vitamins and coenzymes

Question 1

cofactors vs coenzymes

Answer 1

both are non protein constituents of enzymes. cofactors are additional chemical components usually metal ions required for some enzyme’s activity. eg are Fe2+ and Mg2+.
coenzymes are complex organic or metalloorganic molecules which act as transient carriers of specific fundtionl groups

Question 2

examples of coenzymes

Answer 2

coenzyme A with carries acyl groups
FAD adn NAD which carry electrons
pyridocal phospahate which carries amino groups and tetrahydrofolate which carries 1 carbon groups.

Question 3

2 types of coenzymes

Answer 3

when they only transiently associate with the enzyme they are called cosubstrates, when permenantly bound they are prostethic groups

Question 4

apoenzyme plus cofactor forms a?

Answer 4

holoenzymes- active form

Question 5

magnesium in hexokinase

Answer 5

the positive magnesium group works to attract the negative oxygens of the phosphate groups in ATP towards it for the hydroxyl group of glucose to attach to the partial psoitive phosphorus in the centre.

Question 6

about fat soluble and water soluble vitamisn

Answer 6

fat soluble include vitamin A (retinol and beta carotenes), D (cholecalciferol), K (phylloquinones and menaquinones), E ((tocopherols).
vit K is the only fat solubel coenzymes, and a cofactor

water soluble ones all act as cofactors or enzymes.
vitamin C- ascorbic acid
and the B compelxes

Question 7

name the vitamin B complexes

Answer 7

b1 thiamine
b2 riboflavin
b3 niacin
b5 pantothenic acid
b6 pyridoxine
b7 biotin
b9 folate
b12 cobalamin

Question 8

pernicious anemia

Answer 8

lead by a deficieny of vitamin B12. the lack of B 12 is caused by malabsoption of the vitamin due to autoimmune destruction of the gastric parietal cells.
the methylation reaction of hoomocysteine into methionene requires methionine syntahse enzyme and B12 cofactor. here cobalamin obtains the methyl group from the coupled reaction of 5-methyltetrahydrofolate into THF. If B12 is unavailable, folate is trapped in methylthf form as no other conversions of methylthf are reversible.
This lack of B12 therefore leads to
- homocysteine cannot be converted to methionine–> methionine deficiency
- folate trapped as methylthf therefore–> deficiency of THF and all its other forms

decrease in other forms of THF leads to lack of purine and pyramidine synthesis and thymidine monophosphate synthesis which impairs dna synthesis. seen as megaloblastic anemia symptoms

Question 9

megaloblastic anemia

Answer 9

seen by deficiency of B12 and B9 and characterizied by macrocytic rbc–> large immature rbc precursors known as megaloblasts. lack of those vitamisn leads to imparied dna synthesis and nuclear division. cytoplasmic maturation is not affected which leads to asynchronous maturation –> leads to rbc large size.

Question 10

reaction of folic acid to thf

Answer 10

folic acid is reduced to duhydrofolic acid using dihydrofolate reductase, producing NADP+. dihydrofolic acid si reduced to THF using the same enzyme and also producing NADPH+

Question 11

voitamin c

Answer 11

coenzyme in hydroxylation reactions such as those of proline , lysine
reducing agent in various reactions.

Question 12

nadh and nadph

Answer 12

serve as coenzymes in oxidstion reduction reactions where the coenzymes undergo reduction of the pyridine ring by sccepting s hydrige ionx