Vitamin A

Question 1

Types of Vitamin A

Answer 1

Vitamin Retinoids (animals): 1-3, Retinol fatty acid (animal food) - retinol - retinal - retinoic acid (final product) 
Provitamin A (plants): Carotenoids: beta-carotene (plant foods) - retinoic acid (final product in its active form)

Question 2

How much is 1mg of retinol equivalent to in beta-carotene?

Answer 2

1 mg of retinal is equivalent to 12 mg of beta-carotene

Question 3

Types of retinoids?

Answer 3

liver, fish oils, egg yolk, butter, milk

Question 4

Types of carotenoids?

Answer 4

dark greens, yellow vegetables and tomatoes

Question 5

Recommended daily allowence (RDA) for men and women?

Answer 5

For men they need 900 ug and women 700 (micrograms)

Question 6

Retinal and visual cycle?

Answer 6

1.) retinal (11-cis) and opsin bind together in the body. (rhodopsin) 2.) then light enters or in other words photon enters the body and causes a conformational change. This change is that it truns the rhodopsin from cis to trans. This sends a nerve impulse to the brain. 3.) this will then cause the retinal and opsin to unbind bc they are uncompatible and so the retinal will release and some of it will be lost from the cycle. 4.) the retinal that is lost is replaced from retinol in the blood.

Question 7

Purpose of the retinal cycle?

Answer 7

its purpose is to replenish the compounds needed for light to activate the receptors in the eye.

Question 8

What can deficiency of vitamin A cause?

Answer 8

deficiency can cause night blindness and severe deficiency can cause blindness as it is the most common cause of blindness in the world.

Question 9

Functions of retinoic acid?

Answer 9

Since it acts as a transcription regulator it has other functions:

1. ) Binds nuclear receptor (RAR)
2. ) regulates: genes regulating growth, embryonic development, and tissue differentiation
3. ) Decreases keratin synthesis in skin
4. ) antioxidant
5. ) used in medical treatment like those with excess keratin such as psoriasis or severe acne

Question 10

Is vitamin A toxic ?

Answer 10

Can be toxic if there is an excess adn tertogenic but thats almost impossible by ingesting normal food. Instead it would be from ingesting too much supplements and medical treatments.