Carbohydrates 2a - Glycolysis and Gluconeogenesis

Question 1

What is Glycolysis?

Answer 1

The cellular degradation of the simple sugar, glucose , to yield ATP as an energy source.

Question 2

Why is glycolysis so important?

Answer 2

It is essentially the only way that energy can be made from fuel molecules when cells lack O2

Question 3

Where does glycolysis take place?

Answer 3

occurs in the cytosol

Question 4

Using standard delta G values of glycolysis is it positive or negative?

Answer 4

Highly negative (giving up a large amount of energy)

Question 5

Which tissues rely completely on glucose as their main source of energy?

Answer 5

Brain
Nervous system
RBC’s
Testes
Embryonic tissues

Question 6

How much sugar does your body need and where is it stored?

Answer 6

Just your brain needs 120 g of sugar a day out of the 160 g for the whole body
The body has, approx. 20 g of free glucose in tissues
190 g can be produced from glycogen stores
So, there’s enough to cover the 160 g daily requirement

Question 7

why is gluconeogenesis not a reverse of glycolysis?

Answer 7

7 out of 10 glycolysis reactions are reversible
Large –ve ΔG prevents these reactions being reversible

Question 8

How does the cell make glucose again from pyruvate?

Answer 8

The cell bypasses these reactions with enzymes that catalyse a separate set of irreversible reactions
This causes glycolysis and gluconeogenesis to be irreversible processes