Term
| What are the essential amino acids? |
|
Definition
-L-Leucine
-I-Isoleucine
-V-Valine
-T-Threonine
-M-Methionine
-F-Phenylalanine
-W-Tryptophan
-R-Arginine(children)
-K-Lysine
-H-Histidine |
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|
Term
| What are the strictly ketogenic amino acids? |
|
Definition
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Term
| What are the ketogenic amino acids, but can also be glucogenic? |
|
Definition
I-isoleucine
T-Threonine
F-Phenylalanine
Y-Tyrosine
W-Trytophan |
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Term
| What is released in the stomach that is important to protein digestion and absorption? |
|
Definition
HCl and pepsinogen
acidic conditions allow pepsinogen to undergo self-proteolysis, releasing PEPSIN |
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Term
| Where is pepsin found and what does it cleave? |
|
Definition
In stomach, cleaves proteins after R groups that are...
-hydrophobic(F,Y)
-acidic(D,E) |
|
|
Term
| What does the pancreas secrete in the small intestines? |
|
Definition
1) Bicarbonate
2) Trypsinogen
3) Chymotrypsinogen
4) Proelastase
5) Procarboxypeptidase |
|
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Term
| What is the role of Bicarbonate? |
|
Definition
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Term
| If there is inappropriate activation of one of the pancreatic enzymes, what results? |
|
Definition
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Term
| What catalyzes the conversion of trysinogen to trypsin? Where is this enzyme found? |
|
Definition
Enteropeptidase(also called enterokinase)
It is found on the brush border of the intestinal epithelium cells(enterocytes) |
|
|
Term
|
Definition
It activates the other pancreatic enzymes...
chymotrypsin
elastase
carboxypeptidase |
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|
Term
| Which amino acid dimer will be formed from digestion? |
|
Definition
| Cys-Cys(no enzyme to break or digest) |
|
|
Term
|
Definition
-Results from defect in transport of cystine, lysine, arginine, and ornithine
-Problem manifest in kidney(poor reabsorption from glomerular filtrate) and intestinal(poor absorption from diet) membranes
-Cystine accumulates in urine;relatively insoluble; stones develop
-NO amino acid deficiencies seen |
|
|
Term
| What is Hartnup's disease? |
|
Definition
-Defect in transport of NEUTRAL amino acids (I,L,F,T,W,V)
-affects both intestine and kidneys
-most pressing problem is lack of W(if Niacin low, trouble making NAD+)
-Pellagra like symptoms occur(diarrhea, dermatitis, dementis)
-TREAT with supplemental W and Niacin |
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|
Term
| What precursor can be synthesized to make glutamate, then it can be reprocessed to make Glutamine, Proline, and Arginine? |
|
Definition
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|
Term
| What precursor can be used to make aspartate, which can be modified to make asparagine? |
|
Definition
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|
Term
| What precursor can make serine then modified to make cysteine and glycine? |
|
Definition
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|
Term
| What precursor is used to make Tyrosine? |
|
Definition
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|
Term
| What precursor can be used to make Alanine? |
|
Definition
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|
Term
| B6 is the precursor for what important cofactor? |
|
Definition
|
|
Term
| What type of reactions is B6 or pyridoxal phosphate required? |
|
Definition
1) Transaminations
2) Racemizations (D to L configuration)
3) ß-elimination reactions
4) ß-addition reactions
5) gamma-eliminations |
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|
Term
| What are the 3 reactions that can fix free ammonia? |
|
Definition
1) glutamine synthetase
2) glutamate dehydrogenase
3) CPS-I |
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Term
| Glutamine is made from NH3, ATP, and Glutamic acid using? |
|
Definition
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Term
| Asparagine is made from Asp, ATP, and Gln as a nitrogen donor using what? |
|
Definition
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Term
| What enzyme makes Gly from Ser? Is there any necessary cofactors? |
|
Definition
Serine Hydroxymethyl Transferase
requires- THF |
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Term
| What degradative reactions require THF? |
|
Definition
1) Serine (uses N5, N10 methylene THF)
2) Formate (N10 formyl THF)
3) Histidine degrastion (N5 formimino THF)
4) Glycine cleavage enzyme(N5,N10 methylene THF) |
|
|
Term
| What Biosynthetic reactions require THF? |
|
Definition
1) dUMP to TMP (N5,N10 methylene)
2) Glycine to serine (N5,N10 methylene)
3) Homocysteine to methionine (N5 methyl THF)
4) Purine biosynthesis (N10 formyl) |
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|
Term
| What are the methyl donors in biochemistry? |
|
Definition
1) N5-Methyltetrahydrofolate-only used in conversion of homocysteine to methionine
2) SAM (S-Adenosylmethionine)-used for all other methyl transfer reactions- Product is S-adenosylhomocysteine,
which then makes homocysteine |
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|
Term
| What enzyme will make Tyr from Phe? What cofaactors are needed if any? |
|
Definition
Phenylalanine Hydroxylase
requires THB(tetrahydrobiopterin) |
|
|
Term
| After Tyr synthesis, what is needed to regenerate THB? |
|
Definition
| NADPH, THB needs to be reduced |
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|
Term
| Cysteine is derived from? |
|
Definition
|
|
Term
| What enzyme is necessary for Cysteine biosynthesis? |
|
Definition
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|
Term
| What two reactions is B12 required for? |
|
Definition
1) L-methylmalonyl CoA to succinyl CoA
2) Homocysteine to methionine(regenerates THF) |
|
|
Term
| If B12 is not activated, what disease will result? |
|
Definition
| Megoblastic anemia; neurological symptoms |
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|
Term
| Amino Acid Biosynthesis is mostly regulated by? |
|
Definition
| feedback inhibition of branch pathways |
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|
Term
| All amino acids are degraded to one of seven family members, what are these? |
|
Definition
1) Acetoacetyl-CoA
2) Acetyl-CoA
3) Pyruvate
4) alpha-ketoglutarate
5) Succinyl-CoA
6) Fumarate
7) Oxaloacetate |
|
|
Term
| What four disorders result from defects in Phe degradation? |
|
Definition
1) PKU
2) Alcaptonuria
3) Tyrosinemia, type 1
4) Tyrosinemia, type 2 |
|
|
Term
|
Definition
Buildup- of homegentisic acid in urine
Signs- black urine, may lead to arthritis |
|
|
Term
|
Definition
Two types
-Classical-missing Phenylalanine hydroxylase
-missing ability to make or regenerate THB
Buildup- Phenylpyruvate (TA of phe) and Phe
Symptoms-neuronal damage, mental retardation
Treat-restricted Phe diet |
|
|
Term
| If you put a pt w/ PKU on a proper diet and they still have symptoms then? |
|
Definition
They probably have a problem with THB.
So keep restricted PHE diet
-supplement with DOPA, 5-hydroxytryptophan, THB |
|
|
Term
|
Definition
lacks- fumarylacetoacetate hydrolase
symptoms- vomiting, failure to thrive, cabbage-like odor, liver failure, early death in accute form |
|
|
Term
|
Definition
Defect in tyrosine aminotransferase (tat)
Symptoms- skin and eye lesions, neurological problems
Treat- low phe and tyr diet |
|
|
Term
|
Definition
Lacks-
1) methionine synthase
2) N5,N10-methyl tetrahydrofolate reductase
3) Cystathionine-ß-synthase
Causes- elevated levels of homocysteine and methionine in the blood and urine
Symptoms- dislocation of optic lens, osteoporosis, mental retardation(poss elevated risk for heart disease)
Treatment-(only effective if enzyme has reduced affinity for these)
1) B6 effective in lowering homeocysteine 50% of cases
2) B12
3) Folic Acid |
|
|
Term
| What does homocysteine do? |
|
Definition
-It inhibits endothelial cell growth and promotes smooth cell proliferation. (This exacerbates the problems of atherosclerosis.
-Blocks the action of an inhibitor of the coagulation cascade; thus coagulation is poorly controlled, clots can form, and thrombosis results. (deep vein thrombosis is common in these pts) |
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|
Term
| Taking what pre-conceptually reduces the risk of neural tube defects? |
|
Definition
|
|
Term
| What does extra folic acid do? |
|
Definition
| A common mutation in humans is a temperature-sensitive N5, N10 methylene tetrahydrofolate reductase (the enzyme which makes N5-methyl THF). With too little N5-methyl THF, homocysteine accumulates. Overcome by taking folic acid;increases substrate levels such that sufficient N5-methyl THF can be made |
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|
Term
| What produces B12 and how can we obtain it? |
|
Definition
| produced by bacteria, obtained in milk, meat |
|
|
Term
| What leads to pernicious anemia? |
|
Definition
| Lack of intrinsic factor that is secreted by the stomach. This factor binds to B12, so it is able to be transported into the intestinal epithelial cells. |
|
|
Term
| What does B12 have that is similar to a porphyrin ring? |
|
Definition
| corrin ring complexed with cobalt atom |
|
|
Term
| What two enzymes are important in B12 processing, if this doesn't occur vitamin deficiency will occur? |
|
Definition
1) Methyl-cobalamin-used to transfer methyl group from N5-methyl THF to homocysteine
2) Adenyl-cobalamin-used in the conversion of methyl-malonyl-CoA to succinyl-Coa |
|
|
Term
| Both B12 and Folic Acid deficiencies lead to? |
|
Definition
|
|
Term
| B12 deficiency also leads to? |
|
Definition
| neurological problems-tingling in extremities, mental status changes; folate deficiency does not cause this |
|
|
Term
| Why do neurological problems happen with B12 deficiency? |
|
Definition
| Lack of SAM-leads to hypomethylation in the brain(altering of gene expression, myelin sheath formation) |
|
|
Term
| What pathway is in the liver so hypomethylation does not occur there? |
|
Definition
| betaine pathway(trimethylglycine) |
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|
Term
| Lack of what enzyme cause Maple Syrup Urine Disease? |
|
Definition
| The alpha-ketoacid dehydrogenase is defective. this enzyme catalyzes the decarboxylation of all three amino acids, leucine, isoleucine, and valine |
|
|
Term
| What three amino acids are affected in maple syrup urine disease? |
|
Definition
| leucine, isoleucine, valine |
|
|
Term
| Where is the primary site of branched chain AA metabolism? |
|
Definition
| muscle; liver has low levels (of the alpha-ketoacid DH) which catalyzes oxidative carboxylation |
|
|
Term
What are the symptoms of Maple Syrup Urine Disease?
Poss. treatments? |
|
Definition
ketoacidosis and mental retardation
Some respond to thiamin(B1)-required for oxidative carboxylation
dietary restriction of branched chain AA, not effective since they are essential |
|
|
Term
| Heme is what type of ring? What is heme synthesized from? |
|
Definition
-porphyrin ring
-synthesized from succinyl-CoA and glycine |
|
|
Term
| The corrnin ring is found in what? What is it synthesized from? |
|
Definition
| B12, synthesized from succinyl-CoA and glycine in non-mammalian systems, hence why we need to obtain in our diet from meats, or fortified cereals |
|
|
Term
| What is the rate limiting step in heme synthesis? |
|
Definition
| ∂-aminolevulinic acid synthase |
|
|
Term
What does ∂-aminolevulinic acid synthase do?
Where does this rxn happen? |
|
Definition
Take succinyl-CoA and glycine and makes ∂-aminolevulinic acid.
Occurs in the mitochondria, product leaves and then pathwat ontinnues in the cytosol |
|
|
Term
| What is the inhibitor of ∂-aminolevulinic acid synthase? |
|
Definition
|
|
Term
| What happens in lead poisoning? |
|
Definition
1) lead inhibits ∂-aminolevulinic acid dehydratase
2) ∂-aminolevulinic acid accumulates and is secreted in the urine
3) heme levels are very low
4) anemia results |
|
|
Term
| What does ∂-aminolevulinc acid dehydratase do? |
|
Definition
| It is a condensation rxn, that takes 2 ∂-aminolevulinc acids and makes porphobilinogen |
|
|
Term
| Four porphobilinogen condense to form? |
|
Definition
|
|
Term
| The linear tetrapyrrole cyclizes to make? |
|
Definition
| uroporphyriogen III, goes on to make heme or vit B12 |
|
|
Term
| In general terms, defects in heme biosynthesis are known as? |
|
Definition
|
|
Term
| If a precursor has a double bond(in this case for porphyrias), exposure to what is no good? |
|
Definition
| UV light- creates radical intermediates which react with O2 to create superoxide, which damages and destroys skin cells (this is because our skin cells are exposed to the most UV light) |
|
|
Term
| Since our test is on Halloween, where does Liebermann think the vampire legend came from? |
|
Definition
| Pts with porphyrias(heme sensitive), person is photopobic andand needs to replenish heme by eating very rare(bloody) meats. |
|
|
Term
| Where does heme degradation normally occur? |
|
Definition
|
|
Term
| Heme is broken down into? |
|
Definition
|
|
Term
|
Definition
buildup of bilirubin
-results from enhanced red cell destruction
-liver damage
-immature conjugation system |
|
|
Term
| What happens to bilirubin in the liver? |
|
Definition
conjugated to glucuronic acid-enhances its solubility
(newborns sometimes have an immature conjugation system, leading to neonatal jaundice) |
|
|
Term
| What is necessary in heme degradation? |
|
Definition
|
|
Term
| What are they aspects of regulation of amino acid degradation(4)? |
|
Definition
1) substrate availability
-a-Km for aa-tRNA synthetase is lower than Km for aa degradation
-b-high levels of aa will at least start degradative pathway
2) there is feedback inhibition(never learned anything specific)
3) enzymes levels regulated(partly from our diet)
4) Nitrogen flow is regulated by Glutamate dehydrogenase and glutamine synthetase |
|
|
Term
| What is the role of alanine amino acid degradation? |
|
Definition
1) proteins are degraded for energy
2) free NH3s result
3) glutamate DH fixes NH3 into glutamate
4) alpha-ketoglutarate and pyruvate undergo a transamination rxn in the muscle creating glutamate and alanine.
5) Alanine flows through our blood til it reaches our liver
6) Alanine undergoes reverse of the transamination rxn producing pyruvate and Glutamate
7) Glutamate is reacted on by Glutamate DH and free NH3 is fixed into uric acid from the urea acid cycle |
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|
Term
| What are the various roles of Glutamine(depends on tissue needs)? |
|
Definition
1) fuel for intestine, kidney, and immune system
2) removes ammonia from the nervous system
3) kidney uses ammonium ion to buffer urine |
|
|
Term
| What are the major gluconeogenic substrates? |
|
Definition
|
|
Term
| What type of amino acids are predominantly used as fuels? |
|
Definition
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