Micronutrients 1: Water-soluble And Fat (lipid)- Soluble vitamins Flashcards
What are macronutrients?
Carbohydrates, fats and proteins and, in humans, the catabolism of macronutrients to supply energy is an important aspect of nutrition
What are micronutrients?
Vitamins and minerals, (vitamins) of which are compounds necessary for metabolic processes, but the body is either unable to synthesise them, or synthesise sufficient amounts for needs, so they must be obtained from dietary sources
What is the traditional role of a daily multivitamin?
To prevent nutritional deficiency
What are the general features of vitamins?
- Required in small amounts
- Are not building blocks for larger molecules
- Do not yield energy when broken down
- Humans need at least 12 vitamins in diet
How can vitamins be grouped?
Into water soluble and fat soluble
What are water soluble vitamins?
Vitamin B group, vitamin C
What are fat soluble vitamins?
Vitamins A, D, E and K
Which vitamins are highly variable in structure?
Water soluble
What vitamins are structurally similar and all isoprenoid compounds?
Fat soluble
Features of water soluble vitamins?
- Functional uniformity
- Carry mobile metabolic groups (activated carriers, co-enzymes)
- All except vitamin C require modification for function (precursor molecules)
- Readily excreted
- Labile- degraded
Features of lipid-soluble vitamins?
- Functionally diverse
- Not as readily absorbed/extracted from dietary foods
- Generally not co-enzymes/activated carriers
- Vit A, D act more like hormones (and are toxic in excess)
What are almost all activated carriers that act as co-enzymes derived from?
Vitamins
Co enzyme derived from riboflavin?
Flavin adenine dinucleotide (oxidation-reduction) deficiency leads to cheliosis and angular stomatitis (lesion of the mouth), dermatitis)
Co enzyme derived from nicotinic acid?
Nicotinamide adenine dinucleotide (oxidation reduction)
Coenzyme derived from folic acid?
Tetrahydrofolate (transfer of one carbon component- thymine synthesis)- deficiency leads to anemia, neural tube defects in development
What’s the function and deficiency of vitamin C (absorbed acid)?
Antioxidant
Scurvy (swollen and bleeding gums, subdermal hemorrhaging)
Function and deficiency of vitamin D?
Regulation of calcium and phosphate metabolism
Rickets (children); skeletal deformities, impaired growth
Osteomalacia (adults); soft, bending bones
Deficiency of vitamin A?
Night blindness, cornea damage, damage to respiratory and gastrointestinal tract
Deficiency of vitamin E?
Inhibition of sperm production
Lesion in muscles and nerves
Deficiency of vitamin K?
Subdermal hemorrhaging
Three forms of ascorbic acid? (Vitamin C)
Ascorbic acid
Ascorbate
Dehydroascorbic acid
What is ascorbate?
The ionised form of ascorbic acid
What is dehydroascorbic acid?
The oxidised form of ascorbate
Can humans synthesis vitamin c?
No
What step can humans not perform to achieve vitamin c biosynthesis?
The conversion of l-gulono-G-lactone into ascorbic acid
What catalysed the L-gulono-G-lactone into ascorbic acid?
The enzyme gulonolactone oxidase
Is the gene that codes for gulonolactone oxidase present in humans?
Yes, but it’s not active due to the accumulation of several mutations which have turned it into a non-functional pseudo gene
What are two common nutritional deficiencies?
- Famine
2. Vitamin C deficiency (scurvy- 2mill dead, 1:100,000 now- largely elderly, alcoholics and mental ill
Who discovered a treatment for scurvy?
James Lind (12 people trial with 6 different supplements)
What is vitamin C required for?
The formation of scar tissue
What is the amino acid structure of collagen?
Proline, hydroxyproline (abundant) and every third is a glycine (frequent tripeptide)- other amino acids present
What does extra cellular collagen contain?
Three helical peptide chains, each nearly 1000 residues long
What does the stabilisation of the collagen triple helix require?
Hydroxproline (which needs vitamin c for synthesis)
What is vitamin c?
An electron donor (reducing agent or antioxidant)
What does ascorbate interact with?
Enzymes having either monooxygenase or dioxygenase activity
What does vitamin c accelerate?
Hydroxylation in numerous bio synthetic pathways
What is one example of the ways vitamin c acts as an electron donor for 8 enzymes in humans?
Three participate in hydroxylation required for collagen synthesis
What requires vitamin c?
The hydroxylation of proline in collagen proteins to hydroxyproline
