidase - blocks mitochondrial e- transport chain - stops aerobic cellular respiration - death in minutes. - antidote: sodium thiosulfate (converts cyanide ion to thiocyanate that doesn't bind cytochrome oxidase) eg. heavy metals (mercury, lead) - combine sulfhydryl groups on enzymes - can cause neurological damage - treated with chelating agents (substance that combines with metal and holds it tightly) eg. antibiotics (penicillin) - inhibit enzymes essential to life processes of bacteria - interferes w/ transpeptidase which is needed for bacterial cell wall construction

Answer 34

enzymes must be controlled (organism responding to changing conditions and cellular needs) 3 control mechanisms: 1) activation of zymogens - enzymes may be synthesized as inactive precursors called zymogens or proenzymes - stored in inactive state - when needed, zymogen is released and activated at location of reaction - activation usually involves cleavage of peptide bones of zymogen eg. active enzyme 'thrombin' -> zymogen 'prothrombin' 2) allosteric regulation - combination of enzyme with compound ('modulator') that changes shape - modulators may be: activators (increase activity) OR inhibitors (decrease activity) - allosteric enzymes often located at key control points in cellular processes eg. synthesis of isoleucine - 5 steps - product isoleucine binds to enzyme at 1st step -> inhibits enzyme -> no excess isoleucine produced -> when isoleucine level lowers the enzyme will be more active -> more isoleucine synthesized ---> this is an eg. of 'feedback inhibition': a process where the end product of a pathway inhibits an earlier step in the process 3) genetic control - enzyme induction: synthesis of an enzyme in response to cellular need - allows organism to adapt to environmental changes eg. regulation of gluconeogenesis (activity of PEP carboxykinase increased during fasting, starvation and diabetes mellitus due to enzyme induction by glucagon)

Answer 35

- certain enzymes normally found only inside cells -> released into blood/fluid when cells damaged - changes in blood serum levels of specific enzymes can be used to clinically detect cell damage or uncontrolled growth - measurements of enzyme concentrations is a major diagnostic tool for heart, liver, pancreas, and bone diseases eg. - alkaline phosphatase: liver/bone - amylase: pancreas - lipase: acute pancreatitis - alanine transaminase: hepatitis - aspartate transaminase: hepatitis/heart attack

Answer 36

slightly different form of the same enzyme produced by different tissues. - similar catalytic properties but different physical properties - assays for isozymes can pinpoint location and type of disease accurately