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Index
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Biology U3 - Enzymes
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Chapter 1
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Level 1
level: Level 1
Questions and Answers List
level questions: Level 1
Question
Answer
Are changed and a new coenzyme must be used for every new reaction.
Coenzymes after a reaction
Globular proteins that lower the activation energy for (catalyse) certain chemical reactions.
Enzymes
Substrate specific (folded to have a complementary active site where the substrate binds); can be used again and again; aren't reactants nor products; work best at optimal temperatures & pH levels
Enzyme properties
When an enzyme loses its powers/shape from a temperature too far past the optimal point, or a pH too far from the optimum.
Denaturation
Cool temperatures as there is less kinetic energy for particles to move.
Low enzyme activity cause
When substrates bind to an enzyme the shape is changed slightly to enhance efficiency (of to inhibit if it is a competitive inhibitor)
Induced fit theory
1. R-groups lining active site molecularly interact with the substrates'. 2. substrates bonds weakened. 3. substrates broken or rearranged to form products. 4. products released and enzyme can be used again.
Enzyme cycle
Increase in enzyme concentration; optimal temperature; optimal pH; increase in substrate concentration; decrease in inhibitor concentration
Increase in enzyme activity causes
Small molecule (not a protein) essential for the activity of some enzymes and chemical processes - they assist catalysis by binding to enzymes or carrying electrons/protons or atoms like phosphate (type of cofactor)
Coenzyme
Inorganic metallic ions that bind to an enzyme to increase catalysis rate (a type of cofactor)
Metal cations
A reaction that releases energy (exergonic). E.g. hydrolysis - ATP becomes ADP.
Catabolic reaction
A reaction that requires energy (endergonic). E.g. phosphorylation - ADP becomes ATP.
Anabolic reaction
Inhibitors that permanently bind to an enzyme's active site. Toxic to cells (e.g. nerve gases, toxins)
Irreversible inhibitors
An inhibitor prevents an enzyme from functioning as usual by binding to its active site, preventing a substrate from binding.
Competitive inhibition
An inhibitor prevents an enzyme from functioning as usual by binding to an allosteric site, preventing a substrate from binding by changing the shape of the active site.
Non-competitive inhibition
All active sites are constantly occupied, and some other factor is limiting rate of enzyme activity.
Saturation point
Are changed and a new coenzyme must be used for every new reaction.
Coenzymes after a reaction