8 Metabolism (HL) Flashcards
How do enzymes increase the rate of biochemical reaction?
Decreasing activation energy
Define exergonic reaction
Energy is released
Usually catabolic
Define endergonic reaction
Energy is absorbed
Usually anabolic
What are the two types of enzyme inhibition?
Competitive and non competitive
Describe competitive inhibition
Inhibitor is structurally similar to the substrate and directly binds to the active site
What occurs to the effects of the competitive inhibitor if substrate concentration increases?
Effects decrease
Describe non-competitive inhibition
Inhibitor binds to an allosteric site and changes the active site shape so the substrate can no longer bind
What occurs to the effects of the non-competitive inhibitor if substrate concentration increases?
No change
Give an example of a competitive inhibitor
Relenza
Drug which fights influenza by competitively inhibits the enzymes which triggers the release of virions from the infected cell
Give an example of a non-competitive inhibitor
Cyanide
Binds to the allosteric site on cytochrome oxidase (carrier molecule in the ETC of respiration)
Therefore ATP is not produced
Describe end-product inhibition
Final product inhibits an earlier step via non-competitive inhibition (temporarily inactivates the enzyme)
Which two sources can synthesise ATP from ADP?
Solar energy
Oxidative processes
What is the first step in the breakdown of carbohydrates?
Glycolysis
Where does glycolysis occur?
Cytosol
What happens in glycolysis?
Hexose (6C) -> Pyruvate (3C)
What are the 4 steps of glycolysis?
Phosphorylation
- 2ATPs phosphorylate the hexose making it more unstable
Lysis
- 6C sugar breaks into 2 triosephosphates (3C)
Oxidation
- H atoms are removed from each 3C (NAD+->NADH + H+) (2x NADH in total)
ATP formation
- 2 ATP molecules are synthesised per 3C molecule to produce pyruvate (4x ATP in total)
What is the net gain of H carrying molecules and ATP in glycolysis per hexose?
2 ATP (4 produced, 2 used)
2 (NADH + H+)
What happens after glycolysis in the absence of oxygen?
The pyruvate is converted to lactic acid
What happens after glycolysis in the presence of oxygen?
The pyruvate is transported to mitochondria for further breakdown
What is the second step of respiration (1st step unique to aerobic respiration)?
Links reaction
Where does the links reaction occur?
The pyruvate is transported into the mitochondrial matrix at the start of the reaction
What occurs to each pyruvate in the links reaction?
Decarboxylation (loss of a CO2)
Loss of 2H for NAD+ -> NADH + H+ creates a 2C which forms an acetyl group
Coenzyme A bonds to the acetyl group -> Acetyl CoA
What is the net gain of H carrying molecules and ATP in the links reaction per hexose?
2 (NADH + H+)
(as well as 2CO2)
1 of each per pyruvate