Transformation of Biological Molecules

Question 1

gluconeogenesis

Answer 1

it is almost a reversal of glycolysis
7 step suse the same enzymes
however, some steps are not reversible
- pyruvate to phosphoenolpyruvate occurs via oxaloacetate
- fructose-1,6-biphosphate
- glucocse-6-phosphate conversions

glycerol can be converted into glucose from lipids (and other things when they are first converted into lipids)

Question 2

lipid metabolism

Answer 2

lipids are created from lipolysis using glycerol and fatty acids

glycerol can be created from glucose

fatty acids can be created from reverse beta oxidation
they can also be created from ketone bodies in reverse ketogenesis in the liver

Question 3

How are ketones created?

Answer 3

created from fatty acids in the liver through ketogenesis

created from acetyl coA through anabolic processes

When high levels of acetyl CoA are present in the cell, they enter the ketogenesis pathway, forming ketone bodies such as acetoacetate, which cause ketosis and acidosis

Question 4

What is B oxidation

Answer 4

The purpose of Beta Oxidation is to create Acetyl CoA in the absence of glucose in order to create ATP

The fatty acyl CoA is oxidised to yield a shorter fatty acyl CoA, acetyl CoA, and reduced coenzymes NADH and FADH2

Although the energy from a particular fatty acid depends on its length, each oxidation cycle yields 4 ATP with another 10 ATP from the acetyl CoA that enters the citric acid cycle

it makes the same amount of energy coming from fats or sugars, however, it is more complicated and that is why it isnt preferred

due to the irreversible nature of glycolysis it cannot be cycled back into glucose

Question 5

Cholesterol cycling

Answer 5

can be used to make steroids (anabolic)
can be used to make bile salts (catabolic)

Question 6

3 key things to remember in protein metabolism

Answer 6

○ There is no storage form of proteins. All protein is consumed. Excess proteins are turned into carbohydrates or fat and the nitrogen from the amino group must be eliminated through the urea cycle.
○ Essential amino acids must be consumed daily for protein to be made
○ Proteins are always being degraded, therefore there is a constant need for quality protein in order to maintain the body’s structure

Question 7

3 stages of protein metabolism

Answer 7

There are three main stages
○ Transamination
○ Oxidative deamination
○ Urea cycle