Energy I Flashcards
What is Catabolism?
Breakdown of complex molecules to release energy or carry out mechanical work
What is Anabolism?
Synthesis of new molecules from less complex components
How much ATP does the body contain and what does that mean?
Body only has 100g of ATP therefore ATP is resynthesized from ADP
What is glucose metabolised into and why?
6C glucose molecule very unstable, therefore metabolised into 2 3C molecules
What is the process where glucose is phosphorylated ?
○ 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
In glycolysis What is formed and what is it converted into?
Phosphoenol pyruvate is formed which is converted into phenol by loosing a phosphate and phosphorylating ADP.
What else is formed in glycolysis?
2 ATP and 1 NADH formed
What is the net gain in glycolysis?
Net gain of 2 ATP as there are 2 3C molecules which undergo the second step.
What is glycolysis regulated by?
• Regulated by:
○ Reversible binding of allosteric effectors
○ Covalent modification
Transcription
What does hexokinase do and what is it regulated by?
Hexokinase catalyses the phosphorylation of hexose sugars and is regulated by G6P
What does phosphofructokinase do and what is it regulated by?
Phosphofructokinase converts fructose-6-phosphate to fructose-1,6-biphosphate and is regulated by ATP, citrate from TCA cycle, H+ ions and AMP
What does pyruvate kinase do?
Pyruvate Kinase catalyses the phosphorylation of ADP by transferring the phosphate from phosphoenol pyruvate and is inhibited by high levels of ATP
What does AMP stimulate?
Stimulates PFK
How is AMP generated?
Hydrolysis of ADP
What conditions inhibit PFK and why?
• High concentration of ATP and low pH inhibits PFK
Lowers affinity for Fructose 6 Phosphate
What does the inhibition of PFK lead to?
Inhibition of PFK leads to inhibition of hexokinase
What does a high concentration of ATP do?
High concentration of ATP inhibits PFK
What does citrate inhibit?
PFK
What is PFK indirectly stimulated by?
PFK is stimulated indirectly by a build up of F6P
What is hexokinase inhibited by?
Hexokinase inhibited by G6P but not glucokinase
Does glucokinase have a high Kt?
○ Glucokinase has a high Kt
§ Only active when glucose concentration are high
Allows liver to regulate blood glucose
How are the energy needs for Exercising tissue and tumours met?
Energy needs met through anaerobic respiration
What is reduced in anaerobic respiration and what does this result in exercising tissue and tumours?
Pyruvate is reduced resulting in the oxidation of NADH to form NAD and the formation of lactate
What is required for anaerobic respiration?
NAD required for anaerobic respiration
What is lactate and what does it inhibit?
Lactate is acidic and inhibits glycolysis therefore broken down in liver
What type of growth is tumours?
Inappropriate growth
What do tumours recruit?
Recruits blood vessels as it grows
What can tumours outgrow and the consequence?
• Tumours can outgrow their blood supply reducing the oxygen delivery
Therefore tumour cells revert to glycolysis
What does the reduction in O2 lead to in tumours?
Reduction in O2 leads to the activation of the transcription of HIF-1α
What does HIF-1a regulate?
HIF-1α regulates the expression of a number of enzymes in the glycolytic pathway
