MEH - Protein/Amino Acid Metabolism Flashcards Preview

CJ: UoL Medicine Semester Two (ESA2) > MEH - Protein/Amino Acid Metabolism > Flashcards

Flashcards in MEH - Protein/Amino Acid Metabolism Deck (50)
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1

Give some examples of nitrogen containing compounds in the human body

- amino acids
- proteins
- purines/pyrimidines
- porphyrins
- creatine
- neurotransmitters
- some hormones

2

What is creatinine?

A breakdown product of creatine and creatine phosphate in the muscle

3

How is creatinine excreted?

Filtered via kidneys into urine. For men, 14-26 mg/kg per day. For women, 11-20 mg/kg per day

4

What can creatinine be used to measure?

Creatinine urine excretion over 24h is proportional to muscle mass, so it can be used to estimate it. Also often used as indicator of renal functions (raised when nephrons are damaged)

5

What does it indicate if a person has a 'positive nitrogen balance'?

Intake is larger than output, so there is an increase in total body protein. Person may be growing, pregnant or recovering from malnutrition

6

What does a negative nitrogen balance indicate?

Intake is lower than output, so there is a net loss of body protein. Causes include trauma, infection or malnutrition

7

What does it mean if the body is at nitrogen equilibrium?

No change in total body protein - normal state in adult

8

What do glucogenic amino acids undergo in the body?

Gluconeogenesis

9

What do ketogenic amino acids undergo in the body?

Ketone bodies

10

Give an example of a glucogenic amino acid

Alanine, glycine, cysteine, serine, arginine, proline, histidine, glutamine, glutamate, methionine, valine, aspartate, asparagine,

11

Give an example of ketogenic amino acids

Lysine, leucine

12

Give some examples of amino acids that are both glucogenic and ketogenic

Tryptophan, tyrosine, phenylalanine, threonine, isoleucine

13

What is the effect of insulin and growth hormone on protein synthesis/degradation?

- increases protein synthesis
- decreased protein degradation

14

What is the effect of glucocorticoids on protein synthesis?

- protein synthesis decreases
- protein degradation increases

15

Why is it important for a vegetarian diet to contain proteins from a wide variety of plant sources?

Proteins of plant origin are generally considered lower quality as most are deficient in one or more essential amino acids

16

What are the nine essential amino acids? (Mnemonic - if learned this huge list may prove truly valuable)

Isoleucine, lysine, threonine, histidine, leucine, methionine, phenylalanine, tryptophan, valine

17

Where does the body obtain the carbon atoms it requires for non-essential amino acid synthesis?

- intermediates of glycolysis
- pentose phosphate pathway
- Krebs cycle

18

Where does the body obtain the amino group for non-essential amino acid synthesis?

It is provided by other amino acids by the process of transamination or from ammonia

19

What is tyrosine used to synthesise?

Catecholamines, melanin, thyroid hormones

20

What is cysteine used to synthesise?

Hydrogen sulphide, glutathione

21

What is tryptophan used to synthesise?

Nicotinamide, serotonin, melatonin

22

What is histidine used to synthesise?

Histamine

23

What is glutamate used to synthesise?

GABA

24

What is glycine used to synthesise?

Purines, glutathione, haem, creatine

25

What is arginine used to synthesise?

Nitric oxide

26

What is serine used to synthesise?

Sphingosine

27

What is transamination?

Swapping the amine group of an amino acid with the oxygen of a keto acid

28

What are the two main aminotransferase enzymes?

Alanine aminotransferase (ALT - converts alanine to glutamate)
Aspartate aminotransferase (AST - converts glutamate to aspartate)

29

Give some examples of conditions that may cause high plasma ALT and AST levels

- viral hepatitis
- autoimmune liver diseases
- toxic injury

30

What is deamination?

The liberation of an amino group as free ammonia, which mainly occurs in the liver and kidney. The ammonia is very toxic so it is removed by conversion to urea or being excreted in the urine.

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