Vitamins 2

which type of deficiency is caused when there is a lack of sufficient quantities of a vitamin in diet?

primary

which two diseases are caused by a vitamin D deficiency?

rickets and osteomalacia

severe calcium and phosphate deficiencies can also cause which diseases?

rickets and osteomalacia

disease caused by reduced bone mass from aging or menopause (low estrogen) but which a deficiency of vitamin D can worsen

osteoporosis

disease which leads to softening or weakening of bones in children

rickets

disease which leads to softening or weakening of bones due to insufficient mineralization in adults

osteomalacia

besides a primary deficiency what else can cause rickets and osteomalacia?

malabsorption of vitamin D

a developing fetus is especially prone to a deficiency of which vitamin?

vitamin B9 (folic acid)

what type of deficiencies form due to disfunction in absorption?

secondary

vitamin D in connection to bone health

1. PTH increases bone …

2. vitamin D increases … of calcium/phosphate in the intestines

3. vitamin D increases … of calcium in the kidneys

4. vitamin D is essential for bone … and …

5. increased levels of … in the blood due to vitamin D suppress … and prevent excessive bone resorption

1. resorption

2. absorption

3. reabsorption

4. mineralisation and growth

5. calcium, PTH

parathyroid hormone (PTH) increases bone resorption by indirectly increasing … activity

(osteoblast/osteoclast)

osteoclast

which type of specialised cells are responsible for the removal and breakdown of bone tissue and maintaining calcium homeostasis by releasing calcium into the blood?

osteoclasts

which specialised cells are responsible for bone synthesis and mineralisation?

osteoblasts

mutations in or loss of enzymes which help convert vitamins into their active forms will manifest as … vitamin deficiencies (failure to process)

secondary

mutations or loss of proteins which transport water insoluble vitamin (DEKA) in the blood can contribute to … vitamin deficiencies (failure to transport)

secondary

which cells produce the intrinsic factor (IF) which binds B12?

parietal cells

what has to bind B12 before it can be absorbed in the GI tract?

IF

the IF-B12 complex is absorbed via which receptors on which cells and in which part of the GI tract?

cubulin receptors on enterocytes in the terminal ileum

many B12 deficiencies are caused by … against parietal cells

autoantibodies

4 other causes besides autoantibodies which can damage/remove parietal cells

1. bariatric surgery

2. gastric tumours

3. gastric ulcers

4. alcohol consumption

techincal term for having an abnormally high level of a specific vitamin in the body

hypervitaminosis

vitamin A acts as a transcription factor to suppress … activity and also stimulates … formation

(osteoclast/osteoblast)

osteoblast, osteoclast

what condition is often associated with an excess of vitamin A?

hypercalcemia

are lipid or water soluble vitamins stored for longer?

lipid

because primates and guinea pigs lost the last enzyme in the vitamin C synthesis pathway it means they don’t lack the … molecules but only the final product (vitamin C)

intermediate

the losses of genes coding for certain enzymes necessary for vitamin synthesis likely occured because diets reliably supplied these micronutrients so there was no … … to keep the full pathway

selective pressure

are coenzymes and cosubstrates protein or nonprotein?

nonprotein

2 examples of coenzymes we can synthesise

lipoic acid and CoQ

… + coenzyme → … (apo/holo)

apoenzyme + coenzyme → holoenzyme

which vitamins are examples of coenzymes? (mnemonic)

BACK

… acid has transcription factor activity and controls genes in embryonic development, male fertility, bone growth and immune function

retinoic

3 forms of vitamin A (the latter two being functional forms)

retinol, retinal and retinoic acid

vitamin A is derived from … (carrots)

beta carotenoids

types of rings where at least one atom is not carbon

heterocyclic

9 of 13 vitamins contain … rings

heterocyclic

… ring (in thiamine pyrophosphate) has a carbanion at C2, where the positive charge of the N atom stabilises the carbanion by resonance

thiazolium

the C atom in the thiazolium ring which can become a carbanion is sandwiched between … and … atoms

N and S

vitamin which is the precursor of FAD

riboflavin

which B vitamin is involved in amino group transfers? → involved in amino acid metabolism (answer with B#)

B6

which two vitamins are involved in redox reactions? → as NAD and FAD

B2 and B3

what is the metabolic role of thiamine pyrophosphate?

alpha keto acid decarboxylation and ketol group transfer

examples of two enzymes which use thiamine pyrophosphate (B1) as a coenzyme

pyruvate DH and transketolase

what are the metabolic roles of Coenzyme A (B5)?

acyl group transfer and C-C bond formation

example of a reaction where CoA (B5) acts as a coenzyme

… + … + … → … + … + …

pyruvate + NAD+ + CoA-SH → acetyl CoA + NADH + CO2

what is the metabolic role of pyridoxal phosphate?

amino group transfer

what is the metabolic role of biotin (B7)?

CO2 transfer to carbanion substrates

example of a reaction where biotin is used as a coenzyme to transfer a CO2?

… → … (fatty acid synthesis)

acetyl CoA carboxylase

acetyl CoA → malonyl CoA

when biotin acts as a coenzyme, it first attaches to a CO2 and then donates it to a carbanion. what is the intermediate CO2-biotin called?

carboxybiotin

another name for dTMP?

thymidylate

what is the metabolic role of tetrahydrofolate (B9)?

one carbon transfers in purine, thymidylate and methionine synthesis

what are the two main active coenzyme forms of B12?

methyl and adenosyl B12

what is the metabolic role of adenosyl B12? (adenosylcobalamin)

odd chain fatty acid and certain amino acid catabolism

what is the metabolic role of methyl B12? (methylcobalamin)

methionine synthesis

oxidative decarboxylation of pyruvate uses which vitamins as coenzymes?

pyruvate + NAD⁺ + CoA-SH → acetyl-CoA + NADH + CO₂

(answer with B#)

B1, B2, B3 and B5

in what forms are B1, B2, B3 and B5 used in the oxidative decarboxylation of pyruvate?

thiamine pyrophosphate, NAD, FAD and CoA