Term
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Definition
catalysts that increase the rate of all chemical reactions in cells
1. increase rate of chemical reactions without the enzyme being used up or altered
2. increase reaction without altering chemical equilibrium |
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Term
Describe substrates and products relating to enzymes
1. Transition state
2. Activation energy
3. ES |
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Definition
S is converted to P
-equilibrium determined by thermodynamics (final energy states)
1. substrate must be converted to higher energy state
2. energy required to get to transition state
-stabilize trans state to lower Ea
-doesn't change delta G (products-reactants)
3. enzyme substrate complex
-sub binds to active site on enzyme |
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Term
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Definition
binding is very specific interaction
-active sites are clefts or grooves on surface
-formed by tertiary structure
Substrates bind to active site by hydrogen bonds, ionic bonds, hydrophobic interactions |
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Term
| Describe the two models for ES interaction |
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Definition
1. Lock and key
-substrate fits right into active site
2. Induced fit
-configurations of both the enzyme and substrate are modified
*marriage |
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Term
| Describe enzyme in the catalytic process |
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Definition
-side chains (acidic or basic) in the active site react with substrate and form bonds with intermediates
ex. Chymotrypsin digests by catalyzing hydrolysis of peptide bonds |
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Term
| Describe Prosthetic groups |
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Definition
small molecules bound to enzymes that assist in catalytic process
ex. heme in hemoglobin carries 02
*usually metal ions (Zn or Fe) |
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Term
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Definition
low molecular weight organic molecules that enhance reaction rates
-not altered by reaction
-recycled
-related to vitamins
ex. NAD+ accepts electrons in oxidation rxns
NADH takes electrons (catabolic)
NADPH (anabolic) |
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Term
Describe enzyme regulation
1. feedback inhibition
2. allosteric regulation
3. phosphorylation |
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Definition
1. product of metabolic pathway inhibits enzyme at start or at branch
ex. excess isoleucine stops threonine deaminase
2. binding of small molecules to non active site and changes conformation of enzyme and alters active site
3. addition of phosphate that stimulates or inhibits activity of enzymes
-changes conformation
ex. glycogen phosphorylase is activated when phosphate is added by phosphorylase kinase
-can convert glycogen to glucose |
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Term
Describe Metabolic Energy
1. Gibbs free energy
2. Equation |
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Definition
1. depends on heat released and entropy
-if negative, spontaneous (heat given off, increase in entropy)
-if positive, must be coupled with another reaction
2. G=-RT lnK (B/A)
-products over reactants |
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Term
| Describe the function of ATP |
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Definition
stores free energy in the high energy phosphate bond P-P-P
-hydrolysis=release of free energy
G=-12kcal/mol of ATP in the cell
-can be converted to AMP which is twice the energy
-ATP hydrolysis is coupled with energy yielding rxns |
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Term
| Describe the energy released from complete breakdown of glucose |
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Definition
complete breakdown gives G=-686kcal/mol
-not productive and can't be controlled to extract energy
-must be controlled with enzymes to produce ATP to store energy
Glycolysis= 4 ATP- 2 ATP= 2 net ATP
-also use 2 NAD+ -> 2 NADH
Krebs Cycle= 2 ATP (GTP)
-8 NADH (3 ATP each)
-2 FADH2 (2 ATP each)
Electron transport chain
10 NADHx3 ATP= 30
2 FADH2x2 ATP= 4
Substrate from glycolysis= 2 net
Substrate from Krebs= 2
Total=38 but sometimes 36 |
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Term
Describe the importance of these enzymes
1. Hexokinase
2. PFK
3. Phosphoglycerate kinase |
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Definition
1. uses up one ATP to add phosphate to glucose
2. uses up one ATP to add phosphate to fructose
*acts as critical regulatory feedback inhibitor when excess ATP binds
3. adds phosphate to ADP making ATP
-high energy P from 1,3 bisphosglys breaks off and binds to ADP |
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Term
Describe the recycling of NADH
1. Aerobic
2. Anaerobic |
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Definition
1. reoxidized to NAD+ by conversion of pyruvate to lactate
-ethanol in yeast
-lactic acid lowers pH which alters hemoglobin to release more O2
2. NADH donate electrons in electron transport chain |
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Term
| Describe where glycolysis takes place |
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Definition
Cytosol
pyruvate is taken to mitochondria and oxidized |
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Term
| Describe the oxidation of pyruvate |
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Definition
pyruvate + CoA-SH + NAD+ --> CO2 + AcetylCoA + NADH
AcetylCoA enters Krebs cycle
-combines with oxaloacetate to yield citrate
-releases 2 CO2 and recycles as oxaloacetate |
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Term
Describe in brief oxidative phosphorylation
1. electron transfer
2. end result |
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Definition
1. NADH and FADH2 transfer electrons to 02 which releases free energy to drive synthesis of ATP
-for NADH delta G=-52.5kcal/mol
2. NADH= 3 ATP
FADH2= 2 ATP each |
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Term
Describe the breakdown of organic molecules into energy
1. sugars
2. nucleotides
3. amino acids
4. lipids |
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Definition
1. glycolysis
2. broken down into sugars
3. degraded via Krebs cycle
4. glycerol and free FA
-FA forms with CoA to make FA-CoA
-broken down 2 carbons at a time
-net gain is 130 ATPs per 16 carbon FA
-2.5 times greater than sugars |
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Term
Describe photosynthesis
1. equation
2. light reactions
3. dark reactions |
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Definition
1. 6 CO2+6 H20 -> C6H12O2 + 6 O2
2. sunlight drives ATP and NADPH synthesis
-coupled with oxidation of H20 to O2 from sunlight energy
-high energy electrons enter electron transport chain
3. ATP and NADPH from light reactions drive synthesis of carbohydrates from CO2
-one molecule of CO2 at a time is added to Calvin Cycle |
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Term
| Describe the Calvin Cycle |
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Definition
-uses CO2 to create carbohydrates
-consumes 18 ATP and 12 NADPH for each glucose
-two electrons needed to convert NADPH |
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Term
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Definition
-in animals starts with lactate, amino acids, glycerol
-pyruvate is converted to glucose |
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Term
| Describe the synthesis of glycogen/starch |
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Definition
-dehydration reaction that brings two glucose molecules together must be coupled with energy yielding reaction
-ATP then UTP making UDP glucose |
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