1.4 Enzymes Flashcards
1
Q
Define metabolism
A
- all the organisms chemical processes, comprising anabolic and catabolic pathways
2
Q
What is a metabolic pathway
A
A sequence of enzyme controlled reactions in which a product of one reaction is a reactant in the next
3
Q
Define an enzyme
A
- biological catalyst
- globular protein made by cells that alters the rate of a chemical reaction without being used up itself
4
Q
What structure are enzymes in?
A
Tertiary (globular)
5
Q
Are enzymes soluble or insoluble?
A
- soluble as R groups of enzymes are hydrophilic
- active site is insoluble due to hydrophobic R groups
6
Q
Extracellular enzymes
A
- secreted (exocytosis) from cell for outside action
- eg amylase made in salivary glands moves down duct ti the mouth
7
Q
Intracellular (solution) enzymes
A
- act inside solution in cells ie cytoplasm
- eg enzymes that catalyse glycolysis (respiration stage in cytoplasm) or enzymes in stroma of plants that catalyse photosynthesis
8
Q
Intracellular (membrane bound) enzymes
A
- attached to membranes
- eg cristae of mitochondria for ATP formation
9
Q
What is the enzyme for hydrogen peroxide break down?
A
- catalase
- hydrogen peroxide damages dna in cell if not broken down
10
Q
Explain the lock and key model
A
- enzyme and the active site are perfectly complimentary so each enzyme only catalyses one type of reaction
- active site does not change
- able to synthesise and split molecules
- temporary bonds form enzyme substrate complex
11
Q
Explain the induced fit model
A
- active site flexible - alters slightly to accommodate substrate
- ie lysozyme in mucus and tears - groove molds to substrate
12
Q
Define activation energy
A
- minimum energy that must be put into a chemical system for a reaction to occur
13
Q
How do enzymes speed up chemical reactions?
A
- lower activation energy
- reactions can take place at lower temp
- modify substrate
14
Q
How does temperature influence rate of reaction?
A
- increases as temp increases as more KE so greater rate of successful collision (therefore more enzyme-substrate complexes)
- rate falls after optimism as the enzyme/active site denatures
- optimum temp in mammals is 37.5
15
Q
How does pH influence rate of reaction?
A
- anywhere away from optimum pH decreases the rate
- alters some of the charges in the active site which disrupts H bonds in tertiary structure - reversible but can become permanent
- extreme changes result in key bonds in tertiary breaking, altering the AS shape and therefore denatured enzyme