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Why are enzymes complex?
- Very Specific
- Speed up reaction by factor of millions
- Reduce energy of activation
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What is the Transition State?
A state of high energy level in reaction leading to product formation.
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Will an enzyme work outside of it normal temperature or pH range? Why?
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What is the equation for equilibrium constant?
Keq = KF[A]n/KR[B]m = [B]m/[A]n
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What happens at the active site of an enzyme?
Holoenzyme - Subrate banding and catalytic activity
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What are the two parts of an enzyme?
- Protein- apoenzyme
- Non-protein - cofactor
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What is the lock and key model of an enzyme?
- Enzyme- lock
- Substrate- key
- Doesn't take into account protein conformations.
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What is the induced-fit model of action enzyme?
Assumes enzyme conformation changes to accommodate the substrate molecule
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How are enzymes classified?
According to the type of chemical reaction is catalyzes.
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What are the six enzyme categories?
- Oxidoreductases
- Transferases
- Hydrolases
- Lyases
- Isomerases
- Ligases
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What is kinetics?
The rate (velocity) and mechanism of a reaction
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How are rates usually measured?
How many moles of reactant or product are changed per time period.
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What is a mechanism?
A detailed step by step description of how a reaction occurs at the molecular level.
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How are all rate equations determined?
Experimentally
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When the addition of more reactant has no effect on the rate what is it called?
Zero Order
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What is a competitive inhibitor?
Looks like the substrate and binds to enzyme at active site
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What is an uncompetative inhibitor?
Binds only to the enzyme-substrate complex
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What is a noncompetitive inhibitor?
- Doesn't look like the substrate
- Doesn't bind at the active site
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What do allosteric enzymes show?
Cooperative binding
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Why are transition metals useful as catalysis?
- High positive charge
- Accepts electrons (Lewis acid)
- Mediate redox reaction
- Polarize water molecules
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Coenzymes are organic molecules often derived from what?
Vitamins
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What is the mechanism for Chymtrypsin?
Catalyzes the hydrolysis of peptide bonds next to aromatic side chains.
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What are some methods that organisms use to regulate enzyme activity?
- Genetic control
- Covalent Modification
- Allosteric Regulation
- Compartmentation
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What is an example of enzyme induction?
- E. coli is induced to use lactose in the absence of glucose.
- Turned on by genetic control
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When the product of a biochemical pathway inhibits the functioning of a key enzyme of a previous step in the pathway it is called _______ _______?
Enzyme repression
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What are the two allosteric models?
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What does the term carbohydrate mean?
- Compounds associated with polyhydroxy
- aldehydes -aldo
- ketones -keto
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What are the names for monosaccarides with 3, 4, 5, and 6 carbons?
- 3 - triose
- 4 - tetrose
- 5 - pentose
- 6 - hexose
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What are enantiomers?
Non-superimposable mirror image molecules
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Where are most of the oxidized carbon in a Fischer projection?
At the top
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What are anomers?
The alpha and beta forms of cyclic sugars
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What is cellulose?
The major structural polymer in plants
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What are starches?
Storage forms of glucose in plants
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What is glycogen?
The storage carbohydrate in animals (liver and muscle cells)
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What is chitin?
Provides structural support for exoskeleton in invertebrates.
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What is a glycoconjugate?
Compounds that convalently link carbs to proteins and lipids
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What is glycolysis?
Break down of an organic molecule (sugar) to make energy
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What is the net ATP formed from glycolysis?
2
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What is pyruvate?
a 3 carbon molecule
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What is gluconeogenesis?
Making glucose from noncarbohydrate sources. ( 3 irreversible steps of glycolysis are bypassed)
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What is is called when lactate from the skeletal muscle is transferred to the liver where it is converted to pyruvate then glucose?
Cori Cycle
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What is is called when pyruvate in the muscles is converted to alanine which is transported to the liven and reconverted to pyruvate?
Alanine cycle
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What happens in the pentose phosphate pathway?
- Five Carbon Sugars are produced
- NADPH is produced for biosynthesis
- Reshuffling of carbons to give products with 3,4, 6,7 carbons
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If NADPH is need, what steps must occur?
Oxidative
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What reacts via the pentose phosphate pathway t make ribose?
Fructose and glyceraldhyde
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What removes glucose units until 4 are left approaching a branch point?
Glycogen phosphorylase
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What is central to the control of glycogen metabolism and is overall an important means of enzyme regulation?
Covalent modification
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