Fat Soluble Vitamins

Question 1

Vitamin A

Answer 1

-difference is based on oxidation degree of terminal alcohol functional group
-roles of retinoids include embryonic development, adult growth and development maintenance, maintenance of immunity and vision
-retinal is essential for vision
-cells of the retina contain rhodopsin, a molecule made up of a protein and a cis-retinal. As rhodopsin absorbs light, retinal changes from cis to trans, which triggers nerve impulse that brings visual information to brain
-vit A can be stored in the body
-beta-carotene can be converted to vitamin A
-keeps the tissues healthy, helps bone growth and immune system
- carotenoids act as antioxidants because of their network of double bonds having very low activation energy for lipid peroxidation
-carotenoids prevent damage caused by singlet oxygen by quenching it
-antioxidants reduce concentration of reactive oxygen species

Question 2

Vitamin D3

Answer 2

-is formed in the skin
-essential in calcium absorption in the intestine
-deficiency can be caused by geographic latitude, time of year, diet, cloud cover and use of sunscreen
-vit D2 comes from plants sources, fortified foods and synthetic form
-vit D3 is the internal form mammals make and can only be found in animal foods
-main function is to maintain calcium and phosphorus homeostasis by increasing calcium absorption and phosphorus excretion in the kidney

Question 3

Vitamin E

Answer 3

-synthesized only by photosynthetic organisms
-methyl group position in aromatic portion of chromanl head group distinguishes the different types
-alpha-tocopherol is the only form used by the human body
-neutralizes unstable molecules that can damage cells
-enhances immune function and prevents clots from forming in heart arteries
-reduces free radicals that can cause early stage arteriosclerosis
-may help prevent Alzheimer’s

Question 4

Vitamin K

Answer 4

-is limited to use as a nutritional supplement in animal feed due to activity
-involved in post-synthesis modification of proteins required for blood coagulation and control binding of calcium in bones
-is a coenzyme for carboxylase which is the enzyme involved in synthesis of proteins for blood clotting and bone metabolism
-vit D and vit K behave synergistically: vitD produces osteocalcin and vitK carboxylates osteocalcin for improved bone function