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31 Cards in this Set
- Front
- Back
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What type if protein is an enzyme? |
Large globular protein |
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What type of reaction is a anabolic reaction? |
Build up reaction |
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What type of reaction is a catabolic reaction? |
A breaking down reaction |
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Are enzymes soluble or insoluble in water? And why? |
Soluble they have many hydrophilic side groups |
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Do enzyme action occur intracellularly or extracellularly? |
Both |
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What type of reaction do oxidoreductases catalyse? |
Transfer of electrons in oxidation and reduction reactions |
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What type of reactions does transferases catalyse? |
The transfer of a functional group from one molecule to another |
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What type of reaction do hydrolases catalyse? |
The hydrolysis of bonds |
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What type of reaction do lyases catalyse? |
The splitting of bonds other than by hydrolysis or oxidation |
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What type of reaction do isomerases catalyse? |
Isomerisation of molecules |
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What type of reaction do ligases catalyse? |
The joining of two molecules by the formation of covalent bonds |
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How do enzymes increase the rate of reaction? |
Lowers the activation energy by creating a transmission state between the enzyme and the substrate that is more stable |
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Who proposed the lock and key theory and when? |
1894 by Hermann Fischer |
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What does the lock and key theory suggest? |
The active site is very precise and is maintained by the tertiary structure of the enzyme. Only the substrate that complementary fits the enzyme can bind to it |
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What is the term for when a enzyme and substrate bind together? |
Enzyme - substrate complex |
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Is the enzyme used up in the reaction? |
No |
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Who proposed the induced fit theory and when? |
Daniel Koshland in 1958 |
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What does the induced fit theory suggest? |
He proposed that at first the active site is not an excat fit for the substrate molecule but as they move closer together forces between the two molecules distort the active site until it is an excat fit |
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What are activators? |
Inorganic groups that are permanently bound to the enzyme so are a type of prosthetic group |
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What are co-enzymes? |
Organic molecules that only temporarily bind to the enzyme and transfers a chemical group that is necessary for the chemical reaction |
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What are the four factors that can affect enzyme controlled reactions? |
Temperature pH Enzyme Concentration Substrate Concentration |
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What is the equation for the initial rate of reaction? |
Amount of product Time |
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How does temperature affect the rate of reaction at sub - optimum temperatures? |
This increases the rate of reaction because the reactants have more KE so are moving around more and more likely to collide |
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At above optimum temperatures what does an increase on temperature do? |
Decrease the rate of reaction because the bonds that maintain the tertiary structure start to break down and irreversibly change the shape of the active site |
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How does a highly acidic or alkaline environment affect enzymes? |
H+ ions and OH- ions interact with the amino acids within the enzyme breaking the bonds and altering the shape of the active site |
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How does substrate concentration affect the rate of reaction? |
Rate of reaction is directly proportional to substrate concentration until it reaches a maximum value. After a point active site saturation will happen so an increased substrate concentration will have no further affect. |
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How does enzyme concentration affect the rate of reaction? |
Rate of reaction is directly proportional to enzyme concentration up to a certain value. After a certain point all of the substrates will be in use so increasing the enzyme concentration will have no affect |
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What is an inhibitor? |
A substance that interferes with enzyme activity |
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What does a competitive inhibitor do? |
It competes with the substrate for the active site. It binds to the active site to create a enzyme - inhibitor complex which blocks the substrate molecule. |
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What does an non - competitive inhibitor do? |
These don't compete with the substrate or bind to the active site. It instead binds with the allosteric part of the enzyme for here it distorts the active site so the substrate can't bind with the active site because it doesn't fit. |
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What is the difference between reversible and irreversible inhibitors? |
Reversible inhibitors only bind to the enzyme by relatively weak bonds (hydrogen bonds). The inhibitor is able to leave the enzyme and allows the substrate to bind as normal. Irreversible inhibitors permanently bind to the enzyme so fully block the substrate from binding to it |
