Topic 3 Cellular Respiration: Alternative Energy Source (when glucose supply low)

Question 1

• After large meals insulin stores glucose as glycogen. Glucagon has the opposite effect and turns on glycogen degradation
• Insulin activates PFK enzyme and glucagon inhibits it
• Disaccharides are hydrolyzed into monosaccharides
• All cells are capable of storing glycogen, but only skeletal muscle cells and liver cells store large amounts

Answer 1

First would use other carbohydrates

Question 2

• Store more energy than carbohydrates
• Carbons in a more reduced state
• Lipases in adipose tissue are hormone sensitive to glucagon
• Glycerol -> PGAL, enter glycolysis
• When fatty acid -> acetyl CoA, every 2 carbon from fatty acid chain makes acetyl CoA
• Fatty acids in blood combine with albumin which carries them to bloodstream
• Fatty acids are broken down for energy
  a. 2 ATP are spent activating the fatty acid chain
  b. Saturated fatty acids produce 1 NADH and 1 FADH2 for every cut into 2 carbons
  c. Unsaturated fatty acids produce 1 less FADH2 for each double bond
  d. Results in a yield for ATP, as it yields more ATP per carbon than carbohydrate, with more energy in fats than sugars
• Between meals, lipids of plasma are in the form of lipoproteins
  a. Chylomicrons are low and high density lipoproteins. LDLs contain low protein density but high fat density and we unhealthy. HDLs contain high protein density but low fat density and are healthy.

Answer 2

Second would use Fats

Question 3

• Least durable source of energy, and is used when carbohydrates and fats are unavailable
• Most amino acids are deaminated in the liver and then converted to pyruvate, acetyl CoA, or other Krebs intermediates. They then enter cellular respiration
  a. Oxidative deamination removes ammonia molecule from amino acids. Ammonia is toxic to vertebrates.
  b. Insects, birds, and reptiles convert ammonia to uric acid while mammals, sharks, and most amphibians convert to urea for excretion.

Answer 3

Third would be Protein