Proteins: Biochemistry of Nutrition Flashcards
What are macronutrients?
Proteins, carbohydrates and fats they supply energy blocks for anabolic reactions, excess intake leads to gain in weight.
What are micronutrients?
Vitamins and minerals.
Vitamins are organic compounds required for normal metabolic function, which cannot be synthesised in the body and deficiency results in disease.
Minerals: inorganic elements which have a physiological function.
What does the reference nutrient intake (RNI) for a micronutrient mean?
It is the amount required to meet the requirements of 97.5 % of the population.
What does vitamin B1 (Thiamin) deficiency cause?
Beri-beri: muscle weakness due to nerve damage, the heart can be affected.
In developed countries thiamin deficiency is mostly seen in alcoholics.
What is vitamin B2?
Riboflavin: a constituent of the flavin coenzymes FAD and FMN.
What does vitamin B3 (Niacin) deficiency cause?
Pellagra: dermatitis, diarrhoea, depressive psychosis and death.
What can vitamin B3 do in pharmalogical doses?
Nicotinamide: range of properties, used to treat skin and neurological disorders. Prolonged high dosage can cause liver dosage.
Niacin: lowers LDL-cholesterol and triglycerides. But raises HDL-cholesterol.
What is vitamin B7?
Biotin
What is biotin used in?
A prosthetic group for carboxylase, a carbon dioxide carrier, biotinylation in Histones, in the biotin cycle and deficiency is linked to birth defects in mice.
What is B6?
Pyridoxine, required for many aspects of metabolism. Severe deficiency is uncommon but inadequate intake may be common.
What is B12?
The largest B vitamin and contains a cobalt ion. Required for two enzymatic reactions in humans: methionine synthase and L-methylmalonyl-CoA mutase.
What can deficiency in B13 cause?
Untreated causes death. Pernicious and microcytic anaemia (inability to absorb) causes neurological symptoms, limb weakness, poor coordination and altered gait.
What is Folic acid key to?
One-carbon transfers in synthesis of serine, methionine, glycine, choline, purine nucleotides and dTMP.
What does deficiency of folate acid cause?
Megoblastic anaemia, similar to B13 deficiency but no neurological problems in adults.
What is vitamin C required for?
A coenzyme for prolyl hydroxylase and lysyl hydroxylase during collagen synthesis. Also involved in bile acid and adrenalin synthesis. May have antioxidant roles.
What does deficiency in vitamin C cause?
Scurvy which is abnormally weak collagen causes fatigue, joint pain, muscle weakness, poor healing, skin haemorrhages, gum disease etc. Untreated is fatal as damage and bleeding occurs in heart muscle.
What does vitamin E do?
Protects from free radicals and it’s main role is to protect against lipid oxidation in membranes.
What are the roles of vitamin A?
Possible antioxidant protection from CVD and cancer, helps vision in dim light.
Excess in pregnancy can cause foetal malformations.
Describe vitamin K?
Required for coagulation, found in two forms phylloquinone from plants and menaquinone synthesised from intestinal bacteria.
What is a precursor of vitamin D synthesis?
Cholesterol.
What does vitamin D do?
Acts as a transitional regulator for synthesis of a range of proteins involved in calcium homeostasis and bone growth/maintenance: binds to receptors in the nucleus, increases calcium and phosphate absorption from the intestine and can mobilise calcium ions from bones if in short dietary supply. Controls over 200 genes.
What are vitamin D deficiencies?
Osteomalacia (in adults)/ rickets (in children), may be implicated in cancer, insufficiency in type one diabetes, rheumatoid arthritis, systemic lupus erythematosis, multiple sclerosis and Crohn’s disease.
What mineral deficiencies are the greatest global concern?
Iron and Iodine.
Estimated that 2 billion people suffer from iron deficiency anaemia and 740 million from iodine deficiency.
What are the roles of iron?
Components of electron carriers (eg. cytochromes) which are key to many processes including the ETC. Component of haem (myoglobin, haemoglobin and haem -containing enzymes).
