Metabolism

Question 1

What is the fate of exces dietary carbohydrates, proteins and fats?

Answer 1

They are converted into triglycerides

Question 2

list the pathway that certain amino acids can ungergo to be converted to triglycerides

Answer 2

Amino acid –> acetyl CoA –> fatty acids —> triglycerides.

Question 3

what are the two pathways in which glucose is converted to form lipids?

Answer 3

1. glucose -> glyceraldehyde 3-phosphate -> glycerol
2. glucose ->glyceraldehyde 3-phosphate -> acetyl CoA -> fatty acids.

Question 4

How are triglycerides and cholosterol transported in blood?

Answer 4

They are combined with proteins to make them water soluble resulting in the formation of lipoproteins.

Question 5

list the four major types of lipoproteins

Answer 5

chylomicrons- transport dietary lipids to adipose tissue for storage

very low density lipoproteins - transport triglycerides made in liver cells to adipose cells for storage

low density lipoproteins - transport 75% of cholesterol

high density lipoproteins - remove excess cholesterol from the body and transport it to the liver for elimination

Question 6

what are amino acids used for ? What happens to excess amino acids?

Answer 6

Amino acids are oxidised to produce ATP

Used to synthesize new proteins for growth and repair of body tissue.

excess amini acids are converted to glucose (gluconeogenesis) or triglycerides.

Question 7

List the functions of Proteins

Answer 7

Enzymes

transportation eg haemoglobin

antibodies

clotting factors eg fibrinogen

hormones eg insulin

contractile elements in muscle fibres (actin and myosin)

structural componenets ( collagen , elastin and keratin)

Question 8

what is deamination and where does it occur?

Answer 8

deamination is the removal of the amino group from amino acids.

It occurs in the liver and results in the production of ammonia

liver cells convert the highly toxic ammonia to urea which is harmless and is excreted as urine.

Question 9

How are new proteins formed?

Answer 9

formation of peptide bonds between amino acids to form new proteins is carried out by ribosomes . ribosomes are found in all cells of the body and are directed by DNA and RNA.

Question 10

list hormones responsible for protein synthesis

Answer 10

thyroid hormones

insulin

oestrogen

testosterone