Unit 4: Catabolism of Food

Question 1

What are carbohydrates broken down into?

Answer 1

1. polysaccarides

2. mono and di saccarides

Question 2

What happens to polysaccarides when they are catabolized?

Answer 2

They are hydrolyzed by enzymes to release glucose. The glucose enters glycolysis

Question 3

What happens to mono and di saccarides when they are catabolized?

Answer 3

1. sucrose is hydrolyzed by enzymes into glucose and fructose
2. glucose enters glycolysis directly
3. Pi is added to fructose to form fructose-6-phosphate, which can enter glycolysis

Question 4

What are proteins broken down into?

Answer 4

Chains of amino acids

Question 5

What happens to chains of amino acids when they are catabolized?

Answer 5

1. Hydrolyzed by proteolytic enzymes which remove amino acids
2. IF protein is used for energy production then the amino group is removed (deamination). Ammonia is formed, is transformed into urea and is excreted in urine
3. The remaining molecule after deamination is modified and enters the citric acid cycle

Question 6

What are fats broken down into?

Answer 6

Triglycerides composed of 1 glycerol and 3 fatty acid chains

Question 7

What happens to the glycerol when it is catabolized?

Answer 7

Glycerol is removed and is converted into GAP (G3P) and enters glycolysis

Question 8

What happens to fatty acids when they are catabolized?

Answer 8

Fatty acids undergo b-oxidation and form 3 2-carbon molecules which are each turned into acetyl CoA and enter the citric acid cycle.

Question 9

How many ATP molecules are made from fatty acid chains?

Answer 9

15 ATP molecules