Week 7 - Nutrition,Vitamins

Question 0

What is the function of iron? What are the sources? What are the symptoms of you have a deficiency?

Answer 0

Function - required for synthesis of… - Hb (it’s the component of heme) - electron transport and oxidative phosphorylation - component of cytochromes Sources - meat, fish, eggs Deficiency - haemochromatosis (build up of iron over the years, inherited) Leads to oxidative damage, skin pigmentation, diabetes, heart failure, liver failure

Question 1

What is the function of Magnesium? What are its sources? Deficiency leads to what kind of symptoms?

Answer 1

Function Skeletal development Replication of DNA and RNA synthesis Co factor for ATP requiring enzymes Sources Spinach and leafy green veg - is the pigment in chlorophyll Also fish, meat Deficiency Muscle weakness

Question 2

How is iron regulated?

Answer 2

By hepcidin, a peptide hormone in the liver Hepcidin bind with ferraportin (which is the only cellular iron transporter) Ferraportin degrades as a result of hepcidin binding INHIBITING IRON EFFLUX ^^^ hepcidin, inhibits iron further - this happens in hypoxia, anaemia ____ hepcidin, means ferraportin not degraded, so iron can leave

Question 3

What is the function of calcium? What are its sources? Deficiency symptoms?

Answer 3

Function Maintenance of bones and teeth (calcium present in bones in the form of hydroxyapatite) Second messenger, Intracellular signalling Blood clotting Sources Milk, dairy By law bread is now fortified with calcium Deficiency May be due to a lack of vitamin D which is essential in absorption of calcium

Question 4

Outline calcium homeostasis, including the organs involved as well as the hormones

Answer 4

Calcium is kept under control (hormonally) by.. 1- parathyroid hormone, produced by the parathyroid glans 2 - calcitonin (produced in thyroid, which inhibits resorption of bone) 3 - vitamin D synthesised in the skin by UV radiation (see vitamin D flash card) A decrease in calcium leads to.. - Increased parathyroid hormone release - At the kidneys this lead to 1) increased calcium absorption 2) increased synthesis of vitamin D - At the bone this leads to… 1) increased osteoclasts activity meaning more Ca2+ resorption - Increased synthesis of Vitamin D leads to… 1) At the kidneys: more plasma Ca2+ 2) At the bone : Ca2+ reabsorption 3) At the GI, increased Ca2+ absorption Ultimate this all leads to increased Calcium, this negatively feeds back to the parathyroid glands leading to less parathyroid release

Question 5

What is the function of Vitamin D? What are its sources?

Answer 5

Function; Important in Ca2+ absorption in GI tract (as well as kidneys where calcium reabsorption is increased and Bone reabsorption is increased by PTH stimulation Sources; dietary vitamin D exists as either (vitamin D2) or (vitamin D3). Ergocalciferol (D2) is derived from the UV irradiation of the plant sterol ergosterol (D3 ) is formed from the action of UV irradiation on 7-dehydrocholesterol in the skin of animals including humans. Very little dietary vitamin D, is usually fortified in food by law

Question 6

Outline vitamin D metabolism

Answer 6

1) You get Vitamin D2, D3 from two places, a little from the diet but mostly, Vitamin D3 is a product of when the Uv Rays from the sun hit the skin steroid, 7 dihydrocholesterol. 2) metabolism begins in the liver, where an enzyme (25 hydroxylase) adds an OH group to carbon number 25 of vitamin d3. It becomes 25- hydroxycholecalciferol Travels in the bloodstream and gets to your kidneys .. 3) In the kidneys, 1 hydroxylase adds an Oh group to “. Making it.. 1,25 dihydroxycholecalciferol which is what causes increased calcium absorption in the intestines

Question 7

What are the different types of mutation and which is the most detrimental mutation?

Answer 7

Point mutation - missense - where one base in changed to another which codes for a different amino acid - nonsense - where one base sequence is changed which codes for a stop codon, shortening the amino acid - silent - where one base sequence is changed but the triplet code still codes for the same amino acid Insertion mutation Insertion of base sequence changes reading frame and all triplet codes and their fore all amino acids being coded for change. The same occurs during a deletion mutation as the base sequence is deleted -

Question 8

What are the different types of mutation and which is the most detrimental mutation?

Answer 8

Point mutation - missense - where one base in changed to another which codes for a different amino acid - nonsense - where one base sequence is changed which codes for a stop codon, shortening the amino acid - silent - where one base sequence is changed but the triplet code still codes for the same amino acid Insertion mutation Insertion of base sequence changes reading frame and all triplet codes and their fore all amino acids being coded for change. The same occurs during a deletion mutation as the base sequence is deleted -

Question 9

What is the function of the vitamin phosphorus? Name a source and deficiencies associated.

Answer 9

Function; Structural material in bones and teeth 80% of phosphorus is present in the body as calcium salts in bone Source; Red meat, dairy products Deficiency; Decaying teeth

Question 10

What is the function of iodine, name a source.

Answer 10

Function; Constituent of thyroid hormone e.g. Thyroxine which are important in regulating metabolic rate Source; Seafood, dairy

Question 11

What is the function of zinc, name a source

Answer 11

Function; co factor of many enzymes, involved in many metabolic pathways (carbohydrate, protein, lipid) Maintenance of wound healing Source; Meat, dairy foods

Question 12

Function and source of copper?

Answer 12

Associated with cytochrome c oxidase Component of many enzymes Involved in production of white blood cells and red blood cells Source; Nuts, cereals Deficiency; Anaemia

Question 13

Function and sources of Vitamin A?

Answer 13

Vitamin A can be derived in two ways; - Retinol (animal derived foods) - Carotenoids (usually plant derived) Function; Important in structure of Epithelia and mucous membranes Therefore vital for vision and growth Sources; Liver, whole milk, carrots

Question 14

What is the function and source of vitamin B1, B2, B3?

Answer 14

B1 (thiamin) __ Function ; Coenzyme for link reaction Thiamine derivative thiamine pyro phosphate ( TPP) is a coenzyme in metabolism of sugar and amino acids… It is used by private dehydrogenase to de carboxylate pyro ate in the link reaction B2 (riboflavin) ___ Function; - component of co factors: FMN and FAD - FMN in complex 1 and complex 3 in electron transport chain - oxidative phosphorylation Sources ; Eggs, milk B3 (niacin) ___ Precursor of NaD and NADP - involved in carbohydrate metabolism; Electron carriers and involved in oxidative phosphorylation Source; Meat,

Question 15

Function and source of vitamins B5, B6, B9, B12

Answer 15

B5 (pentothenic acid) ___ Require to synthesise cholesterol Constituent part of CoA Source; From a wide variety of food therefore known as ‘pantothen’ meaning everywhere Meat, eggs, cereal grains B6 — Has 3 forms Required by many enzymes mostly involved in protein metabolism Transaminases, decarboxylases have a central role in amino acid metabolism B9 (folic acid) — Function; Coenzyme - Required to synthesis thymine, guanine and alanine de novo, therefore important in Dna and RNA synthesis Regulation of transcription: extra folate means Dna synthesis is promoted and thus leads to proliferation of cancer cells - important to have at least 0.4 micrograms of folate during conception and pregnancy which prevents neural tube defects Source; Cabbage, folate means leaf B12 —- Normal bran/nervous system functioning Catabolism of propria ate which is important in gluconeogenesis (look this up!) Deficiency… Folic acid can compensate Source; Synthesis exclusive by microorganisms therefore all foods of animal origin have it

Question 16

Function and source of vitamin C?

Answer 16

Function; Redox reactions Converts fe3+ to fe 2+ Co factor in 8 enzymes Also, Collagen synthesis Activation of ACTH Carnotite formation Antioxidant - prevents photooxidative damage to the lens Source; Citrus fruits