Energy Metabolism Flashcards
What are the monomers of Protein?
Amino Acids
What are the monomers of Carbohydrates?
Monosaccharides
What are the two components of Fats?
Fatty Acids and Gycerol
What are amino acids, monosaccarides and fatty acids converted to before entering the citric acid cycle?
Acetyl CoA
What is cellular respiration involve?
The oxidation of food monomers (removal of H+ ions to obtain ATP, CO2 and water)
Which two vitamins assist the dehydrogenase enzymes in the oxidation?
Vitamin B2 and Vitamin B3
What is the net gain of ATP from anaerobic metabolism of glucose?
2 ATP
What is the net gain of ATP from aerobic metabolism of glucose?
32 ATP
List the 4 main steps of aerobic metabolism of glucose
1) Glycolysis: glucose → 2 pyruvate in 8 sub steps
2) Pyruvate → Acetyl CoA (by pyruvate dehydrogenase)
3) Acetyl CoA → Citric Acid Cycle in 8 steps producing NADH+, H+, FADH2 and CO2
4) Electric Transport Chain: electrons travel down their concentration gradients in inter-membranous space using ATP synthase
Where in the cell does anaerobic metabolism of glucose occur?
The cytosol
Which enzyme converts pyruvate to Acetyl CoA?
Pyruvate dehydrogenase
What does Acetyl CoA combine with when it enters the citric acid cycle and what does it form
It combines with Oxaloacetate to form Citrate
Briefly describe oxidative phosphorylation
H+ ions are pumps into the intramembranous space and flow down their concentration gradient along electron carrier proteins
Energy from this is transferred to bind ADP + Pi to reform ATP using the enzyme complex ATP Synthase
How do RBC’s metabolism glucose
Red Blood Cells can do not have a mitochondria so can only metabolise glucose anaerobically
What occurs in cells when oxygen is not present?
Pyruvate is converted to lactate instead of Acetyl CoA
Explain the Cori Cycle
The Cori Cycle allows the lactate produced in the muscles to move into the liver where it can be reconverted to glucose which is then released into the blood stream
What is Lipolysis?
Triglycerides → free fatty acids + glycerol
What is Beta Oxidation?
The oxidation of fatty acids in which 2 carbons are cleaved off the beta end, forming Acetyl CoA
How many ATP can be generated from one fatty acid?
1 fatty acid = 16 carbons = 106 ATP
What is Ketogenesis?
When Acetyl CoA is converted to ketone bodies in a low CHO/ high fat environment
What hormone promotes ketogenesis?
Glucagon
What is Lipogenesis?
Acetyl CoA → Fatty Acids (which bind with glycerol to be stored as triglycerides)
Which hormone is dominant and promotes Lipogenesis?
Insulin
What is Ketogenesis?
When ketone bodies are formed in the liver from the break down of fatty acids, where fat is the primary source of energy or in a fasted state.
What is Ketosis?
A state in which ketone bodies are able to be measured in the blood
What are the 3 types of ketone bodies?
Acetone
Aceto-acetate
Betahydroxybutyrate
What is Ketoacidosis?
A state where the concentrations of ketone bodies is so high that the pH of the blood begins to fall
What happens to amino acids once they reach the cells?
They undergo deamination, where the amine group is removed leaving behind a carbon skeleton
What is the difference between ‘ketogenic amino acids and ‘glucogenic amino acids’?
The carbon skeletons of ketogenic amino acids form Acetyl CoA which can enter the CAC or form ketone bodies
The carbon skeletons of glucogenic amino acids form pyruvate or oxaloacetate (or other intermediates of the CAC) which act as fuels to make ATP
What is gluconeogensis?
The formation of new glucose from non-glucose sources (reverse glycolysis)
What are the 3 main regulators of energy metabolism?
1) The liver and substrates
- major site of nutrient conversion and storage
2) ATP ‘status’
- High ADP/AMP : ATP ratio activates AMPK to promote nutrient catabolism to increase ATP production
3) Functioning Enzymes, Hormones and Vitamins
- rate limiting
- no calories but essential
During a feasted state the enzymes for which pathways are unregulated?
- glycogenesis
- lipogenesis
- protein synthesis
- urea synthesis
What is the dominant hormone in a post-prandial state?
Insulin
What begins to happen in a fasted state?
1) hepatic glycogen breakdown to maintain BG levels
2) muscle glycogen provides energy for muscles only
3) Protein breakdown as a substrate for gluconeogenesis
4) Fat breakdown becomes main energy source in extended fasting
5) Ketogenesis: ketone bodies become an alternate source for brain/muscles etc. to preserve muscle mass
