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99 Cards in this Set
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Define: metabolism
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sum of all chemical reactions occurring in a cell
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Define: catabolism
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(decomposition reaction) - breakdown of larger molecules into smaller ones
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Define: anabolism
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(synthesis reaction) - synthesis of large molecules from smaller ones
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What are three major types of metabolic reactions?
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1. hydrolysis and dehydration synthesis (condensation)
2. phosphorylation and dephosphorylation 3. oxidation-reduction |
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Define: hydrolysis
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add water molecules to break bonds between monomers (catabolic)
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Define: dehydration synthesis
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(condensation) - remove water molecule to join monomers (anabolic)
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Define: phosphorylation
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add phosphate group
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Define: dephosphorylation
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remove phosphate group
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What is ATP synthesis?
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(phosphorylation)
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What is ATP hydrolysis?
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(dephosphorylation)
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Chemical energy is stored in _____ bonds.
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Chemical energy is stored in phosphate bonds.
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What is the oxidation-reduction (redox) reaction?
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electron transfer reactions
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What is oxidation?
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loss of electrons
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What is reduction?
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gain of electrons
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Redox reactions are _____ --> one molecule is ____, another is ____.
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Redox reactions are coupled --> one molecule is oxidized, another is reduced.
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Oxygen is the final electron receptor in ____ ____.
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Oxygen is the final electron receptor in cellular respiration.
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Coenzymes act as ____ carriers of H atoms and their electrons.
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Coenzymes act as temporary carriers of H atoms and their electrons.
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Define: energy metabolism
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reactions involved in energy storage and use
-cells use chemical energy to do biological work (transport, movement, etc.) -energy is released when high-energy bonds are converted to lower-energy bonds |
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What is the formula of oxidation of glucose?
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a
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Define: energy
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capacity to perform work
-ATP is the "energy currency" of cells: --energy captured from oxidation of glucose is sued to make ATP (ADP + Pi --> ATP) --energy released from ATP hydrolysis powers energy requiring processes |
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Define: enzymes
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proteins (mostly) that function as catalysts of biochemical reactions
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Define: catalysts
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speed up the rate of chemical reactions in the cell, but are themselves not changed by the chemical reaction
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What are the 5 functional properties of enzymes?
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1. typically proteins (some RNA can also act as enzymes)
2. permit reactions to proceed at conditions body can tolerate at body temperature --> chemical reactions without enzymes are very slow could increase body temperature to speed up reactions but damage cells 3. chemically specific - react only with specific substances substrate binds specifically (lock and key shape) 4. very efficient - can process millions of molecules every second 5. function by lowering the activation energy of reactions |
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What is the energy of activation?
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minimum amount of energy required for a given reaction to occur
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Enzymes are catalysts:
-____ the activation energy of a ____ reaction -enzyme is ____ ____ or ____ ____ in the reaction. |
Enzymes are catalysts:
-lower the activation energy of a chemical reaction -enzyme is not changed or used up in the reaction. |
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Define: substrate
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reactants in enzymatic reactions; bind to active site
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Define: active site
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location on enzyme that fits a particular substrate (lock and key)
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How does an enzyme work?
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aa
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What are the factors affecting rates of enzyme-catalyzed reactions?
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1. enzyme's catalytic rate
2. enzyme concentration 3. temperature and pH 4. substrate concentration 5. affinity of enzyme for substrate |
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What is a catalytic rate?
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number of product molecules produced per unit by an enzyme
**assuming active site is always occupied by substrate |
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What is an enzyme concentration?
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increase enzyme concentration = increased reaction rate
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What is the temperature and pH?
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enzymes have an optimum pH and temperature at which they work the fastest
pH -many proteins function best at pH=7.0 -pH affects charge of amino acids at active site --properties of active site change --> substrate can't bind temperature -most mammalian enzymes work best ~ 40 degrees Celcius -up to optimum temperature - enzyme reaction rate increased with temperature --rate increase because enzyme and substrate have more kinetic energy (so collide more often) -above optimum temperature - rate decrease as enzymes denature --heat breaks hydrogen bonds holding secondary and tertiary structure of enzymes |
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How does a substrate concentration affect the rate of an enzyme-catalyzed reactions?
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increased enzyme concentration = increased reaction rate until...
Every active site on every enzyme - occupied (100% saturation) |
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How does the affinity of enzyme for substrate affect rates of enzyme-catalyzed reactions?
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measure the strength of binding between substrate and enzyme
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Define: allosteric regulation
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activation or inhibition by binding of a modulator to a regulatory site on enzyme
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Define: covalent regulation
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activation via phosphorylation of enzyme, catalyzed by a protein kinase
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Define: feedback inhibition
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product in a reaction sequence binds to enzyme to inhibit earlier step, regulated formation of products
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An allosteric regulation has ___ binding sites. name them
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2 binding sites the active site and regulatory site
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The ___ molecule binds to a regulatory site
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The modulator molecule binds to a regulatory site.
-changes shape/activity of enzyme -can increase or decrease activity Generally alters the affinity or catalytic rate of enzyme |
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In a covalent regulation, an enzyme exists in ___ states. What are they?
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In a covalent regulation, an enzyme exists in two states. What are they? active and inactive
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In a covalent regulation, changing state requires formation of a covalent bond between _____ and _____.
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In a covalent regulation, changing state requires formation of a covalent bond between protein (enzyme) and chemical group (e.g. phosphate group).
-formation/breaking of covalent bond requires enzymes |
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What occurs during feedback regulation?
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a product in a reaction sequence binds to enzyme to inhibit enzyme in an earlier step --> regulates formation of products
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What are the two ways to break food monomers into energy?
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cellular respiration and fermentation
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What is cellular respiration?
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(aerobic respiration) - oxygen is present
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What is fermentation?
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(anaerobic respiration) - no oxygen
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What are the 3 steps of cellular respiration?
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glycolysis, Kreb's cycle, and electron transport chain
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Where does glycolysis take place in?
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the cytosol
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Where does the Kreb's cycle take place?
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mitochondrial matrix
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Where does the electron transport chain take place?
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inner mitochondrial membrane
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If O2 is present in the Krebs cycle it is _____ respiration
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If O2 is present in the Krebs cycle it is aerobic respiration
-can yield up to 38 ATP per glucose and the end products are CO2 + H2O |
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If O2 is not present it is considered _____ respiration.
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If O2 is not present it is considered anaerobic respiration.
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if it is aNaerobic it is oxygen is NOT present.
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1 pyruvate in the Krebs cycle produces
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3 NADH, 1 FADH2, 1 ATP, 2 CO2
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What is the electron transport chain?
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system of electron carrier proteins located in inner membrane of mitochondria
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For each glucose molecule oxidized into ___ and ___: can produce net gain of ___ ATP
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For each glucose molecule oxidized into CO2 and H2O: can produce net gain of 38 ATP
(however, maximum is usually not reached (i.e. "leaky" membranes, etc) |
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If blood glucose levels are low the body can...
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1. use stored glucose energy (in glycogen storage form)
2. synthesize glucose from non-carbohydrates 3. break down fats and proteins into smaller molecules for energy --smaller molecules --> enter cell respiration pathway --> form ATP |
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Define: glycogen
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storage form of glucose in animals (polysaccharide)
-glycogen is stored in the liver and skeletal muscle |
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Define: glycogenesis
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glycogen formation
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Define: glycogenolysis
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glycogen breakdown
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During ____ glucose is not oxidized immediately.
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During glycogenesis glucose is not oxidized immediately.
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During _____ glucose is oxidized immediately.
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During glycogenolysis glucose is oxidized immediately.
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Glycogenesis is stimulated by ____.
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Glycogenesis is stimulated by insulin (secreted from the pancreas).
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Glycogenolysis is stimulated by ___.
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Glycogenolysis is stimulated by glucagon (secreted from pancreas) and epinephrine (adrenal medulla).
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Define: gluconeogenesis
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formation of new glucose molecules from non-carbohydrate precursors (e.g. amino acids, lactic acid)
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Where does gluconeogenesis occurs?
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liver
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Why is gluconeogenesis important?
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during glucose depletion.fasting (e.g. exercise, stress, low carb diet)
-stimulated by cortisol (secreted by adrenal cortex) -protects body (especially the brain) from damaging effects of hypoglycemia --> ensures ATP synthesis can continue |
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What is lipolysis?
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breakdown (catabolism) of lipids into smaller molecules
-smaller molecules can enter respiration pathway |
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Catabolism of fats involves two separate pathways:
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glycerol pathway and fatty acid pathway
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What is the most abundant lipid in the body?
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triglyceride
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1 glycerol enters _____ pathway
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1 glycerol enters glycerol pathway
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3 fatty acids enter _____ pathway
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3 fatty acids enter fatty acid pathway
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What occurs during the glycerol pathway?
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aa
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What occurs during the fatty acid pathway?
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aa
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What is beta oxidation?
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stepwise breakdown of fatty acids to CO2 to H2O
-occurs in the mitochondrial matrix -fatty acids broken down into 2-carbon units --> more are then converted to acetyl CoA --> enters the Krebs cycle -high ATP yield: > 100 ATP per fatty acid |
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What are ketone bodies?
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strong metabolic acids that disrupt pH balance
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excess fat catabolism = excess _____ --> converted into ______.
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excess fat catabolism = excess acetyl CoA —> converted into ketone bodies. (e.g. fasting, diabetes mellitus, low carb diets)
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Define: lipogenesis
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formation of triglycerides from excess dietary glycerol and fatty acids
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What is lipid storage?
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lipids important as energy reserves
-can provide large amounts of ATP... but slowly -saves space (produces a lot of ATP) —> but hard for water-soluble enzymes to access |
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The body synthesizes 100,000 to 140,000 _____ —> each with different form, function, and structure.
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The body synthesizes 100,000 to 140,000 proteins —> each with different form, function, and structure.
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All proteins are built from ___ amino acids.
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All proteins are built from 20 amino acids.
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Cellular proteins are recycled in _____:
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Cellular proteins are recycled in cytosol:
-peptide bonds are broken -free amino acids are used in new proteins |
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During protein metabolism, if other energy sources are inadequate:
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-mitochondria generate ATP by breaking down amino acids in Krebs cycle
-not all amino acids enter cycle at some point, so ATP benefits vary |
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When glucose and lipid reserves are inadequate, liver cells:
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-can break down internal proteins
-absorb additional amino acids from blood —most amino acids for making ATP come from surplus amino acids in diet |
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Define: proteolysis
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hydrolysis of proteins into amino acids
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Free amino acids can:
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1. be used as fuel to make ATP
2. be converted to other amino acids 3. converted to glucose 4. converted into fat |
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What are the three process that free amino acids can perform?
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deamination, amination, and transamination
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Define: deamination
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removal of an amino group
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Define: amination
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addition of amino group
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Define: transamination
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transfer of amino group from one molecule to another
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Amino acids do not enter the ____ or ____ directly —> they first need to be converted into a ____ —> ____ enters pathway
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Amino acids do not enter the Krebs cycle or glycolysis directly —> they first need to be converted into a keto acid —> keto acid enters pathway
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A keto acid can be converted into:
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-pyruvic acid
-acetyl CoA -Acids of the Krebs cycle |
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Ammonia is ____ to cells.
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Ammonia is toxic to cells
-urea pathway —> liver quickly converts ammonia into less toxic urea and urea is excreted in urine |
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_____ form the most important structural and functional components of cells.
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Proteins form the most important structural and functional components of cells.
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Define: nonessential amino acids
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amino acids by the body on demand
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Define: essential amino acids
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-8 not synthesized
-2 insufficiently synthesized |
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Define: metabolic rate
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sum of all anabolic and catabolic processes in the body
-changes according to activity |
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Define: basal metabolic rate (BMR)
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minimum resting energy expenditure:
-of an awake and alert person -measured under standardized testing conditions —involves monitoring respiratory activity —energy utilization is proportional to oxygen consumption |
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basal metabolic rate estimates rate of ____ use.
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basal metabolic rate estimates rate of energy use.
-energy not captured is released as heat. —serves important homeostatic purpose |
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What is thermoregulation?
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homeostatic mechanisms keep body temperature within limited range
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The body produces heat as a by-product of _____
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The body produces heat as a by-product of metabolism
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