Term
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Definition
| Organic molecules required in small amounts to maintain life. They are essential as they cannot be made by the human body. |
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Term
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Definition
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Term
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Definition
| C, B6, B12, Biotin, Folate, Niacin, Pantothenic acid, Riboflavin B2, Thiamin B1, |
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Term
| Fate of excess water soluble vitamins |
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Definition
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Term
| Relative toxicity of water soluble |
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Definition
| Less toxic generally than fat soluble |
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Term
| Fate of excess FAT soluble vitamins |
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Definition
| Accumulate in adipose tissue and can reach toxic levels |
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Term
| What must be present in the diet for fat soluble vitamins to be absorbed? |
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Definition
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Term
| Which vitamin type takes longer to become deficient? |
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Definition
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Term
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Definition
| Fruits, vegetables and liver |
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Term
| Function of vitamin c (3) |
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Definition
1. Antioxidant
2. Synthesis of biomolecules
3. Iron absorbtion |
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Term
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Definition
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Term
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Definition
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Term
| Symptoms of vit C deficiency (4) |
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Definition
1. Loose teeth
2. Poor healing
3. Fragility of blood vessels
4. Mild anaemia |
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Term
| Amino acids involved with collagen synthesis? |
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Definition
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Term
| What are proline and lysine converted to in collagen synthesis? |
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Definition
| Hydroxyproline and Hydroxylysine |
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Term
| What do the hydroxylase enzymes require for this process? |
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Definition
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Term
| What does vit C prevent occuring? |
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Definition
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Term
| Without vit C what does not properly form? |
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Definition
| Hydrogen bonds between collagen chains |
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Term
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Definition
| In the skin with the help of sunlight |
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Term
| Relative toxicity of vit D? |
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Definition
| Most toxic of all vitamins |
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Term
| Why is exposure to sunlight needed? |
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Definition
| Natural diets typically do not contain adequate quantities of vit D |
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Term
| Which molecule is required from the liver as a precursor to Vit D? |
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Definition
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Term
| What happens to 7-dehydrocholesterol? |
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Definition
| Ring cleavage to form inactive vitamin D |
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Term
| What happens to inactive Vit D to activate it? |
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Definition
Two Hydroxylations
OH added to C1 and C25 to produce 1,25-dihydroxyvitamin D |
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Term
| Folate (folic acid) source |
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Definition
| green leafy vegetables, liver & nuts |
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Term
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Definition
| Carrier of 1 carbon units |
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Term
| Deficiency manifestations (3) |
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Definition
1. Megaloblastic anaemia hair loss
2. fatigue
3. birth defects (spina bifida) |
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Term
| Symptoms of B group vitamin deficiency (folate is B vitamin) (3) |
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Definition
1. Glossitis
2. Recurrent apthous stomatits
3. Angular chelosis |
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Term
| Why does folic acid need activating |
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Definition
| Folic acid is not the active form of the vitamin. It needs reducing to tetrahydrofolate |
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Term
| What is used as a reducing agent for folate? |
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Definition
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Term
| What enzyme uses NADPH to as two hydrogens at a time to folate? |
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Definition
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Term
| How many times in folate reduced by dihydrofolate reductase? |
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Definition
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Term
| What is beneficial about dihydrofolate in microorganisms? |
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Definition
| It is in a different form to human dihydrofolate so can be inhibited with drugs which have little effect on humans. |
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Term
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Definition
| Coenzyme in reactions involving the transfer of a 1 carbon unit to other compounts |
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Term
| Which part of the tertrahydrofolate molecule carries the extra carbon? |
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Definition
| N5, N10 or bridged between both |
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Term
| Important example of tetrahydrofolate function |
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Definition
| Synthesis of Deoxythymidylate (dTMP) which is the T base in DNA |
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Term
| Methyl group + tetrahydrofolate in sythesis of deoxythidylate |
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Definition
| N5, N10- methyltetrafolate |
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Term
| For which types of cells in N5,N10-methyltetrahydrofolate important |
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Definition
Rapidly dividing cells which require lots of nucleic bases forming:
Bone marrow, hair follicles, cancer cells |
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Term
| What production is inhibited in chemotherapy? |
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Definition
| Deoxythymidylate (dTMP) production |
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Term
| Drug used in chemotherapy? |
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Definition
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Term
| How does methotrexate inhibit deoxythymidylate (dTMP) production? |
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Definition
Binds to folate reductase 1000x stronger than folate.
This inhibits conversion of dihydrofolate to tetrahydrofolate.
Reduces amount of N5,N10-methyltetrahydrofolate for deoxythymidylate production which limits DNA synthesis and prevent rapid cell division. |
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Term
| What does the conversion of N5-methyltetrahydrofolate to tetrahydrofolate depend on? |
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Definition
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Term
| What happens if vitamin B12 is deficient? |
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Definition
| N5-methyltetrahydrofolate will no be able to be converted back to tetrahydrofolate which causing the tetrahydrofolate to become 'trapped' as N5-methyltetrahydrofolate: a.k.a. the folate trap |
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Term
| What can a vitamin B12 deficiency give the appearance of? |
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Definition
| Folate deficiency due to the folate trap |
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Term
| What is the danger of supplementing folate for a B12 deficiency? |
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Definition
| Folate trap will still occur so neurological damage will get worse. |
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Term
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Definition
| Only produced by microorganisms |
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Term
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Definition
| required for folate metabolism |
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Term
| What does B12 bind to, to allow absorption? |
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Definition
| Glycoprotein intrinsic factor (I.F.) in the stomach secreted by the parietal cells. |
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Term
| What happens to Vitamin B12-I.F. complex in the small intestine |
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Definition
| Recognised by mucosal cells and absorbed in final section of intestine |
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Term
| Beta Oxidation function of B12? |
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Definition
| Required in conversion of propionyl CoA to succinyl CoA |
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Term
| Manifestation of B12 deficiency in Beta Oxidation? |
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Definition
| Methylmalonyl CoA accumulates and demyelinates nerve cells causing neurological damage |
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