transanimation

Question 1

what happens in amino acid metabolism

Answer 1

excess ammonia generated in extrahepatic tissues by catabolism of amino acids and nucleic acids
transported in the bloodstream amino groups to the liver where they are converted to urea for excretion

Question 2

what transports amino groups generated in muscle

Answer 2

alanine

Question 3

what degraded amino acids

Answer 3

muscle

Question 4

what are amino groups collected as

Answer 4

glutamate

Question 5

what is glutamate converted to

Answer 5

alanine by action of alanine aminotransferase

Question 6

how does alanine take amino groups to the liver

Answer 6

via the bloodstream

Question 7

where does alanine aminotransferase convert alanine to glutamate

Answer 7

cytosol of hepatocytes

Question 8

what releases NH4 and where

Answer 8

glutamate dehydrogenase into the mitochondria

Question 9

what is the role of glutamine

Answer 9

transports ammonia in the blood to the liver where processed for excretion

Question 10

what happens to glutamine

Answer 10

in the mitochondria, glutaminase converts it to glutamate with the release of NH4

Question 11

what happens to NH4

Answer 11

directly excreted - forms salt with metabolic acids attempt to counteract acidosis

Question 12

what happens in the cytosol of hepatocytes in transanimation

Answer 12

amino groups form L-amino acids are transferred onto a-ketoglutarate to form glutamate
the amino acid becomes the corresponding a-ketoacid

Question 13

what is the transamination reaction catalyzed by

Answer 13

specific transaminases (aminotransferases)

Question 14

what happens to glutamate

Answer 14

transported to the mitochondria of hepatocytes, where the amino group is removed to form NH4+

Question 15

what is transamination dependent on

Answer 15

the transaminase cofactor, pyridoxal phosphate

Question 16

what is pyridoxal phosphate

Answer 16

an intermediate carrier of amino groups between amino acid and enzyme

Question 17

what does pyridoxal phosphate do

Answer 17

accepts amino group from amino acid amd donates amino group to a-ketoglutarate

Question 18

what is the role of transamination reactions

Answer 18

collect amino group from amino acids in the form of L-glutamate

Question 19

what pathways do glutamate act as an amino donor in

Answer 19

biosynthetic pathways and excretion pathways

Question 20

how is the excretion of amino acids done

Answer 20

glutamate is transported to the mitochondria where glutamate dehydrogenase removes amino group in an oxidative deamination reaction with the formation of a-ketoglutarate and NH4+

Question 21

what is used in the excretion of amino acids

Answer 21

NAD+ or NADP+, which are reduced to NADH and NADPH