energy I Flashcards
1
Q
catabolism
A
Breakdown of complex molecules to release energy or carry out mechanical work
2
Q
anabolism
A
Synthesis of new molecules from less complex components
3
Q
Energy provision
A
ATP is central to a cell and therefore the body’s energy provision
Can act as both an acceptor and donator of energy Acts as a short term reservoir of energy Body only has 100g of ATP therefore ATP is resynthesized from ADP
4
Q
Glycolysis
A
6C glucose molecules very unstable, therefore metabolized into 2 3C molecules
The glucose is phosphorylated to glucose 6 phosphate Fructose 6 phosphate is phosphorylated into fructose 1,6 biphosphate This is an unstable compound therefore metabolises into 2 3C molecules One is glyceraldehyde 3 phosphate and the other is Dihydroxyacetone phosphate Phosphoenol pyruvate is formed which is converted into phenol by losing a phosphate and phosphorylating ADP 2 ATP and one NADH also formed Net gain of 2 ATP as there are 2 3C molecules which undergo the second step
5
Q
Regulation of glycolysis
A
Potential sites for regulations are enzymes which catalyse irreversible reactions
Regulated by: Reversible binding of allosteric effectors Covalent modification Transcription Hexokinase catalyses the phosphorylation of hexose sugars and is regulated by G6P Phosphofructokinase converts fructose-6-phosphate to fructose-1,6-biphosphate and is regulated by ATP, citrate from TCA cycle, H+ ions and AMP Pyruvate kinase catalyses the phosphorylation of ADP by transferring the phosphate from phosphoenol pyruvate and is inhibited by high levels of ATP
6
Q
AMP
A
Stimulates PFK and is generated by the hydrolysis of ADP
High concentration of ATP and low pH inhibits PFK Lowers affinity for fructose 6 phosphate Inhibition of PFK leads to inhibition of hexokinase
7
Q
Regulation of glycolysis in the liver
A
High concentration of ATP inhibits PFK
PFK is inhibited by citrate PFK is stimulated indirectly by a build up of F6P Hexokinase inhibited by G6P but not glucokinase Glucokinase has a high Kt Only active when glucose concentration are high Allows liver to regulate blood glucose
8
Q
Exercising tissue and tumours
A
Energy needs met through aerobic respiration
Pyruvate is reduced resulting in the oxidation of NADH to form NAD and the formation of lactate NAD required for anaerobic respiration Lactate is acidic and inhibits glycolysis therefore broken down in liver
9
Q
Tumours
A
Inappropriate growth
Recruits blood vessels as it grows Tumours can outgrow their blood supply reducing the oxygen delivery Therefore tumour cells revert to glycolysis Reduction in O2 leads to the activation of the transcription of HIF-1α HIF-1α regulates the expression of a number of enzymes in the glycolytic pathway
