Biochemistry of Nutrition

bsmith.1994
Mind Map by bsmith.1994, updated more than 1 year ago
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Degree Core Biochemistry (Protein Structure & Function) Mind Map on Biochemistry of Nutrition, created by bsmith.1994 on 04/11/2014.

Resource summary

Biochemistry of Nutrition
1 1.5 billion people in the world obese, meanwhile 925 million underweight
2 Vitamins
2.1 Organic compounds not synthesised in the body
2.2 required in ug/mg
2.3 deficiency causes disease, which are treated by restoring levels through ingestion
2.4 can be water or fat soluble
2.4.1 B vitamins and vitamin C water soluble
2.4.2 Vitamins E, K, A, D all fat soluble
2.5 B Vitamins
2.5.1 Thiamin (B1)
2.5.1.1 Converted to thiamin pyrophosphate (TPP)
2.5.1.1.1 TPP is a vital cofactor used by pyruvate dehydrogenase
2.5.1.1.2 other enzymes involving oxidative decarboxylation also use TPP, such as a-ketoglutarate dehydrogenase
2.5.1.2 thiamin deficiency causes beri-beri
2.5.1.2.1 symptoms include muscle weakness from nerve damage
2.5.2 Riboflavin (B2)
2.5.2.1 constituent of flavin coenzymes (FAD/FMN)
2.5.3 Niacin (B3)
2.5.3.1 nicotinamide/nicotinic acid components of NAD(P)H
2.5.3.1.1 nicotinic acid lowers LDL-C and raises HDL-C
2.5.3.1.2 nicotinamide is used to treat skin and neurological disorders
2.5.3.1.3 prolonged high dosage of either can result in liver damage
2.5.3.2 can be synthesised in the body from tryptophan
2.5.3.3 deficiency causes pellagra
2.5.3.3.1 symptoms include: sunburn-like rash, diarrhoea, depressive psychosis, eventual death
2.5.4 Pantothenic acid (B5)
2.5.4.1 component of Coenzyme A
2.5.5 Biotin (B7)
2.5.5.1 used in either metabolism or transcription as part of the biotin cycle
2.5.5.1.1 prosthetic group for carboxylases
2.5.5.1.2 histone proteins in nuclesomes
2.5.5.1.3 biocytin (biotin covalently bonded to a lysine) released during protein turnover, converted back to biotin via biotinidase
2.5.6 Vitamin B6 (Pyridoxine)
2.5.6.1 required in many parts of metabolism
2.5.6.2 converted to pyridoxal-5'-phosphate (PLP), which is required for over 100 enzyme functions
2.5.6.2.1 transamination
2.5.6.2.2 glycogen breakdown
2.5.6.2.3 haem synthesis
2.5.6.2.4 neurotransmitter synthesis
2.5.6.2.4.1 serotonin
2.5.6.2.4.2 dopamine
2.5.6.2.4.3 noradrenalin
2.5.6.2.4.4 GABA
2.5.6.2.5 modulates action of steroid hormones
2.5.6.2.5.1 oestrogen
2.5.6.2.5.2 testosterone
2.5.7 Vitamin B12
2.5.7.1 large complex with cobalt (III) ion
2.5.7.2 crucial for 2 enzymes

Annotations:

  • methionine synthase L-methylmalonyl-CoA mutase
2.5.7.3 found only in animal sources
2.5.7.4 bound in stomach to R-binding protein, which is degraded as B12 reaches the duodenum, so it can be absorbed in the small intestine via intrinsic factor
2.5.7.4.1 problems with this pathway lead to macrocytic anaemia and neurological problems
2.5.7.5 needed for the recycling of folate
2.5.7.6 all linked in pathways for DNA methylation
2.5.8 Folic acid (B9)
2.5.8.1 key to 1 carbon transfers
2.5.8.1.1 tetrahydrofolate is main molecule involved in this process
2.5.8.1.2 key to biosynthesis of several molecules, inlcluding dTMP, that regenerates folate

Annotations:

  • other include serine, methionine, glycine, choline and purine nucleotides
2.5.8.1.2.1 during this process, THF donates a methylene and is oxidised to DHF, dihydrofolate reductase is required to reduce it back to THF, any absence of this inhibits DNA synthesis so is a target for cancer therapy

Annotations:

  • methotrexate aminopterin trimethoprim
2.5.8.2 deficiency leads to megaloblastic anaemia and neural tube defects (spinal bifida)
2.5.9 water soluble
2.6 Vitamin C (ascorbic acid)
2.6.1 large role in collagen synthesis, coenzyme for prolyl hydroxylase and lysyl hydroxylase
2.6.1.1 prolyl hydroxylase involved in hydroxyproline synthesis, which stabilises the collagen triple helix
2.6.1.2 lysyl hydroxylase involved in hydroxylysine synthesis, which aids cross-linking between chains
2.6.2 deficiency leads to scurvy, which results in weak collagen
2.6.2.1 symptoms include fatigue, joint pain, muscle weakness, haemhorrhages, gum disease
2.6.3 excess vitamin C consumption can cause kidney stones
2.7 Vitamin E (a-Tocopherol)
2.7.1 protect from free radicals - antioxidant
2.7.2 protect from lipid peroxidation in membranes
2.7.3 fat soluble
2.8 Vitamin A
2.8.1 derived from dietary B-carotene
2.8.2 B-carotene dioxygenase in intestines cleaves to form retinal
2.8.2.1 retinaldehyde reductase forms retinol using NADPH
2.8.2.1.1 esterified to palmitic acid
2.8.2.1.1.1 in to chylomicrons, which transport it to liver, retinol is taken up in the liver by RBP
2.8.3 retinol condenses with a lysine on opsin in rod cells to form rhodopsin
2.8.4 deficiency leads to poor vision then blindness
2.9 Vitamin K
2.9.1 phylloquinone in plants
2.9.2 menaquinone in intestinal bacteria
2.9.3 coenzyme for carboxylases, forming y-carboxyglutamate from glutamate
2.9.4 factors requiring vitamin K involved in coagulation
2.9.5 Warfarin is an anticoagulant that prevents regeneration of active vitamin K
2.10 Vitamin D
2.10.1 cholesterol is a precursor for vitamin D synthesis
2.10.2 7-dehydrocholesterol is converted to cholecalciferol (D3) on the skin through the action of UV radiation
2.10.2.1 cholecalciferol is converted to 25-hydroxyvitamin D3 (calcidiol) in the liver
2.10.2.1.1 calcidiol is converted to 1, 25-dihydroxyvitamin D3 (calcitriol) in the kidney, this is the biologically active form
2.10.2.1.1.1 circulates as a hormone in the blood
2.10.2.1.1.2 regulates calcium/phosphate in bloodstream
2.10.3 deficiency causes bone disease (osteomalacia/rickets)
2.10.3.1 also linked to cancer risk
3 Minerals
3.1 inorganic elements with physiological function
3.2 required in varying amounts
3.2.1 ug of 'trace' elements
3.2.2 g of Na/Ca/K/P
3.3 Iron
3.3.1 found in haem proteins and electron carriers (cytochrome)
3.3.2 deficiency leads to anaemia
3.3.3 binds to oxygen
3.4 Calcium
3.4.1 involved in several processes
3.4.1.1 cell signalling
3.4.1.2 neural transmission
3.4.1.3 muscle function
3.4.1.4 membrane/cytoskeletal function
3.4.1.5 blood coagulation
3.4.2 hypocalcaemia leads to muscle cramps/spasms
3.4.3 calcium levels controlled by parathyroid hormone
3.5 Iodine
3.5.1 vital for thyroid hormones function
3.5.2 inadequate iodine during pregnancy affects cognitive development of foetus
3.6 Cobalt in nitrile hydratase
3.7 Copper in oxidoreductases
3.8 Zinc in proteases
3.9 Selenium in glutathione peroxidase
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