Energy 1: Metabolism, ATP, Glycolysis Flashcards
What is metabolism?
The use of energy to: Synthesise new molecules Establish ion gradients Perform mechanical work Keep warm
What are catabolic processes?
The breakdown of complex molecules to release energy
What are anabolic processes?
Synthesis of new molecules from less complexes components
When is ATP production mainly done?
When nutrients are oxidised
By which processes is ATP broken down?
Biosynthesis, detoxification, contraction, ion transport, thermogenesis
How much ATP is available from the hydrolysis of ATP?
65 Kj/Mol
How much ATP do we use at rest?
40Kg/24 Hr
How much ATP do we use during exercise?
0.5 Kg/min
What’s the total body content of ATP?
100g
What do the cofactors NAD and FAD do?
Activated carriers of electrons used for oxidation or reduction reactions?
What does NAD stand for?
Nicotinamide adenine dinucleotide
What does FAD stand for?
Flavin adenine dinucleotide
What are the oxidised and reduced forms of NAD?
Oxidised= NAD+ Reduced= NADH+
What are the oxidised and reduced forms of FAD?
Oxidised= FAD+ Reduced= FADH2
What is glycolysis?
The splitting of a glucose (C6) molecule into two pyruvate (C3) molecules
What are the two functions of the formation of glucose 6- phosphate?
- maintains the glucose gradient
- traps the glucose within the cell (which is largely irreversible)
What are the reactants in glycolysis?
1 glucose 2 ATP 2NAD+ 2 ADP 2Pi
What are the products of glycolysis?
2 pyruvate
2 NADH
2 ATP
How is there a net gain of 2 ATP and 2 NADH in glycolysis?
The second step happens twice ( as 2x C3 molecules)
What regulates glycolysis?
- enzyme catalysing irreversible reactions that are potential sites for regulation
- enzyme regulation
How can activity of enzymes be regulated?
- reversible binding of allosteric effectors
- covalent modification
- transcription
What does hexokinase do?
Regulates glucose -> G6P
What does phosphofructokinase do?
Fructose 6 phosphate ->Fructose 1,6 bisphosphate
In which tissue does pyruvate kinase have more points for allosteric regulation?
Liver
What tissues don’t have the pyruvate kinase allosteric regulation sites?
Heart, brain, and skeletal system
What happens in tissues that don’t have the pyruvate kinase allosteric regulation sites?
They aren’t regulated at the level of pyruvate kinase?
What does pyruvate kinase do?
Phosphoenol pyruvate-> pyruvate
How is hexokinase regulated?
Inhibited by G6P so prevents too much glucose being fed down the glycolytic pathway
How is phosphofructokinase regulated?
Inhibited by ATP, citrate and H+
Positively regulated by AMP
What is AMP a good indicator of?
The energetic state of the cell
Why is phosphofructokinase inhibited by ATP?
No need for glycolysis if ATP is present within the cell
Why is phosphofructokinase inhibited by citrate?
Leads onto the TCA cycle which produces ATP
Why is phosphofructokinase inhibited by H+?
Prevents the skeletal muscle being damaged by the low pH of continued glycolysis
What is pyruvate kinase inhibited by?
ATP
When is AMP produced?
When there is significant amounts of ADP
When is ADP elevated
When the consumption of ATP is high and synthesis of ATP is required
What enzyme makes AMP?
Adenylate kinase
What is the reaction that has ATP, ADP and AMP?
2ADP => ATP +AMP
How does high ATP concs inhibit phosphofructokinase (PFK)?
Lowers the affinity for fructose 6 phosphate
What does inhibition of PFK lead to?
Hexokinase as a reduction of PFK use leads to an increase of G6P and therefore an inhibition of hexokinase
What is PFK inhibited by?
High ATP conc and citrate
What is PFK stimulated by?
Indirectly by a F6P build up
What is hexokinase inhibited by?
G6P
What molecules mean that other molecules can join the glycolytic pathway?
Fructose (adipose)-> F6P
Fructose (liver)->DMAP
Fructose (liver)->GAP
How can glycolysis be inhibited?
The amount of NAD in the cell
How do muscles overcome the lack of NAD+?
Synthesis of lactic acid lactate from pyruvate
What are the limitations of using lactic acid as a source of glucose?
Lactic acid is acidic so will lead to a reduction in pH which has an inhibiting effect on PFK
What happens to the pyruvate in an aerobic state?
Converted to acetyl coenzyme A which then leads to the process of oxidative phosphorylation
What happens to the vascular system when a tumour grows?
As size increases, the need for blood grows. Angiogenic factors are released which ultimately leads to the formation of a vascular network
What is an angiogenic factor?
Stimulate the endothelial cells of a nearby vessel to proliferate and migrate
Why are tumours kept in an anaerobic state?
The rate at which the tumour grows is faster than the vessels are able to deliver oxygen
What stimulates the expression of many glycolytic enzymes?
Low oxygen
What happens in hypoxia?
HIF1 activated which stimulates blood vessel growth and metabolic adaptation
