bio1011

5r

. Are there different forms of the same vitamin?

• Yes. Some vitamins exist in multiple forms because each form has a different function.
  Example: Vitamin A → retinal (vision), retinoic acid (gene regulation), retinol (storage/transport).What are different names vitamins go by (ascorbic acid = ?)

What are different names vitamins go by (ascorbic acid = ?)

• Ascorbic acid = Vitamin C

• Retinol/retinal/retinoic acid = Vitamin A

• Cholecalciferol = Vitamin D₃

• Tocopherol = Vitamin E

• Phylloquinone = Vitamin K₁

• Niacin = Vitamin B3, Thiamin = B1, Riboflavin = B2

Which vitamins are stored and where?

• A, D, E, K → stored in liver + fat tissue.

• B12 → stored in liver for years.

Where do vitamins perform their jobs, especially Vitamin D?

Vitamin D target organs:

• Intestine: increases calcium absorption.

• Kidney: decreases calcium excretion.

• Bone: releases calcium to correct low blood Ca.

Purpose: regulate and maintain normal blood calcium.

Precursors (pro-vitamins) = inactive forms that must be converted to active vitamins.
Examples:

• β-carotene → Vitamin A

• 7-dehydrocholesterol (skin) → Vitamin D₃ with sunlight

• Tryptophan → Niacin

Needs: enzymes, functioning liver/kidney, sometimes UV light.

What are vitamin precursors and how do they become active?

Are precursors toxic like active forms?

No. Precursors are much less toxic because the body controls how much is converted.
Example: β-carotene is safe; retinol can be toxic.

What is a coenzyme’s role and which vitamins act this way?

Coenzymes help enzymes work by carrying electrons or chemical groups.
B-vitamins that act as coenzymes: B1, B2, B3, B5, B6, biotin, folate, B12.
They assist in energy metabolism, amino acid metabolism, DNA synthesis.