Test your basic knowledge |

Biochemistry

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 does apoB100 do
Alpha 1 -4 glucosidase
Inability to transport LCFAs into mitochondria results in toxic accumulation causing weakness - hypotonia - hyperketotic hyperglycemia
Mutated dystrophin gene - less severe - adolescence
Binds to LDL receptor - mediates VLDL secretion

2. pyruvate carboxylase catalyzes what rxn
Pyruvate to oxaloacetate (3C to 4C)
Active secretion in lungs and GI - reabsorbs in skin
Cartilage - hyaline - vitreous body - nucleus pulposus
Arg and his inc in histones Which bind negatively charged DNA

3. facial lesions - hypopigmented 'ash leaf spots -' cortical and retinal hamartomas - seizures - mental retardation - renal cysts - renal angiomyolipomas - cardiac rhabdomyomas - inc risk of astrocytomas
17 - 17 letters in von Recklinghausen
Type II
Tuberous sclerosis
Hydroxyurea - inhibits ribonucleotide reductase - 6 MP - blocks de novo purine synthesis - 5 FU inhibits thymidilate synthase - MTX - inhibits DHFR - Trimethroprin inhibits bacterial DHFR

4. metaphse chromosomes are stained - ordered and numbered according to morphology - size - arm length ratio - banding pattern
Karyotyping
Flank pain - hematuria - HTN - progressive renal failure
Dec AFP - inc betahCGH - dec estradiol - inc inhibin - inc nuchal translucency on US
Binds to LDL receptor - mediates VLDL secretion

5. What bone disorder has x linked dominant inheritance
Malabsorption (sprue - enteritis) lack of intrinsic factor from pernicious anemia - gastric bypass surgery or absence of terminal ileum as in Crohns
Hypophophatemia rickets - vit D resistant ricketts - inc wasting of phosphate in proximal tubule - rickets like presentation
GTP hydrolysis - initiation factors assemble 40S ribosomal subunit with initiator tRNA and are released with mRNA and ribosomal subunit assemble with the complex
Pyruvate carboxylase - PEP carboxykinase - fructose 1 -6 biphosphatase - glucose 6 phosphatase

6. Where is pyruvate carboxylase found - What does it do - What does it require amd What activates it
In mitochondria - pyruvate to oxaloacetate - requires biotin - ATP - activated by acetyl coA
Four
Degradation of TG stored in adipocytes
APC on chromosome 5

7. What can vit B3 be used to treat
Anchor muscle fibers - primarily in skeletal and cardiac muscle
Hyperlipidemia
Q -
No

8. Which antifungal drugs work on microtubules
HMP shunt
RNA
Griseofulvin
Enhancers

9. What are the mRNA stop codons
Diphyllobothrium latum
P+q = 1
UGA - UAA and UAG
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels

10. What does DNA ligase do
Alpha1 antitrypsin
Paclitaxel
Histidine
Seals.

11. A small proportion of Down syndrome is due to What two genetic events
Mental retardation - seizures - ataxia - inappropriate laughter - deletion of normally active maternal allele
Elastase - inhibited by alpha1 antitrypsin
Converted to THF - a coenzyme for one - carbon transfer/methylation reactions - important for synthesis of nitrogenous bases in DNA and RNA
Robertsonian translocation and mosaicism

12. What is the treatment for dec affinity of cystathionine synthase for pyroxidal phosphate
4 under the floor
Transfers methyl units
IMP precursor
Inc vit B6

13. Why enzyme breaks down elastin and what enzyme inhibits it
Elastase - inhibited by alpha1 antitrypsin
Vit K antagonist
Sulfation
Backup of substrate (pyruvate and alanine) resulting in lactic acidosis - congenital or acquired from thiamine def in EtOH - neuro defects

14. What are the glucogenic/ketogenic amino acids
5' of the incoming nucleotide
Malonyl coa
Ile - phe - thr - trp
Base + ribose + phosphate (3' -5') phosphodiester bond

15. The pyruvate dehydrogenase complex serves In what reaction: products
Acetly- CoA - CO2 - NADH
Sulfation
Adenylyl cycle - inc cAMP - inc PKA - glycogen phosphorylase kinase activated - glycogen phosphoylase active - glycolysis
Achondroplasia

16. What do def in in enzymes of gluconeogenesis cause
Inhibits RNA polymerase II - found in death cap mushrooms
Avidin
Phenylalanine
Hypoglycemia

17. In which state is FBPase -2 active
Provide a source of NADPH from an abundantly available glucose 6P - create ribose for nucleotide synthesis and glycolytic intermediates
Phenylalanine hydroxylase
MRNA - tRNA
Fasting

18. What is the amino acid precursor for histamine
Foliage - small reserve in liver - eat green leaves
Hereditary defect of renal tubular amino acid transporter for cystein - ornithine - lysine and arginine in PCT
Histidine
2 pyruvate - 2ATP - 2NADH - 2H+ - 2H2O

19. What is pseudohypertrophy in the calf a result of - and What are the cardiac manifestations
Phosphofructokinase 1
Nine
Inhibits acetaldehyde dehydrogenase and contributes to hangover symptoms
Fibrofatty replacement of muscle - cardiac myopathy

20. What collagen type is most frequently affected in ehlers danlos and What are common complications
III - joint dislocation - anuerysms - organ rupture
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible
Differences in phenotype depend on whether the mutation is of maternal or paternal origin - prader - willi and angelman's syndrome
Oxidative and nonoxidative - no ATP produced or used

21. Where are FADH2 electrons transferred to...
Collagen
Adenylyl cycle - inc cAMP - inc PKA - glycogen phosphorylase kinase activated - glycogen phosphoylase active - glycolysis
Comlex II
Cheilosis - inflammation of lips - scaling and fissures at the corner of the mouth - corneal vascularization

22. What are the blood glucose levels maintained by for days 1-3
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Acetoacetate and beta hydroxybutyrate
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)
Locus heterogeneity - ocular albinism is x- linked recessive

23. What is the defect in II A familial hypercholesterolemia
AD absent of dec LDL receptors causes accelerated atherosclerosis - achilles xanthomas and corneal arcus - increase LDL and elecated cholesterol
Huntingtons
Catalase positive (catalase neg produce H2O2 the cell can use) like S. aureus or aspergillus
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

24. What apolipoproteins are on chylomicrons
Proton gradient
Conversion of NE to epi
Inhibits RNA polymerase II - found in death cap mushrooms
B48 - AIV - CII - E

25. What is the function of Zinc
Fibroblast
Glycolysis - fatty acid synthesis - HMP shunt - protein synthesis (RER) - steroid synthesis (SER)
Directly inhibit the Na/K pump which leads to indirect inhibition of Na/Ca exchange - inc calcium inside the cell - inc cardiac contractility
Essential for the activity of over 100+ enzymes - important in the formatio of zinc fingers -

26. What is the order of severity for the different types of mutations
Coenzyme A - lipoamide
In cytosol - oxaloacetate to phosphenolpyruvate - requires GTP
Nonsense > missense > silent
Neurons

27. What is the wernicke - korsakoff clinical picture
Semiconservative - continuous and discontinuous strands (okazaki fragments)
Confusion - opthalmoplegia - ataxia - confabulation - personality changes and memory loss
Acetyl - CoA carboxylase (ACC)
HGPRT - defective purine salvage - excess uric acid production

28. Inhibition of thymidilate synthase and and DHFR lead to decrease In what substance
Disorder of aromatic amino acid metabolism
DTMP
Essential for the activity of over 100+ enzymes - important in the formatio of zinc fingers -
Vit K antagonist

29. What do albinism - ARPKD - CF - glycogen storage diseases - hemochromatosis - mucopolysaccharidoses (except Hunters) PKU - sickle cell - sphingolipodoses (except Fabrys) thalassemias have in common
SAM
Neuralgia
L form
Autosomal recessive diseases

30. What is variable expression and What is an example
Actin and myosin
Hydroxyurea - inhibits ribonucleotide reductase - 6 MP - blocks de novo purine synthesis - 5 FU inhibits thymidilate synthase - MTX - inhibits DHFR - Trimethroprin inhibits bacterial DHFR
Inhibits acetaldehyde dehydrogenase and contributes to hangover symptoms
Nature and severity of phenotype vary from 1 individual to another - NF type 1

31. How do aminoglycosides work
By inhibiting formation of the initiation complex and cause misreading of mRNA
Blood - bone marrown - amniotic fluid - placental tissue
TRNA
Tyrosine

32. antbiotic controlled promoter to induciblly manipulate genes at specific developmental points
Microarrays
Cre - lox system
Alpha1 antitrypsin
Ile - phe - thr - trp

33. What other complex is similar to the pyruvate dehydrogenase complex in that it has the same co - factors and generates succinyl - CoA
Lysine and arginine
Alpha - ketoglutarate dehydrogenase complex
PFK - rate limiting enzyme
Marasmus - muscle wasting

34. This is the site where negative regulators bind
HMG- CoA reductase
Inc insulin - dec cAMP - dec PKA
Cori's - debranching enzyme alpha 1 -6 glucosidase - gluconeogenesis intact
Silencers

35. What amino acid makes up most of the octamer
Reticulin - skin - blood vessels - uterus - fetal tissue - granulation tissue
Lysine and arginine
B100 and E
For proteins and lipids from ER to plasma membrane - lysosomes and secretory vesicles

36. What are pyrimidines made from
Particular sequence of DNA where replicatino begins - may be single of multiple
Nissl body - enzyme and NTs
Confusion - opthalmoplegia - ataxia - confabulation - personality changes and memory loss
Orotate precursor - with PRPP added later

37. What is the breakdown product of epi
Metanephrine
Griseofulvin
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
ATP and methionine

38. What is the RDE of fatty acid oxidation
Carbomoyl phosphate synthetase II
NADH - NADPH - FADH2
Met - val - arg his
Carnitine acyltransferase I

39. What does vit E def cause
Inc fragility of RBC - hemolytic anemia - muscle weakness - posterior column and spinocerebellar tract demyelination
HMG- CoA reductase
SAM
Intermediate filaments

40. Type IV BM
Excess NADH shunts oxaloacetate to malate (backwards) stalling the TCA and shunting glucose and FFA to ketone body production
4 under the floor
NF2 on chromosome 22
Wrinkles and acne

41. What do DNA topoisomerases do
AR
Cre - lox system
Creat a nick in the helix to relieave supercoils created during replication
Defect in fibrillin

42. peripheral neuropathy - developmental delay - optic atrophy - glopoid cells
Oral uridine administration
Cori's - debranching enzyme alpha 1 -6 glucosidase - gluconeogenesis intact
Free ribosomes
Krabbes - galactocerebrosidase - galactocerebroside - AR

43. What are the symptoms of vit A excess
More than 1 codon may code for the same amino acid
Athralgias - fatigue - headaches - skin changes - sore throat - alopecia
Inhibit DNA gyrase specific for prokaryotic topoisomerase
Malabsorption and steatorrhea (ADEK)

44. How does patients present with ADPKD
Lack of tyrosinase (no melanin) AR ordefective tyrosine transporters (less tyrosine) - can results in lack of migration of NC cells
Sulfation
Flank pain - hematuria - HTN - progressive renal failure
Phosphorylation excess glucose to sequester it - liver becomes blood glucose buffer

45. How is vit D stored
Met - val - arg his
Regulatory proteins that control cell cycle events; phase specific; activate CDKs
25OHD3
Thiamine - in thiamine pyrophosphate a cofactor for pyruvate dehydrogenase (glycolysis) - alpha ketoglutarate dehydrogenase (TCA cycle) - transketolase (HMP shunt) - and branched - chain AA dehydrogenase

46. Synthesis of vit B3 requires what other vitamin
B6
Aberrant 3rd and 4th branchial arches causing 22q11 deletion - cleft palate - abnl facies - thymic dysplasia - cardiac defects - hypocalcemia secondary to parathyroid aplasia
Enter G1 from G0 when stimulated - hepatocytes and lymphocytes
Cyclin dependent kinases;constitutive and inactive

47. What liberates glucose from glucose 6 P
Actin and myosin
Glycolysis and aerobic respiration
NADH - NADPH - FADH2
Glucose 6 phosphatase

48. What is uniparental disomy
De novo pyrimidine synthesis and urea - ornithine transcarbamoyl def in the urea cycle leads to a build of CP - then converted to orotic acid in pyrimidine synthesis pathway
Mental retardation - seizures - ataxia - inappropriate laughter - deletion of normally active maternal allele
1 -25 OH2 D3 = calcitriol
Offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent

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

50. What is the function and name of vit B6
Pyroxidine - converted to pyroxidine phosphate a cofactor used in transamination - decarboxylation - glycogen phosphorylase - cystathionine synthesis and heme synthesis - required for synthesis of niacin and tryptophan
B100 and E
Cytosol
Macrocytic - megaloblastic anemia - no neurologic sx - most common vit def in the US - seen in EtOH and pregs