Chapter 3 Flashcards
(23 cards)
What is the first law of thermodynamics?
the law of conservation of energy, energy can neither be created nor destroyed.
What is transduction?
conversion of energy from one form to another.
What is the second law of thermodynamics?
events in the universe tend to proceed from a state of higher energy to a state of lower energy.
What is entropy?
Measure of randomness or disorder
What is the energy available to do work?
Free energy, delta G
What are cofactors>?
inorganic enzyme conjugates
What are coenzymes?
organic enzyme conjugates
What are the properties of enzymes?
1) Are present in cells in small amounts
2) Are not permanently altered during the course of a reaction
3) Cannot affect the thermodynamics of reactions, only the rates
4) Are highly specific for their particular reactants called substrates.
5) Produce only appropriate metabolic products
6) Can be regulated to meet the needs of a cell
What are some mechanisms of enzyme catalysis?
1) Substrate orientation
2) Changing substrate reactivity
3) Inducing strain in the substrate
What do irreversible inhibitors do?
Bind tightly to the enzyme
What do reversible inhibitors do?
bind loosely to the enzyme
Competitive inhibitors:
- Compete with the enzyme for active sites
- Usually resemble the substrate in structure
- Can be overcome with high substrate/inhibitor ratios
Noncompetitive inhibitors:
Bind to other sites other than active sites and inactivate the enzyme.
* Cannot be overcome with high substrate/inhibitor ratios
Catabolic pathways:
Break down complex substrates into simple end products.
- Provide raw materials for the cell.
- provide chemical energy for the cell
Anabolic pathways:
Synthesize complex end products from simple substrates
- Require energy
- Use ATP and NADPH from catabolic pathways.
What enzyme is needed for conversion of Glucose-> glucose 6-phosphate?
Hexokinase
What enzyme is needed for conversion of glucose 6-phosphate–> fructose 6-phosphate?
phosphoglucose isomerase
What enzyme is needed for conversion of fructose 6-phosphate–> fructose 1,6-biphosphate?
phosphofructokinase
What enzyme oxidizes and reduced cofactors?
Dehydrogenase
When is NAD+ reduced?
when glyceraldehyde 3-phosphate is converted to 1,3- biphosphoglycerate
When is ATP formed?
when 1,3-biphosphoglycerate is converted to 3-phosphoglycerate by 3-phosphoglycerate kinase.
What enzymes transfer phosphate groups?
Kinase
What occurs when ATP is formed by a kinase enzyme?
substrate-level phosphorylation
