26/27. Ascorbic acid (vitamin C)

Question 1

Structure of vitamin C:

Answer 1

-

Question 2

what form of vitamin C is biologically active?

Answer 2

Both ascorbic acid and dehydroascorbic acid. -

Question 3

Metabolism of vit C: (facts)

Answer 3

Absorption in the intestines, you find it in fresh fruits (orange,citrus) , biosynthesis in plants, no storage. In man guinea pig and monkey the process of transport is energy requiring, but in other it is transported by passive transport.

Question 4

Metabolism of vit C: (synthesis)

Answer 4

-

Question 5

where is the highest concentration?

Answer 5

-Pituitary -adrenal -corpus luteum

Question 6

Biochemical role:

Answer 6

-Effective reducing agent. -Fasilitates the absorption of iron -Antioxidant effect -hydroxylase enzymes - corticosteroids 1.collagen synthesis 2.steroid hormone synthesis 3.serotonin synthesis 4.Tyrosine degradation 5.Iron metabolism

Question 7

Deficiency:

Answer 7

Scurvy - hemorrhage, weak bones, anemia, defect CT. Farm animals: weak, fatigue, swine and cattle are under heat stress.

Question 8

1.collagen synthesis

Answer 8

Hydroxylation of proline and lysine –> hydroxy-proline or lysine. Need O2 and ascorbic acid.

Question 9

2.steroid hormone synthesis

Answer 9

Hydrolase enzymes, mitochondrial and microsomal steroid hydrolases, in the adrenal gland –> formation of corticoids which is impair in scurvy, it is reserved by ascorbic acid.

Question 10

3.serotonin synthesis

Answer 10

-Tryptophan –(hydrolase)–>5’hydroxytryptophan–decarboxylation–> serotonin. Important for blood pressure and respiration.

Question 11

4.Tyrosine degradation

Answer 11

-CNS Tyrosine helps make several important substances, including: Dopamine, Adrenaline and noradrenaline, Thyroid hormones, Melanin

Question 12

5.Iron metabolism

Answer 12

-Fe2+ is absorbed, ascorbic acid reduce Fe3+ to Fe2+, also helps the mobilization.