Vitamin C

Question 1

What is another name for Vitamin C?

Answer 1

ascorbic acid

Question 2

What is the history of Vitamin C? How was it discovered?

Answer 2

Multiple animal studies were conducted (chickens, monkeys, mice, etc.) that had inconclusive findings for scurvy.

Guinea pigs were used in an experiment and allowed for the discovery of vitamin C deficiency is the cause of scurvy. This is because guinea pigs are also deficient in synthesizing the enzyme necessary for creating our own source of vitamin C. This means that it must be consumed in the diet.

Question 3

Why is vitamin C an essential nutrient for humans?

Answer 3

• we lack the enzyme to make it ourselves (synthesize)
• must be consumed in the diet
• most mammals can make it but we (among guinea pigs) cannot

Question 4

Know the differences in function (and localization) between the two vitamin C transport proteins.

Answer 4

SVCT1 - sodium-dependent vitamin transporter 1
Function: involved in whole-body homeostasis of vitamin C
Location: epithelial cells (intestine, liver and kidney)

SVCT2 - sodium-dependent vitamin transporter 2
Function: protects metabolically active cells against oxidative stress
Location: non-epithelial cells (brain, lung, heart, eye, placenta)

Question 5

What are the two primary classifications of vitamins for vitamin C?

Answer 5

• antioxidants

- coenzyme (hydroxylation of enzymes)

Question 6

How is the function of vitamin C similar to/different to riboflavin?

Answer 6

vitamin C and riboflavin are both water-soluble vitamins

• vitamin C donates electrons
• riboflavin accepts electrons

They both play a protective role from reactive oxygen species

Question 7

What is the metabolic role of ascorbic acid in the synthesis of collagen proteins?

Answer 7

• keeps iron in the reduced state
• ascorbic acid is the essential cofactor for the two enzymes required for a collagen synthesis
• prolyl hydroxylase
• lysyl hydroxylase