Protein and Amino Acid Metabolism Flashcards
what are the major nitrogen containing components in the body
- amino acids
- proteins
- nitrogenous bases
- creatine
what is creatinine
break down product of creatine and creatine phosphate
what is the level of creatinine in the urine proportional to
muscle mass
what is creatinine used as an indicator for
renal function (raised levels on damage to nephrons)
when is it normal to have a large nitrogen intake than output
during pregnancy or rapid growth
when is it normal to have a larger nitrogen output than intake
it is never normal - only occurs in trauma, infection and malnutrition
what is the main method for nitrogen output
loss of nitrogen through the faeces and urine
what is proteolysis
production of amino acids from proteins
what happens to amino acids in the liver
they are broken down into an amino group and the carbon skeleton
what are glucogenic amino acids
ones that can undergo gluconeogenesis to give energy e.g. glycine
what are ketogenic amino acids
ones that produce ketone bodies to give energy e.g. lysine and leucine
what determines whether an amino acid is glucogenic or ketogenic
their side chains
give an example of an amino acid that is both glucogenic and ketogenic
tyrosine
what effect does insulin have on protein synthesis
increases
what affect does glucocorticoids have on protein synthesis
decreases it
what is cushing’s syndrome
excessive breakdown of protein occurs weakening the skin structure leading to striae formation
what are non essential amino acids synthesised from
- intermediates of glycolysis
- pentose phosphate pathway
- krebs cycle
what is transamination
the conversion on one amino acid to another by swapping an amine group of an amino acid with an oxygen of a keto acid
what does tyrosine produce
- catecholamines
- melanin
- thyroid hormones
what does cysteine produce
- glutathione
what does histidine produce
histamine
what does arginine produce
nitric oxide