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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. Which step in the de novo purine and pyrimidine synthesis pathway requires just aspartate
Pyruvate to oxaloacetate (3C to 4C)
Trisomy 13 - severe mental retardation - rocker bottom feet - micophthlamia - microcephaly - cleft lip/palate - holoprosencephaly - polydactyly - congenital heart disease - death usually within the first year
Sever atherosclerotic disease early in life - and tendon xanthomas on the achilles - MI may develop before 20
Orotic acid to UMP

2. Which bond is stronger AT or CG and why? What is the laboratory consequence of this?
Gaucher's - beta glucocerebrosidase - glucocerebrosie - AR
CG- 3 > AT-2 - More CG content - melting point goes up
Fructose 1 -6 bisphosphate
Malapsorption syndromes like sprue or CF or mineral oil intake

3. How is Lesch Neyhan inherited
Leu - lys
X- linked recessive
Glycolysis and aerobic respiration
Transmitted through both parents - affected mother may have affected children - affected father will have affected children

4. In which single strand DNA repair mechanism do specific endonucleases release the oligonucTIDE containing bases and DNA poly and ligase fill and reseal - and what disease occures when this is mutated
Fed
CFTR gene - 7 - Phe 508
Offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light

5. Type I collagen
Histidine
Coenzyme A - lipoamide
Miscarriage - stillbirth - chromosomal imbalance (down - patau)
Bone - skin - tendon - dentin - fascia - cornea - late wound repair

6. What are the two possible causes of albinism
Flagella - cilia - mitotic spindles
Lack of tyrosinase (no melanin) AR ordefective tyrosine transporters (less tyrosine) - can results in lack of migration of NC cells
Phosphorylation excess glucose to sequester it - liver becomes blood glucose buffer
Metanephrine

7. What does apoE do
Wernicke - korsakoff - dry and wet beriberi
Transmitted only through mother - all offspring of affected females may show signs of disease
Mediates extra remnant take up
Inhibits RNA polymerase II - found in death cap mushrooms

8. What is incomplete penetrence and give an example
Not all individuals with a mutant genotype show the mutant phenotype
Galactitol - galactose appears in blood and urine - can cause infantile cataracta - AR
Glycolysis - fatty acid synthesis - HMP shunt - protein synthesis (RER) - steroid synthesis (SER)
Foliage - small reserve in liver - eat green leaves

9. Delivers dietary TGs to peripheral tissues - delivers cholesterol to liver in the form of remnants - mostly depleted of TGs - secreted by intestinal epith cells
Metachromatic leukodystrophy - arylsulfatase A - cerebroside sulfate AR
DTMP
Chylomicrons
Citrate - acetyl coa from mito to cyto

10. How do you diagnose CFTR
Hydroxyurea - inhibits ribonucleotide reductase - 6 MP - blocks de novo purine synthesis - 5 FU inhibits thymidilate synthase - MTX - inhibits DHFR - Trimethroprin inhibits bacterial DHFR
Presence of both nl and mutated mtDNA resulting in mitochondrial inherited disease
Inc Cl - in sweat
Proline and lysine - vit C

11. colon becomes covered witih adenomatous polyps after puberty - progresses to colon cancer unless resected
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)
Backup of substrate (pyruvate and alanine) resulting in lactic acidosis - congenital or acquired from thiamine def in EtOH - neuro defects
FAP
ADEK - dependent on gut (ileum) and pancreas - accumulate in fat and can cause toxicity

12. What causes patau's syndrome and What is it
Mcardle's - skeletal muscle glycogen posphorylase
Degredation of TG circulating in chylomicrons and VLDLs
Trisomy 13 - severe mental retardation - rocker bottom feet - micophthlamia - microcephaly - cleft lip/palate - holoprosencephaly - polydactyly - congenital heart disease - death usually within the first year
Directly inhibit the Na/K pump which leads to indirect inhibition of Na/Ca exchange - inc calcium inside the cell - inc cardiac contractility

13. What does aminoacyl tRNA synthetase do the AA before and after it binds to tRNA - and what happens if it's the wrong the match
Alpha1 antitrypsin
Scrutinizes - hydrolyzes the bond
Inhibits EtOH dehydrogenase and is an antidote for methanol and ethylene glycol poisoning
Zero

14. What are the function of vit C
Cytosol - F 1 -6 BP to fructose 6 Phosphate
Early in life - AR - inability to synthesize lipoproteins due to def in apoB100 and B48 - intestinal biopsy shows accumulation within enterocytes due to inability to export absorbed lipid as chylomicrons - failure to thrive - steatorrhea - acanthocyt
Antioxidant - facilitates iron absorption by keeping iron in the Fe2+ reduced state - necessary for hydroxylation of proline and lysine collagen bridges - necessary for dopamine beta hydroxylase which converts DA to NE
Phenytoin - MTX - and sulfonamides

15. Patients with chronic granulomatous disease are at increased risk of infection From which kind of organisms
Locus heterogeneity - ocular albinism is x- linked recessive
Catalase positive (catalase neg produce H2O2 the cell can use) like S. aureus or aspergillus
Phosphorylation - glycosylation - hydroxylation
HMP shunt

16. What is the rate limiting enzyme in cholesterol synthesis
Phenylketones in urine
HGPRT - defective purine salvage - excess uric acid production
Cofactor for LPL
HMG- CoA (HMG- CoA to mevalonate

17. What does GFAP stain for
Acetoacetate and beta hydroxybutyrate
Neuralgia
Chylomicrons
Regulatory proteins that control cell cycle events; phase specific; activate CDKs

18. What does PURe As Gold and CUT The Py stand for
Purines= A - G pyrimidine = C - T (U)
Oxalacetate
ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets
Excess ATP - dATP - feeback inhibits ribonucleotide reductase - no DNA synthesis

19. What is the structure of elastin
ATP - citrate
Tropoelastin with fibrillin scafolding
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver
Conversion of NE to epi

20. What step of uric acid synthesis does xanthine oxidase catalyze
Inc intake of ketogenic nutrients - high in fact content or inc lysine or leucine
Converted to THF - a coenzyme for one - carbon transfer/methylation reactions - important for synthesis of nitrogenous bases in DNA and RNA
Hypoxanthine to xanthing and xanthine to uric acid
Hepatic glycogenolysis - adipose tissue release of FFA - muslce and liver FFA - hepatic gluconeogenesis from peripheral tissue lactate and alanine and from adipose tissue glycerol and proprionyl - coA (odd chain FFA)

21. What is the function of Zinc
ATP
LCAT (lecithin cholesterol acyltransferase)
Essential for the activity of over 100+ enzymes - important in the formatio of zinc fingers -
Mutated dystrophin gene - less severe - adolescence

22. What does vit C def cause
Scurvy - swollen gums - bruising - hemarthrosis - anemia - poor wound healing - weakened immune response
HMG- CoA synthase
LDL
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

23. What substances directly inhibit electron transport chain
Alpha and beta tubulin - dimers have two GTP bound
Actin and myosin
Rotenone - CN- - antimycin A - CO
Passed to glutamate - then to alanine enters blood - enters liver - coverted to pyruvate and transfers ammonium back to glutamate which gives it to the urea cycle

24. How does cytosine become uracil
X- linked recessive
Change resulting in early stop codon
Asp and Glu
Deamination

25. What apolipoproteins are on chylomicrons
Unmethylated - newly synthesized - HNPCC
Acetoacetate and beta hydroxybutyrate
DNA
B48 - AIV - CII - E

26. What are Heinz bodies
Oxidized hemoglobin precipiated within RBCs
Poor defense from oxidizing agents - fava beans - sulfonamides - primaquine - antituberclosis drugs leadig to hemolytic anemia.
Mental retardation - macro - orchidism - long face with large jaw - large everted ears - autism - and mitral valve prolapse
IDL

27. Where is vit A found in the diet
B100 and E
Microarrays
Orotate precursor - with PRPP added later
Liver and leafy veggies

28. What is pleiotropy and given an example
9+2 arrangement of microtubules
PMNs
Miscarriage - stillbirth - chromosomal imbalance (down - patau)
1 gene had >1 effect on an individuals phenotype - PKU causes many seemingly unrelated symptoms ranging from mental retardation to hair/skin changes

29. What does primase do
Phosphorylation excess glucose to sequester it - liver becomes blood glucose buffer
Tendency for certain alleles at 2 linked loci to occur together more often than expected by chance - varies is different populations
Oral uridine administration
Makes RNA primer on which DNA poly III can initiate replication

30. peripheral neuropathy - developmental delay - optic atrophy - glopoid cells
Adipse tissue stores - keton bodies become the main source of energy fo the brain and heart - after these are depleted - vital protein degradation accelerates - leading to organ failure and death
Rickets in kids - bending bones - osteomalacia in adults - hypocalcemia tetany - breast milk has dec vit D (supplement in dark skinned patients)
Phosphenolpyruvate to pyruvate catalyzed by pyruvate kinase
Krabbes - galactocerebrosidase - galactocerebroside - AR

31. What enzyme degrades a small amount of glycogen in lysosomes
Convulsions - hyperirritability - peripheral neuropathy - deficiency inducible by INH and oral contraceptives - sideroblastic anemais
Fibrofatty replacement of muscle - cardiac myopathy
Evident in first few days of life - can present last onest - excess carbamoyl phosphate converted to orotic acid - orotic acid in blood and urine - dec BUN and symptoms of hyerpammonemia
Alpha 1 -4 glucosidase

32. What is proteasomal degredation
AR
Attachment of ubiquitin to defective proteins tag them for breakdown
FISH
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)

33. What is a silent mutation
Trisomy 18 - severe mental retardation - rocker bottom feet - micrognathia - low set ears - clenched hands - prominent occiput - congenital heart disease - death usually within the first year
Same AA - often base change in 3rd position of codon (tRNA wobble)
Nonsense > missense > silent
Miscarriage - stillbirth - chromosomal imbalance (down - patau)

34. What happens in hyperammonemia
AR disorder characterized by defective neutral amino acid transporte on renal and intestinal epith cells
Glycine
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible
Depletes alpha - ketoglutarate leading to inhibition of TCA cycle - tremor slurring of speech - somnolence - vomiting - cerebral edema - blurring of vision

35. What are the findings in Down's syndrome
Cystathionine synthase def - dec affinity of cystathionine synthase for pyridoxal phosphate - homocystein methyltransferase def
Phenylalanine
Mental retardation - flat facies - prominent epicanthal folds - simian crease - gap between 1st 2 toes - duodenal atresia - congenital heart disease (ASD) - inc risk of All and Alzheimers
Fructose 1 -6 bisphosphate

36. How many ATP are created by aerobic metobolism of glucose in muslce via what shuttle
Carbomoyl phosphate synthetase I
30 - glycerol -3- phosphate shuttle
Depleted for gluconeogenesis staling the TCA cycle and shunting glucose and FFA to production of ketone bodies
Coarse facial features - clouded corneas - restricted joint movements - high plasma levels of lysosomal enzymes - often fatal in childhood

37. What is maternal PKU
Polyneuritis - symmetrical muscle wasting
Lack of proper dietary therapy during pregnancy leading to microcephaly - mental retardation growth retardation - congenital heart defects
HMG- CoA synthase
Pantothenate - essential component of CoA - a cofactor for acyl transfers and fatty acid synthase

38. What are the results of unbalanced translocation
Tay- Sachs - hexosaminidase A - GM2 ganglioside - AR
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
Tall with long extremeties - pectus excavatum - hyperextensive joints - arachnodactyly
Miscarriage - stillbirth - chromosomal imbalance (down - patau)

39. What is the purpose of the HMP shunt
Prokaryotic only - elongates leading strand by adding deoxnucTIDE to the 3' end. Elongates lagging strand until it reaches primer of preceeding fragment. 3' to 5' exonuclease activity 'proofreads' each added nucTIDE
Dec DNA - dec lymphos leads to SCID
Provide a source of NADPH from an abundantly available glucose 6P - create ribose for nucleotide synthesis and glycolytic intermediates
Receptor tyrosine kinases - protein phosphatase - takes phosphate off glycogen phosphorylase kinase inactivating it

40. How do permanent cells grow and regenerate and What are examples of permanent cells
GTP
Remain in G0 - regenerate from stem cells - neurons - skeletal/cardiac muscle - RBCs
MRNA - tRNA
Tendency for certain alleles at 2 linked loci to occur together more often than expected by chance - varies is different populations

41. How many nucTIDEs is a tRNA and What does the secondary sturcture form
AMP - fructose 2 -6 BP
2 rings
75 to 90 - cloverleaf
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns

42. Giving folate during early pregnancy is important to prevent what birth defects
Neural tube
Glycogenolysis to form glucose
Galactitol - galactose appears in blood and urine - can cause infantile cataracta - AR
2 -4 DNP - aspirin

43. congenital deficiency of homogentisic acid oxidase in the degradative pathway of tyrosine to fumarate leading to dark connective tissue - brown pigmented sclera - urine turns black on standing - dz and worst complication
B12 and folate
Liver and leafy veggies
Alkaptonuria - may have debiliating arthralgias
Presence of both nl and mutated mtDNA resulting in mitochondrial inherited disease

44. Which carbon bears the triphosphate and the energy source for bond formation

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45. What two amino acids are required druing periods of growth and why
B(1 - 2 - 3 - 5 - 6 - 12) C - biotin and folate (B12 and folate are stored)
They yield only acetyl - CoA equivalents
Malate - aspartate shuttle or the glycerol 3 phosphate shuttle
Arg and his inc in histones Which bind negatively charged DNA

46. inc glycogen in muscle but can't break it down - painful muscle cramps - myglobinuria with strenuous exercise - dz and enzyme

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47. What inhibits the carnitine shuttle
Dopamine beta hydroxylase
Malonyl coa
Methionine encode by only 1 codon (AUG)
Orotate precursor - with PRPP added later

48. What are the irreversible enzymes of gluconeogenesis
Pyruvate carboxylase - PEP carboxykinase - fructose 1 -6 biphosphatase - glucose 6 phosphatase
CAG - 4
Carnitine acyltransferase I
Glycolysis and aerobic respiration

49. How do aminoglycosides work
Makes RNA primer on which DNA poly III can initiate replication
By inhibiting formation of the initiation complex and cause misreading of mRNA
CarTWOlage
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage

50. What metabolic rxns occur in both the cytoplasm and mitochondria
HMG- CoA reductase
Y shaped region along the DNA template where leading nad lagging strands are synthesized
FAP
Heme synthesis - urea cycle and gluconeogenesis - HUGs take two