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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
What are the 2 kinds of receptors in target cells for Retinoic Acid?
RAR for all trans retinoic acid | RXR for 9 cis retinoic acid
26
What are Vitamins?
They are organic compounds that our body cannot make so we have to get in the diet
27
What compounds have Vit A activity?
1) Retinol 2) Retinal (Oxidated Retinol) 3) Retinoic Acid (Oxidates Retinal) - Limited Activity 4) Beta-Carotene which can be converted to retinal
28
What happens if we get a Thiamine deficiency?
1) Beri-beri 2) Weirnicke-Korsakoff syndrome (alcoholics) Cadiac pathology Polyneuritis Edema
29
what happens if we have a deficiency in Niacin?
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
WHat happens in the case of defficiency if Vit A?
- night blindness | - Keratinization of epithelial cells
31
WHat happens to Retinol in the Retina?
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
What happens when there is a defficiency of Roboflavin?
This is rarely observed alone bc it is widely distributed Skin lesions
33
What is associated with polyneuritis, cardiac pathology and edema?
Beri-Beri and Wernicke-Korsakoff (alcoholics | due to a lack of Thiamine
34
What is important about the reaction Retinal -> Retinoic Acid?
It is irreversible
35
What is microlytic anemia due to?
Deficiency in Vit B6 or Pyridoxine
36
WHat is Riboflavin?
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
WHat is the csq of deficiency in Pyridoxine?
- Dermatitis - Consulsions - Microlytic Anemia
38
What is the effect of Avidin?
Presentin Raw Eggs Binds tighly but not covalently to Biotin and inhibits its absorbtion -> can trigger dermatitis, nausea, anorexia and muscle pain
39
What is the funtion of VItamin A?
- Visual Cycle (Retinal) | - Maintenance of Epithelial Cells (Retinoic acid- TF)
40
WHat is the RDA?
1.7 mg/day
41
What is the recommended value for Pyridoxine?
2md/day
42
What is Thiamine?
Vit B1 Precursor for Thiamine Pyrophosphate -> coE for decarboxylation of alpha-keto acids (ex pyruvate to ACoA) and transketolases
43
WHat should I think of when I see skin lesions?
1) Riboflavin deficiency | 2) Kwashiorkor if accompanied by distended abdomen and thin limbs
44
What vitamins are in the B complex?
``` B1 B2 B3 B5 B6 B7 B9 B12 ```
45
Where can it be found?
Made by intestinal flora Liver Vegetables
46
Where can we find Pantothenic Acid?
Made by bacteria in gut | Widely Distributed
47
Where can we find Riboflavin?
Liver Milk Green vegetables
48
Where can we find Vit A?
Vegetables Fish Liver Oil (Khalo Bashir sees well) Carrots
49
Where can we get Thiamine from?
Nuts Fruits Beans
50
Where is Niacin found?
Legumes, Meat
51
Where is Vit B6 found?
Liver, fish, nuts, whole grain cereal
52
Why can't the Retinoic Acid participate in the visual cycle?
Bc it is an all trans unsaturated compound and we need 11 cis

Biochem (8 decks)

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