Term
| What is the acronym used to describe the essential AAs? |
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Definition
P –phenylalanine PHE
V –valine VAL
T –tryptophan TRP
T –threonine THR
I –isoleucine ILE
M –methionine MET
H –histidine HIS
A-Arginine ARG (only when healing wounds, growing, or pregnant)
L –leucine LEU
L –lysine LYS
(all bcaa's are essential) |
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Term
| What are the two sources for proteins? |
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Definition
| Endogenous proteins, proteins from diet |
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Term
Name the 11 AAs that can be made and their precursors
Which one can't be made from glucose? |
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Definition
Alanine (from Pyruvate in a TA rxn)
Arginine (from glutamate)
Asparagine (from aspartate)
Aspartate (from OAA)
Cysteine (from methionine)
Glutamate (from a-Ketoglutarate in a TA rxn)
Glutamine (from glutamate)
Glycine (from serine)
Proline (from glutamate)
Serine (from 3-phosphoglycerate)
Tyrosine (from Phenylalanine; not glucose) |
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Term
| What three steps occur from 3-phosphoglycerate to serine? |
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Definition
1 oxidation of secondary alcohol to ketone (3-phosphoglycerate dehydrogenase)
2 transaminase
3 phosphoserine phosphotase
CO2-
-
CHOH
-
CH2O-P
to
CO2-
-
HCNH3+
-
CH2OH |
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Term
| Give the reaction catalyzed by serine hydroxymethyltransferase |
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Definition
| FH4 + Serine --serine hydroxymethyltransferase (PLP)--> N5, N10-Methylene FH4 + Glycine |
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Term
| What is a good test for b-12 deficiency? and Why? |
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Definition
The test for methylmalonyl CoA
Methylmalonyl coA mutase needs cyanocobalamin
Propionyl coA –propionyl coA carboxylase→ Methylmalonyl coA
Methylmalonyl coA --Methylmalonyl coA mutase→ Succinyl coA |
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Term
| What are the sources of propionyl CoA in the body? (6) |
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Definition
Four AA’s whose carbons can give rise to propionyl CoA: Valine, isoleucine, threonine, methionine (VITM)
When cholesterol becomes bile salts, propionyl coA is made by the cleaving of C 25, 26, 27
Short chain FA’s from fiber become propionyl coA in colonocytes |
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Term
| Describe methionine to succinyl CoA (5) |
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Definition
| Carbons from methionine become homocysteine by the methylation cycle, but then become to a-ketobutyrate --cystathionine synthase→ propionyl coA --BCKAD→ d-methylmalonyl coA → L-methylmalonyl CoA → Succinyl CoA (anapleurotic pathway) |
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Term
| Describe your body’s synthesis of alanine from glucose |
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Definition
| Glucose →→→ pyruvate ←ALT→ Alanine |
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Term
| Describe your body’s synthesis of aspartate and asparagine from glucose (5) |
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Definition
| glucose → pyruvate → (tca) → OAA <--transamination→ aspartate --asparagine synthetase→ Asparagine |
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Term
| Describe the body's production of glutamate and glutamine from glucose (6) |
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Definition
glucose → pyruvate → (tca) → a-KG <–transaminase→ Glutamate
or a-KG + NH4+ + NADPH ←GDH→ Glutamate + NADP+
Glutamate + ATP --glutamine synthetase→ Glutamine + ADP + Pi |
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Term
| What three AAs can glutamate make? |
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Definition
| Glutamine, Arginine (via ornithine), & Proline |
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Term
| Describe pheynylalanine to tyrosine |
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Definition
Phenylalanine + O2 + tetrahydrobiopterin (BH4) --Phenylalanine hydroxylase→ Tyrosine + H2O + dihydrobiopterin (BH2)
dihydropteridine reductase then reconverts BH2 to BH4 using NADH
(BH4 made from GTP) |
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Term
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Definition
| 2 mutated genes that code for phenylalanine hydroxylase; results in high levels of phenylalanine if it is consumed |
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Term
| What is non-classical PKU? |
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Definition
2 mutated genes that code for Dihydrobiopterine reductase
can in some ways be even more sever than classical PKU since Dihydrobiopterine reductase hydroxylates all aromatic AAs: trp, phe, tyr |
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Term
| List the six entry points into mainstream metabolism when the carbon skeletons of amino acids are catabolized |
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Definition
(1) α-ketoglutarate
(2) succinyl CoA
(3) fumarate
(4) oxaloacetate
(5) pyruvate
(6) acetyl CoA
Pyruvate/4 TCA cycle intermediates: If the amino acid gives rise to pyruvate or to one of those 4 places in the TCA cycle, those would be amino acids that your liver could use to make glucose, i.e. gluconeogenic. Once in the TCA cycle they could get to malate and then to glucose.
Acetyl CoA: Once these amino acids give rise to acetyl CoA, the carbons CANNOT be used to make glucose, there’s no way to do that. Just like a fatty acid with an even number of carbons cannot be used to make glucose because β-oxidation of that even-numbered fatty acid would give rise to acetyl CoA. But if acetyl CoA can enter the TCA cycle why aren’t we saying that it’s adding to the number of carbons for glucose? Those carbons are lost as CO2. But amino acids that go to acetyl CoA can give rise to ketone bodies, so they might be called ketogenic amino acids. |
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Term
What are the three a-keto dehydrogenase complexes we've learned thus far?
What 4 enzymes require TPP as a cofactor |
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Definition
1) α-ketoglutarate dehydrogenase (α-KG DH)
2) pyruvate dehydrogenase (PDC/PDH)
3) branched chain keto-acid dehydrogenase (BCKADH)
--
The 4 enzymes require TPP as a cofactor are all of the above enzymes, plus transketolase (learned in biochem 3) |
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Term
| What are the 5 cofactors for a-keto dehydrogenase complexes? |
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Definition
1) thiamine pyrophosphate (TPP, vitamin B1) – recycled (participates in decarboxylation)
2) FAD – recycled
3) NAD+ – consumed
4) Coenzyme A (pantothenic acid) – consumed
5) lipoic acid – recycled
Think of it as b-vitamins 1, 2, 3, 5, & alpha-lipoic acid |
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Term
| Name the amino acid precursor(s) that your body uses to make carnitine (2) |
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Definition
synthesis requires lysine and vitamin c as a cofactor
three methyl groups that come from three methionines in the form of SAM |
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Term
| Name the amino acid precursor(s) that your body uses to make glutathione (3) |
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Definition
| glutamate-cysteine-glycine |
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Term
| Name the amino acid precursor(s) that your body uses to make conjugation of bile salts-- also name the amino acid precursor for synthesis of taurine (3) |
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Definition
glycine and taurine (made from cysteine) used
taurine has a side chain that looks like sulfuric acid, indicating cysteine as the AA precursor |
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Term
| Name the amino acid precursor(s) that your body uses to make NAD+ |
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Definition
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Term
| Name the amino acid precursor(s) that your body uses to make purine nucleotides (3) |
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Definition
| Requires glycine, aspartate, and 2 glutamines for production |
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Term
| Name the amino acid precursor(s) that your body uses to make pyrimidine nucleotides (2) |
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Definition
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Term
Name the amino acid precursor(s) that your body uses to make thyroid hormones
also what are the names of the two thryoid hormones and what distinguishes them chemically? |
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Definition
two tyrosines
T3 and T4 numbers indicate number of iodine atoms
3,5,3’,5’-Tetra-iodothyronine (T4) aka [ “Thyroxine” ] – need to know
3,5,3’-Tri-iodothyronine (T3) |
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Term
| Name the amino acid precursor(s) that your body uses to make heme-- also say which TCA cycle intermediate is required (3) |
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Definition
Precursors: Iron, 8 glycines, and 8 succinyl coA’s,
2 glycines and 2 succinyl coA’s per ring |
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Term
| Name the amino acid precursor(s) that your body uses to make creatine--also know the rxn catalyzed by creatine kinase |
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Definition
Methionine as SAM
Glycine + Arginine → Ornithine + Guanidino-acetate
Guanidino-acetate + SAM --Methylation→ S-adenosyl homocysteine + Creatine
ADP + Creatine-Phosphate --creatine kinse--> ATP + Creatine |
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Term
| Name the amino acid precursor(s) that your body uses to make catecholamines and the three catecholamines that can be made (6) |
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Definition
AA precursor is (phenylalanine →) tyrosine → dopa → dopamine → norepinephrine –SAM methylation→ epinephrine
Catechol – benzene ring with 2 para hydroxyl groups |
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Term
| Name the amino acid precursor(s) that your body uses to make melanins (4) |
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Definition
| (phenylalanine →) tyrosine –tyrosine hydroxylase (Cu dependant)→ dopa → melanins |
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Term
| Name the amino acid precursor(s) that your body uses to make serotonin (2) |
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Definition
| Tryptophan → 5-Hydroxytryptophan → Serotonin |
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Term
| Name the amino acid precursor(s) that your body uses to make melatonin (4) |
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Definition
| Tryptophan → 5-Hydroxytryptophan → Serotonin → N-acetylserotonin –SAM methylation→ Melatonin |
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Term
| Name the amino acid precursor(s) that your body uses to make histamine (duh) |
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Definition
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Term
| Name the amino acid precursor(s) that your body uses to make gamma amino butyric acid (GABA) and describe its role in our bodies |
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Definition
Glutamate
Can cause hyperpolarization via allowing Cl- to come into the cell |
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Term
Describe the rxn catalyzed by glutathione peroxidase
what makes it unique as an enzyme? |
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Definition
2 GSH H2O2 --glutathione peroxidase→ GSSG + H2O (done in order to detox and end the potential threat of H2O2 as a free radical, and other peroxides as well)
glutathione peroxidase has an AA which selenium (Se) in it--selenocysteine, has selenium instead of sulfur (probably extra credit question) known as the “21st” AA |
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Term
Describe the rxn catalyzed by GSH reductase
Also, what makes GSH unique as a peptide? |
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Definition
GSSG NADPH --glutathione reductase→ 2 GSH NADP+
Ribosomes use a-carboxyl group to make peptides; GSH not made by a ribosome so the a-carboxyl group is not used |
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Term
| Draw a purine & number its carbons/nitrogens |
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Definition
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Term
| Draw a pyrimidine & number its carbons/nitrogens |
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Definition
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Term
| Name the amino acid precursor(s) that your body uses to make nitric oxide and describe its roles in our bodies (5) |
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Definition
Precursor: Arginine
Neurotransmitter in brain
Vasodilator
Prevents clotting
Important to how certain immune cells kill bacteria |
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Term
| Describe your body’s conversion of dietary folate (folic acid, F) into dihydrofolate (FH2), and of FH2 into tetrahydrofolate (FH4) |
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Definition
| NADPH is reducing agent in both Folate –dihydrofolate reductase→ Dihydrofolate and again –dihydrofolate reductase→ Tetrahydrofolate |
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Term
| What is dUMP and why is it important? |
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Definition
deoxyuridine monophosphate
Uracil
|
deoxyribose - P
can be turned into thymine nucleotides
dUMP –Thymidylate synthase→ dTMP (aka thymidylate)
dTMP – deoxythymadine monophosphate
Thymine
|
deoxyribose - P |
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Term
| What groups can FH4 carry? (4) |
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Definition
| formyl (aldehyde), methenyl, methylene, methyl |
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Term
Explain how a dietary folate deficiency causes megaloblastic
Explain how b-12 deficiency can also cause this problem and be masked via folate supplementation |
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Definition
Without folate, DNA replication becomes impossible; which leads to slowed cell division
In b-12 deficiency, methyl FH4 can no longer be used to make nucleotides, the cells cannot therefore divide, and the RBCs become larger than usual
If anemia disappears due to folate supplementation, problem may still be a b-12 deficiency; symptoms may be masked long enough for nerve damage to occur due to b-12 deficiency |
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Term
| Name the amino acid that donates the one-carbon group to FH4 |
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Definition
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Term
| Describe N5, N10-Methylene FH4 to N10-formyl FH4 |
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Definition
N5, N10-Methylene FH4 NAD(P)+ <--> N5, N10-Methyenyl FH4 + NAD(P)H
N10-Methyenyl FH4 <--> N10-formyl FH4 |
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Term
| What is at the core of b-12, and what are the two forms for b-12 used as cofactors? Where is it found in nature? |
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Definition
A corrin (porphorin ring system wrapped around a cobalt)
two forms for b-12 used as cofactors: deoxyadenosyl and methylcobalamin
Only bacteria make b-12 |
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Term
| What cells secrete intrinsic factor? |
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Definition
| cells in the salivary glands that produce intrinsic factor (binds to b-12 and lets it go); also secreted by parietal cells |
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Term
| What is the role of R-binders? |
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Definition
| To bind to free b-12 in the mouth and stomach until intrinsic factor takes over later and is absorbed in the ileum |
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Term
| Why are zymogens important for b-12 absorption? |
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Definition
| To digest the initial proteins holding on to B12 so intrinsic factor can attach |
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Term
| Describe the two reactions in your body that are known to require a cofactor derived from vitamin B12 |
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Definition
homocysteine –methionine synthase→ methionine
methionine synthase has a b-12 which resides in its active site, where N5-methyl FH4 donates a methyl group to the b-12 in methionine synthase and becomes FH4, the methyl then gets donated to homocysteine making it methionine
methylmalonyl coA –Methylmalonyl coA mutase (deoxyadenosyl cobalamin)→ succinyl coA |
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Term
| Describe the 5 common uses of SAM for methylation that we must know |
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Definition
Norepinephrine --SAM → Epinephrine
Guanidinoacetate --SAM → creatine
Nucleotides --SAM → Methylated nucleotides
Phosphatidylethanolamine --SAM → Phosphatidylcholine
Acetylserotonin --SAM→ Melatonin
(even more rxns not mentioned) |
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Term
|
Definition
| Methionine adenosyltransferase |
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Term
| Draw a SAM schematic and show which methyl group becomes transferred |
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Definition
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Term
| Describe the methylation cycle (6) |
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Definition
Methionine + ATP –MAT→ SAM + PPi + Pi
Which will form into 3 Pi as PPi breaks down
SAM + Precursor --methyl transferase→ SAH + CH3-product
methyl transferase (aka transmethylase) is a family of enzymes
SAH --SAH hydrolase→ Homocysteine + Adenosine
homocysteine + FH4 –methionine synthase (b-12)→ methionine + N5-Mehtyl FH4 |
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Term
| Describe the rxn catalyzed by methylene tetrahydrofolate reductase |
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Definition
| methylene tetrahydrofolate + NADH --methylene tetrahydrofolate reductase→ methyl tetrahydrofolate + NAD+ |
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Term
| Describe cysteine from methionine and serine (3) |
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Definition
SAH --SAH hydrolase--> homocysteine + adenosine
serine + homocysteine <--Cystathionine B-synthase (PLP)--> cystathionine + H2O
cystathiononine --cystathionase (PLP)→ a-Ketobutyrate + NH3 + cysteine |
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Term
| What are some of the problems excess homocysteine is associated with? (4) |
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Definition
| Dimentia, dislocated eye lenses, cardiovascular problems, skeletal problems |
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Term
Name the sources of betaine learned in class (6)
Why is it important for lowering one's levels of homocysteine? |
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Definition
sugar beats, wheat, quinoa, spinach, shellfish, can be made from choline
homocysteine + betaine –betaine homocysteine methyl transferase→ Methionine + dimethyl glycine |
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Term
|
Definition
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Term
| Describe the rxns that convert choline to betaine (2) |
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Definition
Choline is oxidized twice
Choline NAD+ –choline dehydrogenase→ NADH betaine aldehyde
Choline aldehyde + NAD+ --choline aldehyde dehydrogenase→ NADH + Betaine |
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Term
| Recognize the chemical structure of tetrahydrofolate |
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Definition
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Term
| Draw out the three steps that occur from 3-phosphoglycerate to serine & then glycine |
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Definition
3-phosphoglycerate NAD+ --phosphoglycerate dehydrogenase-->3-phosphohydroxypyruvate + NADH + H+
3-phosphohydroxypyruvate + GLU --phosphoserine aminotransferase--> 3-phosphoserine + a-KG
3-phosphoserine + H2O --phosphoserine phosphatase--> Serine
Serine + FH4 --serine hydroxymethyltransferase (PLP)--> N5, N10-methylene FH4 + Glycine |
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