Protein Metabolism Flashcards
how does the recommended protein intake change over time
decreases with age
but increased if athlete or breastfeeding
what are essential amino acids
ones which cannot be synthesised within the body so must be supplied in the diet
what are non-essential amino acids
ones which can be synthesised from other amino acids in the diet
what are semiessential amino acids
ones which can be synthesised by not in enough quantity
what should your protein intake be like and why
varied
different proteins have different amino acids
what are two presentations of protein malnutrition
kwashiorkor - abdo bloating caused by liver
marasmus
what is the difference in cause of kwashiorkor and marasmus
kwashiorkor - adequate energy intake but inadequate protein intake
marasmus - inadequate protein and energy intake
treatment of kwashiorkor
aminio acid supplements
what is urea
waste product of amino acidsa
what is nitrogen balance
intake of nitrogen-excretion of nitrogen
causes of positive nitrogen balance
pregnancy
growth
causes of negative nitrogen balance
protein deprivation
AA deficiency
trauma
disease
what is there a negative nitrogen balance in AA defficiency
protein production stops but break down continues so more urea produced = loss of nitrogen
how are circulating proteins broken down
extracellular proteins accumulate damage
endocytosis occurs
lysosome enzymes degrade protein
where does protein digestion begin
stomach
describe secretion of pepsin and where this happens
acetylcholine triggers secretion of pepsinogen which is a precusor
pepsinogen is activated to pepsin
this happens in chief cells
what effect does pepsin have on proteins
breaks them down into peptide chains not all the way down to amino acids
describe activation of pancreatic zymogens
tripsinogen is activated by enteropeptidase to trypsin
trypsin self catalyses activation of trypsinogen and the other zymogens
what is the safety catch of activation of pancreatic zymogens and how does this work
trypsin inhibitor
need lots of trypsin to overpower the inhibitor and cause activation of zymogens
what is the urea cycle
forms urea from amino acids
is urea water soluble
yes very
is urea acidic or basic or neutral
neutral
where is urea synthesised
liver
when does plasma urea levels rise
renal failure
when does plasma urea fall
liver cirrhosis
when does plasma urea fall and what rises as a result
liver cirrhosis as cant produce urea so ammonia rises
why does liver failure cause encephalopathy
urea can’t be made
so ammonia rises
which is toxic to CNS
how are amino groups transported from tissue to the liver
as alanine
what happens to alanine in starvation
it increases
what antibiotic inhibits synthesis of folic acid in bacteria
sulphonamide
what drug is a derivative of folic acid
methotrexate
