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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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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What are purines made from
Binds to LDL receptor - mediates VLDL secretion
IMP precursor
Nature and severity of phenotype vary from 1 individual to another - NF type 1
NAD+

2. What does primase do
Core proteins
B12 and folate
Makes RNA primer on which DNA poly III can initiate replication
DNA

3. bilateral - massive enlargement of of kidneys due to multiple large cysts
Consesus sequenec of base pairs
Change resulting in early stop codon
Cofactor for LPL
ADPKD

4. Where is fructose 1 -6 bisphosphatase found and What does it do
Tryptophan excretion in urine and dec absorption from the gut leading to pellagra
Griseofulvin
Cytosol - F 1 -6 BP to fructose 6 Phosphate
Connective tissue

5. What is the RDE of the HMP shunt
Removal of N or C termal propeptides from zymogens to generate mature proteins
Glucose 6 phosphate dehydrogenase (G6PD)
Absence of galactose 1 phosphate uridyltransferase - accumulation of toxic substances leads to failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation
Isocitrate dehydrogenase

6. What are pyrimidines made from
Adenosine to inosine
Orotate precursor - with PRPP added later
Purines= A - G pyrimidine = C - T (U)
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels

7. Where are the secretory proteins made and N- linked oligosaccharide addtions put on proteins
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
Dec in alpha ketoacid dehydrogenas leading to blocked degredation of branches amino acids like Ile - Leu - and Val - severe CNS defects mental retardation and death
RER
Dermatitis - glossitis - and diarrhea

8. antbiotic controlled promoter to induciblly manipulate genes at specific developmental points
Cre - lox system
MRNA - tRNA
2 -4 DNP - aspirin
Transfers methyl units

9. Delivers hepatic cholesterol to peripheral tissues - formed by LPL modification of VLDL in the peripheral tissue - taken up by target cells via RME
LDL
Cobalamin - cofactor of homocysteine and methyltransferase - methylmalonyl CoA mutase
Carnitine acyltransferase I
Change resulting in early stop codon

10. What does hepatic TG lipase do
Glucose 6 phosphate dehydrogenase (G6PD)
Deamination
Degradation of TG remaining in IDL
Schilling test

11. In which state is FBPase -2 active
5' to 3'
Foliage - small reserve in liver - eat green leaves
Fasting
Targets the proteins for lysosome

12. What is the breakdown product of epi
Sucrose = glucose + fructose - lactose = glucose + galactose
Infection - free radicals generated by inflammatory response
Metanephrine
Ornithin transcarbamoylase def - x linked recesssive - other urea cycle enzymes defs are autosommal recessive

13. What is the most abundant protein in the body
Alkaptonuria - may have debiliating arthralgias
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Tendency for certain alleles at 2 linked loci to occur together more often than expected by chance - varies is different populations
Collagen

14. What is pseudohypertrophy in the calf a result of - and What are the cardiac manifestations
Catabolic processes to carry reducing equivalents away as NADH
DTMP
Limit protein diet - benzoate or phenylbutarate (both bind amino acids leading to excretion) can decrease ammonia levels
Fibrofatty replacement of muscle - cardiac myopathy

15. Which direction does dynein go
Post to neg
Neimann - pick - sphingomyelinase - sphingomyelin - AR
Change resulting in misreading of all nucleotides downstream - usually resulting in a truncated nonfxnal protein
CG- 3 > AT-2 - More CG content - melting point goes up

16. I g fat = ? Kcal
Sucrose = glucose + fructose - lactose = glucose + galactose
Nine
Elastase - inhibited by alpha1 antitrypsin
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

17. What is axonemal dynein
ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets
Change resulting in misreading of all nucleotides downstream - usually resulting in a truncated nonfxnal protein
Mitochondria
FISH

18. What is made fir rNucleotides or deoxyrNucleotides and what enzyme is necessary to convert one to the next
Ribos first then deoxyribos with ribonucleotide reductase
One
Phenylalanine hydroxylase - tetrahydrobiopterin cofactor
Inhibits acetaldehyde dehydrogenase and contributes to hangover symptoms

19. Why is albinism inheritnace varialbe due to...
Locus heterogeneity - ocular albinism is x- linked recessive
RNA poly II
Huntingtons
Glucose 6P to CO2 - 2NADPH - ribulose 5P - G6PD - rate limiting step

20. What other inflammatory process can induce a hemolytic anemia in NADPH defieicnt patients
GTP hydrolysis - initiation factors assemble 40S ribosomal subunit with initiator tRNA and are released with mRNA and ribosomal subunit assemble with the complex
Infection - free radicals generated by inflammatory response
G6PD
Scrutinizes - hydrolyzes the bond

21. What does a carboxylase do
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
Adds 2 carbon with the help of biotin
Inc insulin - dec cAMP - dec PKA
Pyruvate to oxaloacetate (3C to 4C)

22. What substances inhibit phosphofructokinase -1
Read from a fixed starting point as a continuous sequence of bases
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 - citrate
AR disorder characterized by defective neutral amino acid transporte on renal and intestinal epith cells

23. What are the names and sources of the two types of vit D found in nature
MEN - 2A and 2B with ret gene
D2 = ergocalciferol - ingested from plants D3 = cholecalciferol - ingested from milk - formed in sun exposed skin
Pompe's lysosomal alpha 1 -4 glucosidase (acid maltase) (pompe trashes the pump; heart - liver - muscle)
HGPRT - defective purine salvage - excess uric acid production

24. What is the RDE of glycogen synthesis
Glycogen synthase
Adds an inorganic phosphate onto substrate without using ATP
Targets the proteins for lysosome
Stop codon is recognized by release factor - and completed protein is released from ribosome

25. What inhibits the carnitine shuttle
NH2-(C=O) - NH2 one NH2 from ammonia the C=O from CO2 - and the other NH2 from aspartate
Malonyl coa
HDL
Unmethylated - newly synthesized - HNPCC

26. What is the hardy weinber heterozygote prevalence
2pq
CTG
UGA - UAA and UAG
Free ribosomes

27. 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
Makes RNA primer on which DNA poly III can initiate replication
Alkaptonuria - may have debiliating arthralgias
Flagella - cilia - mitotic spindles
NAD+

28. What is the active form of vit D
Catabolic processes to carry reducing equivalents away as NADH
1 -25 OH2 D3 = calcitriol
Four
Absence of galactose 1 phosphate uridyltransferase - accumulation of toxic substances leads to failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation

29. Inhibition of thymidilate synthase and and DHFR lead to decrease In what substance
Nonsense > missense > silent
Orotic acid phosphoribosyltransferase or orotidine 5'- phosphate decarboxylase
DTMP
Sulfation

30. What does SAM do
Hypoglycemia
Must be both activated and inactivated for cell cycle to progress
Transfers methyl units
Arg and his inc in histones Which bind negatively charged DNA

31. Why enzyme breaks down elastin and what enzyme inhibits it
Propionyl - CoA to methylmalonyl - CoA (3C to 4C)
FMR1 gene - methylation - associated with chromosomal breakage
Presence of both nl and mutated mtDNA resulting in mitochondrial inherited disease
Elastase - inhibited by alpha1 antitrypsin

32. How many rings do pyrimidines have
1 ring
Locus heterogeneity - ocular albinism is x- linked recessive
Constitutive - random insertion of gene into mouse genome and conditional - targeted insertion or deletion of gene through homologous recombination with mouse gene
X- linked recessive

33. What form of amino acids are found in proteins
L form
3 NADH - 1 FADH2 - 2 CO2 - 1 GTP = 12 ATP (x2 per glucose)
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
Methionine encode by only 1 codon (AUG)

34. What substances induce phosphofructokinase
AMP - fructose 2 -6 BP
Defect in fibrillin
Inc glucagon - inc cAMP - inc PKA
They yield only acetyl - CoA equivalents

35. Which direction does kinesin go
Neg to pos
DTMP
Anchor muscle fibers - primarily in skeletal and cardiac muscle
BOne

36. What is locus heterogeneity and give an example
Glucose 6P to CO2 - 2NADPH - ribulose 5P - G6PD - rate limiting step
Basement membrane or basal lamina
Mutations at different loci can produce the same phenotype - marfans - MEN 2B - homocystinuria; all cause marfinoid habitus - also albinism
Infection - free radicals generated by inflammatory response

37. What happens on the nonoxidative arm of the HMP shunt and What is the key enzyme and cofactor
APKD1 on chromosome 16
Lack of tyrosinase (no melanin) AR ordefective tyrosine transporters (less tyrosine) - can results in lack of migration of NC cells
Ribulose 5P to ribose 5P - G3P and F6P - transketolase and B1
Excess NADH shunts oxaloacetate to malate (backwards) stalling the TCA and shunting glucose and FFA to ketone body production

38. What is the rate determining enzyme (RDE) of glycolysis
Phosphofructokinase 1
Malate - aspartate shuttle or the glycerol 3 phosphate shuttle
African Americans and Asians
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver

39. What does desmin stain for
Muscle
LPL def - or altered apoCII - elevated TG and cholesterol - causes pancreatitis - hepatosplenomegaly and eruptive/pruritic xannthomas - no risk of atherosclerosis
Convulsions - hyperirritability - peripheral neuropathy - deficiency inducible by INH and oral contraceptives - sideroblastic anemais
Hereditary spherocytosis

40. What does arsenic do and What are th results of poisoning
RRNA
Infection - free radicals generated by inflammatory response
Cystathionine synthase def - dec affinity of cystathionine synthase for pyridoxal phosphate - homocystein methyltransferase def
Inhibits lipoic acid - vomiting - rice water stools - garlic breath

41. What happens in the first stage of collagen synthesis - and Where does it happen
Oxidizes substrate
CO2 + NH4 needs carbamoyl phosphate synthase I - in the mitochondria
Gamma carboxylation of glutamic acid residues on various proteins concerned with blood clotting - synthesized in intestinal flora
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)

42. What tissues have both enzymes of sorbitol metabolism
PMNs
Liver - ovaries - seminal vesicles
Riboflavin - cofactor in oxidation and reduction (FAD and FMN are derived from riboflavin)
Paclitaxel

43. What leads to the deletion of the dystrophin gene in duchenne's muscular dystrophy
Fructose 1 -6 bisphosphate
Base + ribose
X linked frame shif mutation
Hereditary hemorrhagic telangiectasia (Osler - Weber - Rendu syndrome)

44. What does degenerate/rundant genetic code refer to...
Excess ATP - dATP - feeback inhibits ribonucleotide reductase - no DNA synthesis
Dermatitis - alopecia - enteritis
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
More than 1 codon may code for the same amino acid

45. Which are the acidic amino acids
Inc NADH/NAD ratio in liver - causing diversion of pyruvate to lactate and OAA to malate - inhibiting gluconeogenesis and stimulating fatty acid synthesis. Leads to hypoglycemia and hepatic fatty liver change seen in chronic EtOH users
Asp and Glu
Tyrosine
Each codon specifies only 1 amino acid

46. What feedback inhibits hexokinase
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
Blood - bone marrown - amniotic fluid - placental tissue
ATP and methionine
Glucose -6 phosphate

47. What is the activated carrier for electrons
Read from a fixed starting point as a continuous sequence of bases
Bone - skin - tendon - dentin - fascia - cornea - late wound repair
NADH - NADPH - FADH2
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

48. Delivers dietary TGs to peripheral tissues - delivers cholesterol to liver in the form of remnants - mostly depleted of TGs - secreted by intestinal epith cells
Glycolysis - fatty acid synthesis - HMP shunt - protein synthesis (RER) - steroid synthesis (SER)
Ubiquitous - low Km - high affinity - low capacity low Vmax - uninduced by insulin
Inc CPK and muscle biopsy
Chylomicrons

49. Which antifungal drugs work on microtubules
Griseofulvin
Glucose -6 phosphate
They yield only acetyl - CoA equivalents
Isocitrate dehydrogenase

50. What is loss of heterozygosity and give an example
Glutamine PRPP amidotransferase
5' of the incoming nucleotide
Cystic medial necrosis of aorta leading to aortic incompetence and dissecting aortic aneurysms - floppy mitral valve - subluxation of lenses
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