L7 - Harvesting Chemical Energy Flashcards
What are the 4 main steps of cellular respiration
Glycolysis
Pyruvate oxidation
Citric acid cycle
Oxidative Phosphorylation (ETC and Chemiosmosis)
Describe the processes occuring in glycolysis
Glucose, 2 ATP invested to produce 4 ATP, 2 NADH and 2 Pyruvate molecules
Oxygen not required
Where do the steps of cellular respiration occur?
Glycolysis - cytosol
Pyruvate oxidation - matrix
Citric acid cycle - matrix
Oxidative phosphorylation - across inner membrane
Describe the processes occuring in pyruvate oxidation
Produces no ATP, but produces 1 NADH per pyruvate (or 2 per glucose) + 1 CO2
Oxygen is required
What is produced in the citric acid cycle
Per glucose molecule:
2 ATP
6 NADH
2 FADH2
4 CO2
Requires oxygen
How much ATP does each step of cellular respiration produce?
Glycolysis - 2 ATP
Pyruvate oxidation - no ATP
Citric acid cycle - 2 ATP
Oxidative phosphorylation - 26-28 ATP
What is substrate phosphorylation
ATP is generated by transfer of a phosphate group to ADP
Glycolysis and Citric acid cycle make ATP via substrate phosphorylation
What is oxidative phosphorylation
ATP is generated from the oxidation of NADH and FADH2 and the subsequent transfer of electrons and pumping of protons
Describe the processes occuring in the electron transport chain
NADH and FADH2 are oxidised to donate electrons
Electrons transfer from protein to protein along the chain in a series of redox reactions
At each transfer, each electron gives up some energy which enables H+ ions to be pumped into the intermembrane space
Oxygen pulls the electrons down the chain and is the final electron acceptor
Describe the processes occuring in chemiosmosis
The H+ ions in the intermembrane space rush down their concentration gradient through ATP synthase
How does cyanide affect the respiration process
Acts on protein complex iv and prevents the passage of electrons to oxygen so no ATP cannot be produced via chemiosmosis
What is phosphofructokinase
The “gate-keeper” for glycolysis
Catalyses step 3 - where glycolysis becomes irreversible
What is phosphofructokinase inhibited and stimulated by?
Inhibited by citrate and ATP
Stimulated by AMP
What happens when blood glucose level is too high
Beta cells in pancreas islets secrete insulin
Insulin promotes glucose uptake into cells
What happens when blood glucose level is too low
Alpha cells in pacreas islets secrete glucagon
Glucagon stimulates the breakdown of glycogen to increase blood sugar levels
How do body cells respond to insulin
Increased rate of glucose transport into target cells
Increased rate of glucose use and ATP generation
Increases conversion of glucose to glycogen
How do body cells respond to glucagon
Increase breakdown of glycogen to glucose
Increased breakdown of fat to fatty acids
Increased synthesis and release of glucose (in liver)
What happens if you lose the function of insulin
No glucose in cells
No ATP from glucose
No glycogen storage for harder times
What is type 1 diabetes
Where body does not produce insulin as beta cells of pancreas are destroyed
Requires insulin replacement
What is type 2 diabetes
Where body produces insulin but receptors are non functional
What are consequences of diabetes mellitus
Levels of glucose in the blood build up
Subsequently alters the volume and osmorality of blood
Two of the symptoms of diabetes are increased hunger but also weight loss. Why is this?
Insulin is not able to get inside cells to make ATP
So glucose is excreted via urine
What step of respiration does glycerol enter
Glycolysis
What step of respiration do amino acids enter
Glycolysis and citric acid cycle
