nutrition

Question 1

macronutrients

Answer 1

carbohydrates, fats, proteins

Question 2

micronutrients

Answer 2

vitamins and minerals

Question 3

why are vitamins “essential”

Answer 3

because they are compounds which are necessary but the human body cannot synthesise them, therefore they must be obtained from a nutrient source

Question 4

large amounts of vitamins are required to have an effect true/false

Answer 4

FALSE small amounts only (

Question 5

vitamins are building blocks for larger molecules true false

Answer 5

false false false

Question 6

vitamins do not yield energy when broken down true false

Answer 6

true true

Question 7

how many vitamins are required in the human diet

Answer 7

12

Question 8

vitamin C and B are…

Answer 8

water soluble vitamins

Question 9

vitamin A E D and K are…

Answer 9

lipid-soluble vitamins

Question 10

features of water soluble vitamins

Answer 10

• functional uniformity
• highly variable structures
• carry mobile metabolic groups
• all require modification (except for vitamin C)
• readily excreted by the kidneys
• labile (degradable)

Question 11

Lipid soluble vitamins

Answer 11

• structural uniformity
• functionally diverse
• not as readily absorbed/extracted from food
• generally not coenzymes/ activated carriers

Question 12

vitamin A and D

Answer 12

act like hormones. toxic in excess

Question 13

why can’t humans synthesise vitamin C?

Answer 13

we don’t have the enzyme GULOLACTONE OXIDASE. the gene is present, but mutations have made it inactive. theory: the same enzyme synthesises H2O2 which is toxic

Question 14

three B vitamins to remember

Answer 14

Riboflavin (B2)
Nicotinic acid (B3)
Folic acid (B9)

Question 15

vitamin c also called…

Answer 15

ascorbate

Question 16

features of vitamin C

Answer 16

• electron donor (reducing agent / antioxidant) for 8 enzymes
• interacts with enzymes having monooxygenase or dioxygenase activity
• accelerates hydroxylation (3 enzymes)

Question 17

vitamin c deficiency

Answer 17

scurvy

Question 18

vitamin D deficiency

Answer 18

bone issue (rickets, osteomalacia)

Question 19

causes of vitamin C deficiency

Answer 19

• sailors
• elderly
• alcoholics (decreased absorption and storage)
• mentally ill
• otago uni scrubs

Question 20

amino acids making up collagen

Answer 20

every third residue = Glysine

proline and HYDROXYPROLINE are also abundant

Question 21

why is vitamin C necessary for collagen synthesis

Answer 21

• stabilisation of the triple helix (of collagen) requires HYDROXYPROLINE
• HYDROXYPROLINE requires vitamin c for synthesis
• Vitamin C reduces ferric (Fe3+) to ferrous (Fe2+)
• ferrous activates proline hydroxylase
• hydroxylase converts proline to hydroxyproline

Question 22

sources of 1 carbon units

Answer 22

Serine
formate
glycine
histidine

Question 23

end products of 1 carbon metabolism

Answer 23

methianine
eTMP
purines

Question 24

1 carbon units

Answer 24

methyl
methylene
formyl

Question 25

what are folates essential for?

Answer 25

cell growth and tissue development

Question 26

three major structural components of folic acid

Answer 26

1. bicyclic, heterocyclic, pteridine ring 2. benzoic acid (P-amino) PABA 3. Glutamic acid (folic acid = monoglutamic)

Question 27

folate to dihydrofolate to tetrahydrofolate, catalysed by...

Answer 27

dihydrofolate reductase. This is in mammals.

Question 28

antimetabolite =

Answer 28

synthetic compound, usually structurally-related to the metabolite, that interferes with the metabolite to which it is related

Question 29

how are poly-γ-glutamate tails added to tetrahydrofolate

Answer 29

addition of multiple glutamic acid residues in liver cells

Question 30

where are tetrahydrofolates largely stored

Answer 30

liver

Question 31

why are poly-γ-glutamate tails added?

Answer 31

i. helps retain THF inside cells, because it is a poor substrate for anion transporter ii. helps THF bind more tightly to enzymes - enhanced affinity

Question 32

what is the role of folate/tetrahydrofolate derivatives?

Answer 32

to transfer 1C units to N5 and N10 in THF

Question 33

carbon unit transfer is involved in... which are all important for...

Answer 33

synthesis of amino acids, purines, deoxythymine monophosphate all building blocks for RNA/DNA precursors

Question 34

inhibitors of folate synthesis inhibit... resulting in...

Answer 34

DHFR e.g. Aminopterin binds DHFR at least 1000 fold higher affinity. By blocking DHFR you will stop Production of DNA precursors. = STOP GROWTH

Question 35

inhibitors of bacterial cell growth. What are they called and what do they do, etc. ?????

Answer 35

--BACTERIOSTATIC drugs-- e.g. methotrexate - sulphonamides inhibit enzyme: DIHYDROPTEROATE

Question 36

neural tube defects

Answer 36

combination of genetic predisposition & environmental (deficient folate). = Failure of neural tube to close

Question 37

spina bifida

Answer 37

neural tube doesn't close at the caudal end

Question 38

anencephaly

Answer 38

neural tube doesn't close at the cranial end. No cerebral cortex.

Question 39

how does folate prevent neural tube defects?

Answer 39

increased methylation of various important molecules

Question 40

summary : enzyme involved with folate in bacteria _______________ enzyme involved in mammals ______________

Answer 40

summary : enzyme involved with folate in bacteria _dihydropteroate synthase_ enzyme involved in mammals _dihydrofolate reductase_