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Biochem > Nutrition L 53, 54 > Flashcards

Nutrition L 53, 54 Flashcards

1
Q

After digestion of Vit A, where does it go?

A

To the liver where Retinyl esters are hydrolyzed to retinol

Livers excerete Retinol as Retinol +Retinol Binding Protein which can go to peripheral cells or to the Retina

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2
Q

Biotin

A

Vit B7
Not changed
Covalently bound to Lys on E in carboxylation
Has NH end that binds to CO2 then gives it up to the Substrate

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3
Q

Conversion of beta carotene to retinal

A

B-carrotene +O2 –> 2 free Retinal

E= b-carrotene dioxygenase

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4
Q

Defficiencies of Pantothenic Acid

A

None described, widely avai.

Nausea, Fatigue

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5
Q

Defficiency in Biotin

A

Dermatitis
Anorexia
Muscle Pains
Nausea

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6
Q

Fat Soluble Vitamins:

A

A, D, E, K

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7
Q

How is FAD Made?

A

Flavin Adenine Dinucleotide
FMN + ATP -> FAD + PPi

We put AMP on FMN

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8
Q

How is FMN made?

A

Flavin Mononucleotide
Riboflavin + ATP ->FMN + ADP

we put 1 PO43- on

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9
Q

How is NAD+ made form niacin?

A

It is Niacin with AMP added on it

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10
Q

how is NADP made from Niacin?

A

Niacin s turned to NAD+

Then another PO43- is added on the 2’OH of the ribose

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11
Q

How is retinoic acid a TF

A

1) RA binds to RAR and RXR
2) RAR and RXR with ligands form dimer
3) The dimer targets the promoter of the genes
4) Transcription of these genes activated

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12
Q

How is Thiamine Turned into Thiamine Pyrophosphate?

A

Thiamine + ATP –> TPP + AMP

we add a pyrophosphate inside the cell since PPi is negatively charged and cannot cross the mb

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13
Q

how is Vit A digested?

A

We digest it either as beta-carotene or retinyl ester
Then it is broken down to retinol
In the epithelial cells, it assembles with FA CoA and go in chylomicrons as Retinyl Ester

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14
Q

How much of it is needed?

A

19 mg/day

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15
Q

How much recommended for Biotin?

A

No RDA

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16
Q

How much Thiamine is recommended

A

1.5 mg/day

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17
Q

Is excess toxic?

A

yes, it causes increased cranial pressure, headaches and could be fatal

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18
Q

NAD and NADP

A

NAD and NADP can be made from Tryp which is not an essential aa
so Trp can be made from precursors and taht can make NAD and NADP
However, these qty are not enough and that is why a deficiency in Niacin would cause Pellagra

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19
Q

Niacin or Nicotinic Acid

A

Vit B3 but it is rarely called this way

Precursor for NAD and NADPH (ox-red reactions)

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20
Q

Pantothenic Acid

A

Vitamin B5
Precursor for pantothein
-> CoA

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21
Q

RDA for Pantethonic Acid

A

Not established

5-10 mg

22
Q

RDA of Vit A

A

1000 ug of retinal- 1 mg

6000 ug of beta carrotene

23
Q

Vit B6

A

Pyridoxine
Pyridoxinamine
Pyridoxal

> > precursor for Pyridoxal Phosphate
CoE for transamination, deamination, decarboxylation and Glycogen Phosphatase (degradation of Glycogen)

24
Q

Water Soluble

A

C and B complex

25
Q

What are the 2 kinds of receptors in target cells for Retinoic Acid?

A

RAR for all trans retinoic acid

RXR for 9 cis retinoic acid

26
Q

What are Vitamins?

A

They are organic compounds that our body cannot make so we have to get in the diet

27
Q

What compounds have Vit A activity?

A

1) Retinol
2) Retinal (Oxidated Retinol)
3) Retinoic Acid (Oxidates Retinal) - Limited Activity
4) Beta-Carotene which can be converted to retinal

28
Q

What happens if we get a Thiamine deficiency?

A

1) Beri-beri
2) Weirnicke-Korsakoff syndrome (alcoholics)

Cadiac pathology
Polyneuritis
Edema

29
Q

what happens if we have a deficiency in Niacin?

A

Pellagra which is mainly a scin condition
a lack of NAD and NADP would cad 3 D
Dermatitis
Diarrhea
Dimentia
Possibly death
On steps the symptoms are not simply stated

30
Q

WHat happens in the case of defficiency if Vit A?

A
  • night blindness

- Keratinization of epithelial cells

31
Q

WHat happens to Retinol in the Retina?

A

1) Oxidized to Retinal- all trans
2) All trans retinal -> 11 cis retinal
3) 11 cis Retinal binds to opsin (Opsin +11cis retine = Rhodopsin)
4) Light converts 11 cis back to trans-cic retinal and opsin detaches
5) Trans Retinal is converted back to 11 cis and the cycle continues

32
Q

What happens when there is a defficiency of Roboflavin?

A

This is rarely observed alone bc it is widely distributed

Skin lesions

33
Q

What is associated with polyneuritis, cardiac pathology and edema?

A

Beri-Beri and Wernicke-Korsakoff (alcoholics

due to a lack of Thiamine

34
Q

What is important about the reaction Retinal -> Retinoic Acid?

A

It is irreversible

35
Q

What is microlytic anemia due to?

A

Deficiency in Vit B6 or Pyridoxine

36
Q

WHat is Riboflavin?

A

Vit B2
Precursor for FMN and FAD (usef when Fumarate is made by Succinate D and in the 1st oxidation of FA oxidation when db is made, FAD accpets the 2 H -> FADH2)

37
Q

WHat is the csq of deficiency in Pyridoxine?

A
  • Dermatitis
  • Consulsions
  • Microlytic Anemia
38
Q

What is the effect of Avidin?

A

Presentin Raw Eggs
Binds tighly but not covalently to Biotin and inhibits its absorbtion

-> can trigger dermatitis, nausea, anorexia and muscle pain

39
Q

What is the funtion of VItamin A?

A
  • Visual Cycle (Retinal)

- Maintenance of Epithelial Cells (Retinoic acid- TF)

40
Q

WHat is the RDA?

A

1.7 mg/day

41
Q

What is the recommended value for Pyridoxine?

A

2md/day

42
Q

What is Thiamine?

A

Vit B1
Precursor for Thiamine Pyrophosphate -> coE for decarboxylation of alpha-keto acids (ex pyruvate to ACoA) and transketolases

43
Q

WHat should I think of when I see skin lesions?

A

1) Riboflavin deficiency

2) Kwashiorkor if accompanied by distended abdomen and thin limbs

44
Q

What vitamins are in the B complex?

A 
B1
B2
B3
B5
B6
B7
B9
B12
45
Q

Where can it be found?

A

Made by intestinal flora
Liver
Vegetables

46
Q

Where can we find Pantothenic Acid?

A

Made by bacteria in gut

Widely Distributed

47
Q

Where can we find Riboflavin?

A

Liver
Milk
Green vegetables

48
Q

Where can we find Vit A?

A

Vegetables
Fish Liver Oil (Khalo Bashir sees well)
Carrots

49
Q

Where can we get Thiamine from?

A

Nuts
Fruits
Beans

50
Q

Where is Niacin found?

A

Legumes, Meat

51
Q

Where is Vit B6 found?

A

Liver, fish, nuts, whole grain cereal

52
Q

Why can’t the Retinoic Acid participate in the visual cycle?

A

Bc it is an all trans unsaturated compound and we need 11 cis

Biochem (8 decks)

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