Metabolism

Question 1

What are the 3 stages of metabolism?

Answer 1

1. Digestion
2. Storage and energy production
3. Catabolism for energy

Question 2

What is glycolysis, what is produced?

Answer 2

Splitting glucose
Series of enzymatic reactions which breaks glucose molecules
Generates;
4 ATP (but uses 2 ATP)

Question 3

What is the citric acid cycle, what is produced?

Answer 3

Products from glycolysis converted to Acetyl CoA
Enter the citric acid cycle (CAC/Kreb’s Cycle)
Produces
2 ATP
High energy electron carriers
Waste – CO2

Question 4

What is the electron transport chains, what is produced?

Answer 4

High energy electron carriers enter the ETC
- From Glycolysis and CAC

The high energy carriers drive enzymatic machinery
- ATP Synthase

Makes lots of ATP!
~28 ATP from NADH (24 ATP) and FADH2 (4 ATP) from CAC
- 4 ATP from NADH (from glycolysis)

Question 5

Explain the difference between aerobic and anaerobic respiration?

Answer 5

Complete catabolism of glucose is aerobic
-Meaning we need O2

In anaerobic conditions catabolism is incomplete
-Only glycolysis can proceed without O2
-But to enable this, must form lactic acid

Question 6

What is diabetes mellitus, and how does it effect BGLs and metabolism?

Answer 6

Diabetes mellitus (DM) is a disease of inadequate control of blood levels of glucose.
- Insufficient release of insulin by the pancreatic beta islet cells or resistance to insulin resulting in hyperglycaemia.

Question 6

Explain how our body deals with high BGL? (Hint: glycogenesis)

Answer 6

When the glucose level in the blood rises, the pancreas releases insulin. The insulin unlocks the cells so that glucose can enter. This provides the fuel the cells need to work properly. Extra glucose is stored in the liver and muscles.
(Homeostasis)

Question 6

What is a glycaemic index and what is the difference between low GI and high GI foods?

Answer 6

A measure of the rate of glucose absorption from the GIT.
High GI foods = chips, cake, ice cream, biscuit’s. Have a spike in glucose and faster drop.

Low GI foods = basmati rice,
vegetables, lentils, pasta, oats. Glucose lasts longer.

Question 7

Explain how our body deals with low BGL? (Hint: glycogenolysis and gluconeogenesis)

Answer 7

Homeostatic BGL
 BGL
Pancreas releases glucagon (alpha cells)
Nutrient metabolism
1. Liver releases glucose from glycogen stores
2. Fat mobilisation
 BGL
 Glucagon levels

Stimulate the release of glucose from stores in the body
Potentially use other nutrients to generate ATP
- Glycogenolysis
Freeing of glucose from glycogen
Reverse of glycogenesis
- Gluconeogenesis
Synthesis of glucose from alternative stores
Fats and proteins

Question 8

What happens when we use proteins and fats for energy?

Answer 8

Proteins get broken down into amino acids, which are the building blocks of the body. Fats get broken down into fatty acids for energy.

Only use these sources when no glucose/carbohydrates are left.