amino acids brought in by digestion - go to liver - carbon to glucose of TAGs to liver - hepatic portal - as single AAs in blood stream

Biochem CIS Flashcards by Matt Stanton

in bloodstream

single amino acids

then transpored into cells

How well did you know this?

Not at all

Perfectly

amino acid metabolism

need to excrete nitrogen - urea

carbon as energy

How well did you know this?

Not at all

Perfectly

urea

from urea cycle in liver

How well did you know this?

Not at all

Perfectly

uric acid

from purine bases

How well did you know this?

Not at all

Perfectly

creatinine

from creatine phosphate

How well did you know this?

Not at all

Perfectly

ammonia

from glutamine in kidney

How well did you know this?

Not at all

Perfectly

bilirubin

from heme

How well did you know this?

Not at all

Perfectly

nitrogen to be excreted

urea
uric acid
creatinine
ammonia
bilirubin

How well did you know this?

Not at all

Perfectly

fed state

amino acids brought in by digestion

go to liver
carbon to glucose of TAGs

to liver - hepatic portal - as single AAs in blood stream

How well did you know this?

Not at all

Perfectly

fasting state

amino acids released from protein breakdown

release single AAs from proteins in body - major source muscle

shuttles in blood - carrier AAs - glutamine and alanine**

How well did you know this?

Not at all

Perfectly

albumin

created by liver

-one of main uses of amino acid nitrogen in the liver

How well did you know this?

Not at all

Perfectly

glutamine

transport of nitrogen to kidney

ammonia

How well did you know this?

Not at all

Perfectly

alanine

transport of AAs to liver

for urea

How well did you know this?

Not at all

Perfectly

case - 21yo M, loss of appetitive, N/V, joint pain, abdomen pain, ice tea colored urine, clay colored stool, caribbean travel recent, jaundice, enlarged and tender liver

ALT and AST very high
alk phos high
bilirubin high
positive IgM anti-HAV

sent home

6 weeks later, vomiting, jerking, grimacing, altered LOC, ALT, AST, alk phos, bilirubin increased - admitted to hosp

travel - hepatitis A - from food

sent home - no real tx for Hep A

avoid tylenol - acetaminophen hepatotoxic

at 6 weeks - see necrosis with acetaminophen and the hepatitis
-hyperammonemia

How well did you know this?

Not at all

Perfectly

hyperammonemia

caused by liver failure - or hepatotoxicity due to inflammation

sx - brain swelling - osmotic imbalance

How well did you know this?

Not at all

Perfectly

high ammonia in brain

alters osmotic balance - causes brain swelling

How well did you know this?

Not at all

Perfectly

high ammonia and glutamate in astrocytes

initiates glutamine synthetase and inhibits glutaminase

astrocytes produce glutamine

How well did you know this?

Not at all

Perfectly

glutamate

central to urea production
-provides nitrogens for urea cycle

one from ammonium ion

one from aspartate

How well did you know this?

Not at all

Perfectly

transamination rxn

transfer of nitrogen in form

convert amino acid to its alpha-keto acid

is reversible

How well did you know this?

Not at all

Perfectly

glutamate

produced from alpha-ketoglutarate + any other AA

steal N from AA

glutamate transfers N to other molecule via second transamination
-if to oxaloacetate - to make aspartate

How well did you know this?

Not at all

Perfectly

alpha-keto acid of aspartate

oxaoacetate

How well did you know this?

Not at all

Perfectly

glutamate

for transamination rxn

How well did you know this?

Not at all

Perfectly

nitrogen carriers

alanine

glutamine

How well did you know this?

Not at all

Perfectly

alanine

specific to muscle
-pyruvate** transaminated to alanine

alanine then to liver

How well did you know this?

Not at all

Perfectly

glutamine

in liver, muscle, somatic cells | -from glutamate

glutamine

is one more nitrogen to glutamate alpha-KG - 0 N glutamate - 1 N gultamine - 2 Ns

urea cycle

in liver -nitrogen source - ammonium or aspartate in mito - carbmoyl phosphate from free ammonium ion - react with ornithine -produce cirtuline - crosses mito membrane to cytosol in cytosol - aspartate plus citrulline to arginossuccinate - produce agrinine - release urea and regenerate ornithine

low blood cirtulline

defect in carbamoyl phosphate synthetase and ornithine transcarbamoylase

low blood arginine and high cirtulline

defect in arginosuccinate synthetase or arginosuccinate lyase

high blood arginine and high cirtulline

arginase defect

orotate

produced from excess carbamoyl phosphate | -with ornithine transcarbamoyl phosphate accumulation

carbamoyl phosphate

created in mito to allow ammonia to enter urea cycle will build up - with ornithine transcarbamoyl deficiency results in orotate increase**

orotate

defect in ornithine transcarbamoylase

Case - 12yo male sudden seizure, left side weakness, PMH special eduation group, surgery for downward lens dislocation of eyes CAT scan - small infarction - right cerebral hemisphere 3 days - left sided weakness cleared osteopenia, waddling gait, increased length of long bones and scoliosis high methionine no cystine elevated homocystine and homocysteine normal B12 and folate 24 hour urine homocystine elevated

probably congenital defect in pathway to form cystine homocystinuruia

homocystinuria

auto recessive deficient in cystathione synthase CV disease and developmental anomalies, mental retardation marfanoid habitus - says not vit deficienct - probably not that chronic

no cystine, elevated methioneine, elevated homocysteine

homocystinuria defect in cystathione synthase

methionine and cystine

has sulfur methionine - essential AA

B12 and folate

for homocysteine methyltransferase - homocysteine** to methionine defect - see low methionine and high homocysteine

PLP

pyrodoxal phosphate | -activated vit B6

cystathione beta-synthetase

requires PLP - vit B6 homocysteine** to cystathione

degradation of AAs

glucogenic - to glucose - intermediates of TCA cycle - all the non-essential AAs ketogenic - to ketone bodies -acetyl-CoA and acetoacetate

lysine and leucine

strictly ketogenic**

positive nitrogen balance

growth incorporated exceeds excreted

negative nitrogen balance

malnutrition excreted exceeds incorporated

Case 24 month old to clinic, Uganda, edema, distended abdomen, hypopigmented hair, dry skin given oral rehydration for 12 hours given infant formula and MTVs

malnutrition kwashiorkor

marasmus

total calorie reduction low weight, loss of body fat and muscle

kwashiorkor

protein malnutrition adequate calorie - but protein deprivation normal body weight child has edema

arginine

only essential AA during period of growth not in adults

non-essential AAs

from glucose tyrosine from phenylalanine

tx of homocystinuria

PLP - vit B6 required for transamination rxns

methionine synthesis

vit B12 and folate

Case 47yo M to ED, alcoholic, binging without eating, slurred speech, sweating, HR 110, grand mal seizure blood glucose - low blood ethanol - elevated

alcoholic hypoglycemia metabolism of alcohol - rapid to acetaldehyde - to acetate -requires NAD+ NAD + is also required for gluconeogenesis - so this cannot occur with lots of ethanol

alcoholic hypoglycemia

metabolism of alcohol utilizes NAD+ no gluconeogenesis can occur - bc also requires NAD+ occurs with increased NADH/NAD+ ratio

maintenance of blood glucose levels

by liver -glycogenolysis - fasting - 12 hours -gluconeogenesis - starvation - only source after 24 hours of fasting

gluconeogenesis and glycolysis

most steps are reverse of one another precursors lactate, alanine, glycerol 3 P

lactate

oxidized to pyruvate from anaerobic glycolysis

alanine

converted to pyruvate alanine aminotransferase from breakdown of proteins

glycerol 3 P

oxidized to DHAP by glycerol 3 P DH from FAs - adipose tissue

irreversible steps in glycolysis

4 rxns PEP to pyruvate - OAA reduced to malate - requires NAD+ one more? fructose 1,6 hisphosphatase glucose 6 phosphatase

glucose 6 phosphatase

only in liver - so only place for gluconeogenesis converts glucose to enter bloodstream

alpha 1, 6 bonds

branching of glycogen