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
