10/5 metabolism, amino acids and urea

Question 1

where does the pool of free amino acids come from in the body?

Answer 1

body proteins; dietary proteins; synthesized nonessential amino acids.

Question 2

what takes away from our pool of amino acids in the body?

Answer 2

body proteins -or- synthesis of porphyrins, creatine, neurotransmitters, nucleotides, etc. -or- metabolize them to make energy and CO2 and urea. This would make glucose, glycogen, or ketone bodies, fatty acids, and steroids.

Question 3

what do we mean by nitrogen balance?

Answer 3

nitrogen intake is about equal to nitrogen loss

Question 4

what is the general structure of urea

Answer 4

one carbon with oxygen double bound to it and then carbon bound to two amonia

Question 5

why do we have to make urea?

Answer 5

NH4+ is toxic! and it can’t be allowed in the body, so the liver takes it and combines it into a coboxyl and makes Urea

Question 6

is tyrosine an essential amino acid?

Answer 6

It can be made from phenylalanine

Question 7

what disease will be cased by an phenylalanine hydroxylase genetic disorder?

Answer 7

PKU – inability to make tyrosine from phenylalanine

Question 8

why would phenylalanine and tyrosine be both glucogenic and ketogenic

Answer 8

they can lead to the production of oxaloacatate, and therefore, to the production of glucose, or they can lead to acetoacetate

Question 9

what happens to the nitrogen when we catabolize or metabolize amino acids

Answer 9

it gets stuck onto things to transport it. specifically it would get stuck on to alpha ketoglutarate, to make glutamate to make glutamine and then sent around the body in the blood.

Question 10

what does a transamerase do?

Answer 10

It transfers a amino group from an amino acid to an alpha-ketoglutarate to give glutamate

Question 11

what is the abreviation of Amlamine transamerase

Answer 11

ALT

Question 12

what would elevated levels of ALT mean?

Answer 12

it would indicate tissue damage !

Question 13

glutaminase would do what reaction?

Answer 13

the reverse of glutamine synthetase: to take glutamine and make glutamate.

Question 14

what would take glutamate and make glutamine by adding a NH3 group?

Answer 14

glutamine synthetase helps to detoxify ammonia that is not yet converted to urea

Question 15

The basic flow of nitrogen in amino acid catabolism:

Answer 15

–AA from Muscle; –Make Pyruvate or Oxaloacetate and generate Alpha-ketoglutarte; leads to NH4+ that will be fed into the urea cycle; –Bacteria = NH3 to the liver –Urea cycle in liver takes amonium and gives Urea –Urea as Blood Urea Nitrogen (BUN) goes to Kidney –Kidney excretes as urine

Question 16

why would glutamine synthetase be most expressed at the end of the hepatic venulle just before the terminal vein? (zone three)

Answer 16

becasue the creation of glutamine is a last ditch effort to trap the toxic NH3 (amonia) that hasn’t been processed to urea before it gets into the circulation.

Question 17

why would glutaminase be most likely expressed in hepatocytes located near the hepatic triage? (zone one)

Answer 17

because glutaminase is releaseing the amonia for the urea cycle.

Question 18

what would happen to ammonium, glutamine, and BUN (blood urea nitrogen) if difficient in the urea cycle?

Answer 18

ammonium up, glutamine up, and BUN down

Question 19

what is the general cycle of the urea cycle?

Answer 19

ornithine (an A.A.) in the mitochondria binds with an amonia (make citruline), go to cytosol, gain aspartate, lose fumarate (aspartate w/o amine) produce urea and ornithine again…

Question 20

where do proteins fit into the overview of catabolic metabolism?

Answer 20

Question 21

what are the key players in nitrogen acceptance (transport)

Answer 21

Alpha ketoglutarate that accepts an amine to become glutamate (accomplished by a transamerase), then glutamate can accept an amine to become glutamine (accomplished by glutamin synthetase).

Question 22

what are the key players in nitrogen exchange from proteins to lead into the TCA cycle or into gluconeogenisis

Answer 22

Alanine can become pyruvate (accomplished by a transaminase transfer to glutamate); Aspartate can become Oxaloacetate (accomplished again by making glutamate).

Question 23

Can be elevated and lead to pyrimidine nucleotides if urea cycle is deficient

Answer 23

orotic acid

Question 24

what does the presence of AST/ALT in the blood tell us?

Answer 24

cell damage, these are transamerases that are cytosolic ezymes and shouldn’t be in blood.

Question 25

Swap amino groups between metabolites and play key roles in amino acid synthesis and catabolism

Answer 25

transaminases

Question 26

what is the fate of protien in the body?

Answer 26

no storage of protien, so break down muscle and take it in food, make new proteins or send the carbons to glycolytic or TCA paths and the nitrogen to urea

Question 27

who is likely to be in positive nitrogen balance?

Answer 27

growing kids, pregnant women and convalescing adults.

Question 28

what leads to positive nitrogen balance?

Answer 28

a net increase in body protein stores!

Question 29

what leads to negative nitrogen balance?

Answer 29

Truama; illness = need for protien that is not being eaten; Just not eating enough protien; lack of an essential amino acid.

Question 30

disease caused by inadequate intake of both protein and energy – severe tissue wasting

Answer 30

Marasmus

Question 31

inadequate intake of protein and adequate energy intake

Answer 31

Kwashiorkor disease

Question 32

what could cause Kwashiorkor disease?

Answer 32

infection or other that leads to catabolic state

Question 33

why a swollen belly with kwashiorkor

Answer 33

edima because the belly can’t secrete enough serum protien to maintain osmolarity!

Question 34

what transaminase can take alanine and make pyruvate?

Answer 34

Alanine Transaminase (ALT); It uses alpha-ketoglutarate and puts the amine group on it to make glutamate

Question 35

what transaminase can take aspartate and make oxaloacateate?

Answer 35

Aspartate transaminase (AST) using Alpha-ketoglutarate and making glutamate as well