Protein Metabolism

Question 1

how does the recommended protein intake change over time

Answer 1

decreases with age
but increased if athlete or breastfeeding

Question 2

what are essential amino acids

Answer 2

ones which cannot be synthesised within the body so must be supplied in the diet

Question 3

what are non-essential amino acids

Answer 3

ones which can be synthesised from other amino acids in the diet

Question 4

what are semiessential amino acids

Answer 4

ones which can be synthesised by not in enough quantity

Question 5

what should your protein intake be like and why

Answer 5

varied
different proteins have different amino acids

Question 6

what are two presentations of protein malnutrition

Answer 6

kwashiorkor - abdo bloating caused by liver
marasmus

Question 7

what is the difference in cause of kwashiorkor and marasmus

Answer 7

kwashiorkor - adequate energy intake but inadequate protein intake
marasmus - inadequate protein and energy intake

Question 8

treatment of kwashiorkor

Answer 8

aminio acid supplements

Question 9

what is urea

Answer 9

waste product of amino acidsa

Question 10

what is nitrogen balance

Answer 10

intake of nitrogen-excretion of nitrogen

Question 11

causes of positive nitrogen balance

Answer 11

pregnancy
growth

Question 12

causes of negative nitrogen balance

Answer 12

protein deprivation
AA deficiency
trauma
disease

Question 13

what is there a negative nitrogen balance in AA defficiency

Answer 13

protein production stops but break down continues so more urea produced = loss of nitrogen

Question 14

how are circulating proteins broken down

Answer 14

extracellular proteins accumulate damage
endocytosis occurs
lysosome enzymes degrade protein

Question 15

where does protein digestion begin

Answer 15

stomach

Question 16

describe secretion of pepsin and where this happens

Answer 16

acetylcholine triggers secretion of pepsinogen which is a precusor
pepsinogen is activated to pepsin

this happens in chief cells

Question 17

what effect does pepsin have on proteins

Answer 17

breaks them down into peptide chains not all the way down to amino acids

Question 18

describe activation of pancreatic zymogens

Answer 18

tripsinogen is activated by enteropeptidase to trypsin
trypsin self catalyses activation of trypsinogen and the other zymogens

Question 19

what is the safety catch of activation of pancreatic zymogens and how does this work

Answer 19

trypsin inhibitor
need lots of trypsin to overpower the inhibitor and cause activation of zymogens

Question 20

what is the urea cycle

Answer 20

forms urea from amino acids

Question 21

is urea water soluble

Answer 21

yes very

Question 22

is urea acidic or basic or neutral

Answer 22

neutral

Question 23

where is urea synthesised

Answer 23

liver

Question 24

when does plasma urea levels rise

Answer 24

renal failure

Question 25

when does plasma urea fall

Answer 25

liver cirrhosis

Question 26

when does plasma urea fall and what rises as a result

Answer 26

liver cirrhosis as cant produce urea so ammonia rises

Question 27

why does liver failure cause encephalopathy

Answer 27

urea can’t be made
so ammonia rises
which is toxic to CNS

Question 28

how are amino groups transported from tissue to the liver

Answer 28

as alanine

Question 29

what happens to alanine in starvation

Answer 29

it increases

Question 30

what antibiotic inhibits synthesis of folic acid in bacteria

Answer 30

sulphonamide

Question 31

what drug is a derivative of folic acid

Answer 31

methotrexate