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Biochemistry

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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1. What is the function of biotin
Microarrays
Cofactor of carboxyltion enzymes: pyruvate carboxylase - acetate - CoA carboxylase - and propionyl - CoA carboxylase
B6
Ubiquitous - low Km - high affinity - low capacity low Vmax - uninduced by insulin

2. What does helicase do
The triphosphate bond
Phenylalanine hydroxylase
Oxidized hemoglobin precipiated within RBCs
Unwinds DNA template at replcation fork

3. How does ouabain work
Stop codon is recognized by release factor - and completed protein is released from ribosome
Inhibits the Na/K pump by binding the K side
Heme synthesis - urea cycle and gluconeogenesis - HUGs take two
B100

4. What enzyme converts phenylalanine to tyrosin
Phenylalanine hydroxylase
Inc intestinal absorption fo calcium and phosphate - inc bone resorption
Receptor tyrosine kinases - protein phosphatase - takes phosphate off glycogen phosphorylase kinase inactivating it
1/4 of offspring from 2 carrier parents are affected - often enzyme def - usually only seen in 1 generation - often more sever than AD - presents in childhood

5. If two alleles are present - but the active allele is deleted - what happens
Autosomal recessive diseases
Nissl body - enzyme and NTs
Disease
Unwinds DNA template at replcation fork

6. Type IV collagen
Basement membrane or basal lamina
Heterochromatin = HighlyCondensed
Phosphorylation - glycosylation - hydroxylation
Oxidized hemoglobin precipiated within RBCs

7. Acetyl - CoA carboxylase catalyzes what rxn
Muscle
Krabbes - galactocerebrosidase - galactocerebroside - AR
Acetyl - CoA to malonyl - CoA (2C to 3C)
LCAT (lecithin cholesterol acyltransferase)

8. Inhibition of thymidilate synthase and and DHFR lead to decrease In what substance
MRNA - tRNA
DTMP
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light
Delayed wound healing - hypogonadism - dec in adult hair - dysguesia - anosmia - may predispose to EtOH cirrhosis

9. What is codominance and give an example
Microtubules
Inc vit B6
Hepatic glycogenolysis >> hepatic gluconeogenesis > adipose release of FFA
Neither of 2 alleles is dominant - blood groups

10. What enzyme degrades a small amount of glycogen in lysosomes
Orotic acid to UMP
Acetyl - CoA
Alpha 1 -4 glucosidase
After citruline

11. What is the RDE of cholesterol synthesis
CG- 3 > AT-2 - More CG content - melting point goes up
Base + ribose
HMG- CoA reductase
NH2-(C=O) - NH2 one NH2 from ammonia the C=O from CO2 - and the other NH2 from aspartate

12. What causes Hartnup's disease
Mutations at different loci can produce the same phenotype - marfans - MEN 2B - homocystinuria; all cause marfinoid habitus - also albinism
Grows slowly - collapses quickly
AR disorder characterized by defective neutral amino acid transporte on renal and intestinal epith cells
NAD+

13. What is pleiotropy and given an example
1 gene had >1 effect on an individuals phenotype - PKU causes many seemingly unrelated symptoms ranging from mental retardation to hair/skin changes
Hereditary defect of renal tubular amino acid transporter for cystein - ornithine - lysine and arginine in PCT
Dopamine beta hydroxylase
Cofactor for LPL

14. What substances directly inhibit electron transport chain
Y shaped region along the DNA template where leading nad lagging strands are synthesized
Cytosol
One
Rotenone - CN- - antimycin A - CO

15. What does inc phenylalanine lead to...
Phenylketones in urine
P+q = 1
Conversion of NE to epi
In mitochondria - pyruvate to oxaloacetate - requires biotin - ATP - activated by acetyl coA

16. The pyruvate dehydrogenase complex serves In what reaction: products
Acetly- CoA - CO2 - NADH
Connective tissue
Alpha1 antitrypsin
Secretion of abnl thick mucus that plugs lungs - pancreas - liver

17. What is a nonsense mutation
Change resulting in early stop codon
HMG- CoA synthase
Metanephrine
CG- 3 > AT-2 - More CG content - melting point goes up

18. Type IV collagen is an important structural componenet of the BM for which 3 organs
ATP and methionine
Kidney - ears - eyes
Malonyl coa (+ biotin= palmitiate - 1 16C fatty acid)
Genetic code is conserved throughout evolution - except for mito - archaebacteria - mycoplasma - and some yeast

19. What does apoCII do
Medial dorsal nucleus of thalamus - mamillary bodies
II - VII - IX - X (1972) protein C and S
Cofactor for LPL
AMP - fructose 2 -6 BP

20. What are the findings in PKU
Mental retardation - growth retardation - seizures - fair skin - eczema - musty body odor
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
AMP - fructose 2 -6 BP
Inhibit DNA gyrase specific for prokaryotic topoisomerase

21. What is the initial transcript called and What is the capped and tailed transcript called
2 rings
Heterochromatin = HighlyCondensed
Initial is heterogenous nuclear RNA - the capped and tailed is called mRNA
B100

22. Gene imprinting implies that How many alleles are active at a single locus
Inc intestinal absorption fo calcium and phosphate - inc bone resorption
Alcohol version of glucose - can trap glucose in cell - aldose reductase
One
Loss of brush border enzyme causing bloating - cramps - osmotic diarrhea

23. What is the defectin IV - hypertriglyceridemia
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels
Poly A polymerase - signal is AAUAA
Fibrofatty replacement of muscle - cardiac myopathy
Hepatic overproduction of VLDL causing pancreatitis - elvelated TGs and VLDL

24. What is the hardy weinber heterozygote prevalence
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns
Cofactor of carboxyltion enzymes: pyruvate carboxylase - acetate - CoA carboxylase - and propionyl - CoA carboxylase
2pq
Type II

25. What does the CFTR channel do in the lungs - GI tract and skin
Euchromatin
Acetyl - CoA carboxylase (ACC)
Active secretion in lungs and GI - reabsorbs in skin
Thymic - parathyroid and cardiac

26. In what direction are DNA and RNA synthesized

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27. What is loss of heterozygosity and give an example
32 - malate aspartate shuttle
AR disorder characterized by defective neutral amino acid transporte on renal and intestinal epith cells
Tryptophan
If pt inherits or develops a mutation in a tumor suppresor gene - the complementary allele must be deleted/mutated before cancer develops - not true of oncogenes - retinoblastoma

28. Which part of the DNA binds RNA polymerase and multiple other TFs upstream from gene locus
CTG
Actin and myosin
Lack of proper dietary therapy during pregnancy leading to microcephaly - mental retardation growth retardation - congenital heart defects
Promotor - TATA box - and CAAT box - AT rich

29. An inability to convert orotic acid to UMP would be caused by a deficiency either of which two enzymes

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30. When does aspartate enter the urea cycle
Achondroplasia
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Dermatitis - glossitis - and diarrhea
After citruline

31. What are the findings in Lesch - Nyhan
Acetyl - CoA to malonyl - CoA (2C to 3C)
Changed AA (convservative - new AA is similar in chemical structure)
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Phosphorylation - glycosylation - hydroxylation

32. What does DNA ligase do
Antigen - antibody reactivity - can look for antigen or antibody in patients blood
Glucose 6 phosphate dehydrogenase (G6PD)
Reticulin - skin - blood vessels - uterus - fetal tissue - granulation tissue
Seals.

33. What does a defective Cl channel do
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light
1 ring
Nature and severity of phenotype vary from 1 individual to another - NF type 1
Secretion of abnl thick mucus that plugs lungs - pancreas - liver

34. Where does gluconeogenesis primarily happen and What are other sites where the enzymes are located
Liver - also in kidney and gut epithelium
Locus heterogeneity - ocular albinism is x- linked recessive
Binds to LDL receptor - mediates VLDL secretion
Gaucher's - beta glucocerebrosidase - glucocerebrosie - AR

35. What is the mutation in beckers muscular dystrophy - What is the severity and time of onset
Excess ATP - dATP - feeback inhibits ribonucleotide reductase - no DNA synthesis
Mutated dystrophin gene - less severe - adolescence
Colchicine
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)

36. What does vit C def cause
Biotin
Scurvy - swollen gums - bruising - hemarthrosis - anemia - poor wound healing - weakened immune response
Polycystic liver disease - berry aneurysm - mitral valve prolapse
Plasma membrane - 3Na out - 2K in - ATP on cytoplasmic side

37. ADPKD is associated with What additional conditions
Cri du chat
Polycystic liver disease - berry aneurysm - mitral valve prolapse
Carbomoyl phosphate synthetase II
PMNs

38. What is the physiologic role of dystrophin
ATP and alanine
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels
Anchor muscle fibers - primarily in skeletal and cardiac muscle
Tryptophan excretion in urine and dec absorption from the gut leading to pellagra

39. What are the purely ketogenic amino acids
Common metabolites like pyruvate and acetyl CoA and excess NH4+ converted to urea and exreted
HMG- CoA - brain to 2 molecules of acetyl - Coa - excreted in urine
Leu - lys
Flank pain - hematuria - HTN - progressive renal failure

40. What lab value can distinguish orotic aciduria from ornithine transcarbamoylase def?
Euchromatin
Keep glutathione reduced so it can detoxify free radicals and peroxides
Neural tube
OTC has hyperammonemia - orotic aciduira does not

41. What is the activated carrier for Co2
Plasma membrane - 3Na out - 2K in - ATP on cytoplasmic side
Biotin
Dec phenylalanine (contained in aspartame - Nutrasweet) inc tyrosine in diet
Phenylalanine hydroxylase - tetrahydrobiopterin cofactor

42. What shape does the RNA generate during splicing and why?
Malapsorption syndromes like sprue or CF or mineral oil intake
Lariat shape in order and remove intron precisely and join 2 exons
Krabbes - galactocerebrosidase - galactocerebroside - AR
Debranching enzyme

43. What happens do glycogen in skeletal muscle during exercise
Athralgias - fatigue - headaches - skin changes - sore throat - alopecia
Glycogenolysis to form glucose
75 to 90 - cloverleaf
Glutamate

44. What are the results of unbalanced translocation
Miscarriage - stillbirth - chromosomal imbalance (down - patau)
SAM
Riboflavin - cofactor in oxidation and reduction (FAD and FMN are derived from riboflavin)
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels

45. What are the functinos of vitamin A
Muscle
Antioxidant - constituent of visual pigment - essential for nl differntiation of epithelial cells into specialized tissue (pancreatic cells - mucus secreting cells) used to treat measles
ATP and methionine
IDL

46. What regulates whether FBPase -2 or PFK-2 is active
Protein kinase A
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns
Tuberous sclerosis
Progressive hreditary nephritis and deafness - associated with occular disturbances - due to abnl type IV collagen - usually x- linked recessive

47. What is the amino acid precursor for GABA and glutathione
Glycine - aspartate - glutamine
Citrate - isocitrate - alpha ketoglutarate - succinyl - CoA - succinate - fumarate - malate - oxaleoacetate
Wrinkles and acne
Glutamate

48. What substances inhibit phosphofructokinase -1
Malonyl coa (+ biotin= palmitiate - 1 16C fatty acid)
Phosphorylation excess glucose to sequester it - liver becomes blood glucose buffer
ATP - citrate
Glycine - aspartate - glutamine

49. facial lesions - hypopigmented 'ash leaf spots -' cortical and retinal hamartomas - seizures - mental retardation - renal cysts - renal angiomyolipomas - cardiac rhabdomyomas - inc risk of astrocytomas
Accelearted muscle breakdown
Tuberous sclerosis
B100
Proton gradient

50. What happens on the oxidative arm of the HMP shunt and What is the key enzyme
Reticulin - skin - blood vessels - uterus - fetal tissue - granulation tissue
Glucose 6P to CO2 - 2NADPH - ribulose 5P - G6PD - rate limiting step
Semiconservative - continuous and discontinuous strands (okazaki fragments)
CGG