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122 Cards in this Set

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What do the majority of the amino acids in the pool going into making?
proteins
What are the two characteristics of protein quality and what are two examples of foods that have good protein quality?
1) the proteins that you are taking in are easily digestable
2) have a good spectrum of all the amino acids you need for your well being
Examples are eggs and milk
Where is the largest portion of protein used in the body?
skeletal muscle
What will put you into a negative nitrogen balance?
1) inadequate dietary protein
2) absence of an essential amion acid
3) trauma
What are the initial stages of protein digestion in the stomach?
Stretch reflexes in the stomach involved the release of gastrin and this stimulates the secretion of acid from the parietal cells and pepsinogen from the cheif cells. The low pH converts pepsinogen into pepsin which is used for digestion of proteins.
What is the process of digestion in the pancreas?
The pancreas, as an exocrine function, secretes enzymes in the form of zymogens that become active proteases in the intestine, that will break proteins down to individual amino acids that can be absorbed into the sodium dependent amino acid transfer systems located in the cells that make up the microvilli
How do the exocrine cells of the pancreas store enzymes?
As zymogens
How do the zymogens protect themselves from activation?
1) trypsinogen has a site for the PSTI that keeps it from spontaneously activating
2) trypsin can bind to itself and destroy itself
What is the defect in familial pancreatitis?
There is a substitution of arg 117 to his 117 and when this happens the trypsin lose the ability to fold upon themselves and destroy each other
How are the broken down aa taken up into the villi?
By a sodium/amino acid symporter
What are the two major mechanisms for protein turnover?
1) Lysosomal pathway
2) Ubiquitin proteosome pathway
How does the epstein barr virus have an effect?
It guides the RB to the ubiquitin proteosome pathway
What does the lysosomal pathway destroy?
Larger structures
extracelluarl matrix
plasma proteins
What does the ubiquitin proteosome pathway destroy?
organelles
cytoskeleton
cytosol proteins
What protects against neuronal cell death?
Autophagy
What are inside fibrous inclusions?
Ubiquitinated proteosomes that could not be processed by the ubiquitin proteosome pathway
When an amino acid is catalyzed, what are the two parts?
A keto acid which is everything minus the amino group and the amino group
What are the N containing molecules that we incorporate the NH4 into?
1) glutamate/glutamine
2) amino acids and special products
3) N containing metabolites
4) urea
What is the starting point for the metabolism of an amino acid?
A transamination reaction
Where is the amino group added from the transamination and what does it make?
It is added to the alpha keto glutarate and makes glutamate
What becomes an amino acid donor for non-essential amino acid synthesis?
Glutamate
What is the cofactor in aminotransferases?
Pyridoxal-5-phosphate (PLP)
What are the products of a transamination?
alpha keto acid and a glutamate
What happens to the alpha keto acid after the transamination reaction?
It can be oxidized to get ATP or the carbon skeleton can be used in biosynthesis
What happens to the glutamate after the transamination reaction?
It can donate the NH4 to many NH4 requiring biosynthetic pathways and or to the urea cycle for nitrogen excretion and or the formation of glutamine which is also an important nitrogen containing compound
What is the enzyme that adds another nitrogen onto glutamate to make glutamine?
Glutamine synthetase which is an ATP requiring enzyme
Which enzyme turns gluatmine back into glutamate?
Glutaminase
Which enzyme turns glutamate back into alpha ketogluterate?
Glutamate dehydrogenase
What are the two functions of glutamine?
1) protect cell from free NH4
2) feed the TCA by making alpha ketoglutarate
Which amino acids are most likely to make ketone bodies?
those that can make acetyl coA or acetoacytyl coA
Which amino acids are probably going to be glucogenic?
Those that can make oxalacetate
What are the branched chain amino acids?
Isoleucine, leucine, and valine
Which tissue are the branched chain amino acids most essential to?
muscle
Which amino acid does muscle mostly secrete?
alanine
Which tissues oxidize branched chain amino acids?
muscle, kidney, heart, adipose, brain, and liver
What two things do branched chain amino acids provide?
ketones and succinyl coA
What can't the patients with maple syrup urine disease do?
They can't metabolize branched chain aa
What two enzymes do you need for the catabolism of branched chain amino acids?
aminotransferase and alpha keto acid dehydrogenase
Which enzyme is deficient in maple syrup urine diesase?
alpha keto acid dehydrogenase
What are the benefits of ammonia?
1) Non essential amino acid synthesis
2) purine synthesis
3) pyrimidine synthesis
4) amino sugars
5) special products
6) pH regulation (kidney)
How is ammonia toxicity prevented?
1) excretion as NH4
2) excretion as urea
3) incorporation in N containing molecules
What are the four ways ammonia leaves the tissues to travel to the liver?
1) free ammonia
2) glutamine
3) alanine
4) citrulline/argnine
What is the rate limiting enzyme in the urea cycle?
carbamoyl phosphate synthetase
Where does the second ammonia come from in the urea cycle?
aspartate
What are the substrates for the rate limiting enzyme of the urea cycle?
NH4 and CO2 and it uses ATP
What takes us from the mitochondria to the cytosol in the urea cycle?
The production of citrulline
What breaks off the urea in the urea cycle, what is it broken off of, and what is made?
1) argninase
2) arginine
3) ornithine
What is the principal regulator of the urea cycle, acting on cps I?
n-acetylglutamate
What causes water to flow into an astrocyte?
An accumulation of glutamine
What preceeds the pathology in hyperammonemia?
astrocyte swelling
What is an indicator of a coming urea cycle defect crisis?
high glutamine levels
What can be a problem in growth retardation in infants?
Low protein diets
What do you give to treat a urea cycle defect?
1) phenylbutyrate
2) benzoate
3) arginine
What does phenylbutyrate do?
Binds glutamine and excretes it
Why do you give argnine to people with argninosuccinate lyase deficiency?
To supply plenty of ornithine to replace that which was lost by argninosuccinate excretion
What are the five biosynthetic products from amino acids?
1) non essential amino acids
2) proteins
3) nucleosides
4) special products
5) glucose and amino sugars
Where do we get essential ammino acids from?
1) diet
Where do we get non-essential amino acids from?
1) glycolysis
2) tca cycle
3) essential amino acids
What does methionine make and what does phenylalanine make?
1) cysteine
2) tyrosine
What does alpha ketoglutarate make?
glutamine, glutamate, and proline
What does oxaloacetate make?
aspartate and asparagine
What does 3-phosphoglycerate make?
serine and glycine
What does pyruvate make?
alanine
What is the key reaction in non essential amino acid synthesis?
Transamination
What enzyme transaminates pyruvate to make alanine?
alanine aminotransferase
What are the two aspects of transamination of pyruvate?
1) removal of ammonia from branched chain amino acids
2) then adds that to the pyruvate to make alanine
What are the two enzymes that are part converting pyruvate to alanine?
1) branched chain aminotransferase
2) alanine aminotransferase
What serves as a carrier of ammonia equivalents and of carbon skeleton of pyruvate from muscle to liver?
alanine
What is exreted and what is used to produce glucose which is used ot maintain euglycemia especially in the fasting state in the alanine cycle?
The ammonia is excreted and the pyruvate is used to produce glucose.
What are the special products?
1) Neurotransmitters
2) Neurohormones
3) Hormones and growth factors
4) S-adenosylmethionine
5) Glutathione
6) Carnitine
7) Creatine
8) Porphyrins
9) And others
What is a key methyl group donor involved in one carbon metabolism?
S-adensylmethione
What is S-adensylmethione formed from?
methionine and an atp
What is S-adensylmethione used to form?
1) Catecholamines
2) creatine
3) carnitine
4) cysteine
5) choline
6) spermidine
7) DNA methylation
8) RNA methylation
What is exreted and what is used to produce glucose which is used ot maintain euglycemia especially in the fasting state in the alanine cycle?
The ammonia is excreted and the pyruvate is used to produce glucose.
What are the special products?
1) Neurotransmitters
2) Neurohormones
3) Hormones and growth factors
4) S-adenosylmethionine
5) Glutathione
6) Carnitine
7) Creatine
8) Porphyrins
9) And others
What is a key methyl group donor involved in one carbon metabolism?
S-adensylmethione
What is S-adensylmethione formed from?
methionine and an atp
What is S-adensylmethione used to form?
1) Catecholamines
2) creatine
3) carnitine
4) cysteine
5) choline
6) spermidine
7) DNA methylation
8) RNA methylation
What is carnitine involved in?
1) the transport of fatty acid coA into the mitochondria
2) the transport of acetyl coA between the mitochondria and the cytosol
3) the detoxification of acyl coA intermediates
What amino acid does carnitine come from?
Lysine
What are the three characteristics of glutathione?
1) found in all cells in high concentration
2) redox function, protein SH groups
3) removal of toxic peroxides
What three amino acids are part of glutathione?
1) glu
2) cys
3) gly
all atp requiring enzymes
What does glutathione peroxidase need?
It requires reduced glutathione that turns into NADPH
What else can glutathione be used for, especially with acetaminophen?
It can be used as a conjugated molecule to get rid of toxic things
What do you treat GS deficiency with?
1) free radical scavengers
2) avoid drugs that might precipitate a hemolytic crisis
What is creatine used for?
1) a high energy phosphate reservoir
2) keep atp levels stable
What does creatine come from?
Glycine and arginine and methyl donor SAM
What is renal function measured as?
a function of creatine
Which enzyme makes creatine phosphate when atp is high?
Creatine kinase
What makes epinephrine and norepinephrine?
Phenylalanine which makes tyrosine which then makes these neurotransmitters
Which amino acid makes NO?
arginine
What is the rate limiting enzyme in catecholamine synthesis?
tyrosine hydroxylase
What are the four PKU mutations?
1) null
2) kinetic
3) stability
4) cofactor
What is No used for?
1) immune mediator
2) smooth muscle relaxing factor
3) neuronal messenger
What is the enzyme for NO?
NOS called nitric oxide synthase
What does NOS do?
1) it activates guanyl cyclas which produces cGMP which activates myosin LC phosphatase which takes a phosphate off the light chains
What does cytokine mediated induction of NO do?
It decreases systemic vascular resistance and this arterial vasodilation predisposes to acute renal failure in spesis
Where does heme biosynthesis occur?
In all cells but the majors are bone marror where hemoglobin is made and liver where cytochrome p450 is made
What are the purol rings linked together by in the tetrapurol?
mytheline bridges
What is myoglobin and hemoglobin for?
carrying o2 and 70-80 percent of heme goes into this
What is catalase for?
major in the liver in detoxification of H2O2
What are the cytochromes for?
they do oxidative phosphorylation
What is guanylate cyclase for?
this is how NO is involved in stimulation of cGMP in smooth muscle
What does heme synthesis begin with and where?
Begins with glycine and succinyl coA in the mitochondria
What is the rate limiting enzyme in heme synthesis?
aminolevullnic acid synthase
What regulates aminolevullnic acid synthase?
Heme...when heme is high, the enzyme is inhibited
Which enzyme is effected in acute intermittent porphyria?
PBG Deaminase which is responsible for turning the mono purols into tetra purols
What increases the heme requirement in the cell during AIP?
a drug induces p450 which increases the heme requirement
What two things build up in AIP?
1) ALA because ala synthase is active with low heme
2) pyrrole
Which disease do you see lichenification and a defect in the ferrochelatase enzyme?
EPP--> erythropoietic protoporphryria
What are the toxic breakdown products in heme metabolism?
Biliverdin and then the reduction to bilirubin
What do biliverdin and bilirubin bind to so they are not toxic?
Serum albumin
What is the basis of the bilirubin toxicity?
Alters the mitochondrial membrane potential so cytochrome c can slip out and do the apoptotic pathway
What binds to bilirubin inside the liver to keep it from being toxic?
ligandin
What binds to bilirubin inside the liver to make it soluble for secretion in the bile?
glucaronic acid
What is the enzyme that makes diglucoronide bilirubin which is soluble to be excreted? What induces this enzyme?
1) UDP glucuronyltransferase
2) phenobarbital
What are the factors in neonatal jaundice?
1) increased hemolysis
2) decreased clearance of bilirubin
3) decreased bilirubin udp glucuronyl transferase
What things cause albumin to decrease its capacity to carry bilirubin and cause jaundice?
1) sulfanimides
2) certain antiinflammatory drugs
3) contrast dye
What is kernicterus and what enzyme is defective?
It is severe unconjugated hyperbilirubinemia with a defect in the UDP glucouronyltransferase, problems with getting high concentrations of bilirubin in the CNS
Which enzyme is mutated in Crigler-Najjar Syndrome Type I and Type II?
UDP glucuronal transferase gene
What is the therapy for Type II Crigler-Najjar Syndrome patients?
Phenobarbital
Why don't Type I Crigler-Najjar Syndrome patients respond to treatment?
They have mutations in the fundamental core exons of the enzyme