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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 residues are hydroxylated in step 2 of collagen synthesis - and What does this require
CFTR gene - 7 - Phe 508
Impaired glucose breakdown leading to ATP depletion; highly affected aerobic tissues like brain and heart affected first
Dopa decarboxylase
Proline and lysine - vit C

2. What substance inside the cell reduces glutatione
Microtubules
DTMP
NADPH
25OHD3

3. What happens in vit D excess
B48 - AIV - CII - E
ATP and alanine
Protein kinase A
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage

4. What trinucleotide repeat in Huntingtons and what chromosome is it found on...
DsRNA promotes degradation of target mRNA knocking down gene expression
Leu - lys
Oxidative and nonoxidative - no ATP produced or used
CAG - 4

5. What defects characterize velocardiofacial syndrome
B100 and E
Palate - facial and cardiac defects
Antibiotic use or excessive ingestion of raw eggs
Cytosol - F 1 -6 BP to fructose 6 Phosphate

6. what disease can cause pellagra
Modifies N- oligosaccharides
Foliage - small reserve in liver - eat green leaves
Aminoacyl - tRNA binds A site - ribosomal rRNA catalyzes peptide bond formation - transfers growing peptide to AA in A site - ribosome advances 3 nucTIDE toward 3' end of RNA - moving peptidyl RNA to P side
Hartnup disease - dec tryptophan absoprtion - malignant carcinoid syndrome (inc tryptopha metabolism) and INH (dec vit B6)

7. depression - progressive dementia - choreiform movements - caudate atrophy and dec levels of GABA and ACH in the brain
Huntingtons
Lysine and leucine
In mitochondria - pyruvate to oxaloacetate - requires biotin - ATP - activated by acetyl coA
Meiotic nondisjunction of homologous chromosomes (associated with advanced maternal age) leading to trisomy 21

8. What shape does the RNA generate during splicing and why?
HGPRT - defective purine salvage - excess uric acid production
Schilling test
Four
Lariat shape in order and remove intron precisely and join 2 exons

9. What is the activated carrier for methyl groups
Common metabolites like pyruvate and acetyl CoA and excess NH4+ converted to urea and exreted
Ribulose 5P to ribose 5P - G3P and F6P - transketolase and B1
SAM
Paclitaxel

10. What is the TX for PKU
PFK - rate limiting enzyme
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
Dec phenylalanine (contained in aspartame - Nutrasweet) inc tyrosine in diet
Phenytoin - MTX - and sulfonamides

11. What is the results of vit B1 def
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
B48 - AIV - CII - E
Night blindness - dry skin
Impaired glucose breakdown leading to ATP depletion; highly affected aerobic tissues like brain and heart affected first

12. What shuttle is used in fatty acid degredation and What does it move and From where to where
Connective tissue
Carnitine shuttle - acyl - coa from cyto to mito
Epithelial cells
Reads usual codon but inserts wrong AA

13. spheroid RBCs due to spectrin or ankyrin defect - hemolytic anemia - inc MHCH - splenectomy is curative
1 gene had >1 effect on an individuals phenotype - PKU causes many seemingly unrelated symptoms ranging from mental retardation to hair/skin changes
Hereditary spherocytosis
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
Semiconservative - continuous and discontinuous strands (okazaki fragments)

14. What are the results of CF on male fertility
Must be both activated and inactivated for cell cycle to progress
Kidney - ears - eyes
40 - 60 - 80
Males are infertile due to bilateral absence of vas deferens

15. Which bond is stronger AT or CG and why? What is the laboratory consequence of this?
Fasting
CG- 3 > AT-2 - More CG content - melting point goes up
Inhibits RNA polymerase II - found in death cap mushrooms
Familial hypercholesterolemia - hyperlipidemia type IIA

16. What is the treatment for cystathionine synthase def
Acetyl - CoA
Fed
Dec methionine - inc cystiene - inc B12/folate
2 -4 DNP - aspirin

17. What does vit C def cause
2 -4 DNP - aspirin
FMR1 gene - methylation - associated with chromosomal breakage
Pyruvate dehydrogenase - ATP - NADH - acetyl - CoA
Scurvy - swollen gums - bruising - hemarthrosis - anemia - poor wound healing - weakened immune response

18. What are the mRNA stop codons
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
UGA - UAA and UAG
Enhancers
Consesus sequenec of base pairs

19. What does the golgi do to sugars in proteoglycans and of selected tyrosine on proteins
FAP
Phenylketones in urine
Sulfation
30 - glycerol -3- phosphate shuttle

20. Acetyl - CoA carboxylase catalyzes what rxn
Acetyl - CoA to malonyl - CoA (2C to 3C)
Diphyllobothrium latum
Achondroplasia
AMP - fructose 2 -6 BP

21. Which enzyme involved in RNA synthesis does not require a template
Poly A polymerase - signal is AAUAA
Sever atherosclerotic disease early in life - and tendon xanthomas on the achilles - MI may develop before 20
Cleft palate - cardiac abnl - pregs test
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis

22. What happens in carnitine def
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
Neuralgia
Inability to transport LCFAs into mitochondria results in toxic accumulation causing weakness - hypotonia - hyperketotic hyperglycemia
Heme synthesis - urea cycle and gluconeogenesis - HUGs take two

23. Mediates reverse cholesterol transport from periphery to liver - acts as respository for apoC an apoE - secreted from both liver and small intestine
1 kind with multiple subunits
HDL
Glucose 6 phosphate dehydrogenase (G6PD)
Aldolase B - AR - fructose 1P accumulates causing a dec in availabel phosphate which inhibts glycogenolysis and gluconeogenesis leading to hypoglycemia - cirrhosis - jaundice and vomiting

24. What is the fxn of vit K
F16BP
Hepatic overproduction of VLDL causing pancreatitis - elvelated TGs and VLDL
Gamma carboxylation of glutamic acid residues on various proteins concerned with blood clotting - synthesized in intestinal flora
N to C

25. What step begins the urea cycle and What is the enzyme needed - Where does it happen
Orotate precursor - with PRPP added later
RRNA
Galactitol - galactose appears in blood and urine - can cause infantile cataracta - AR
CO2 + NH4 needs carbamoyl phosphate synthase I - in the mitochondria

26. What is the hardy weinber heterozygote prevalence
Cytosol
Adds an inorganic phosphate onto substrate without using ATP
Elastase - inhibited by alpha1 antitrypsin
2pq

27. How is ATP used by the cell
Proton gradient
RRNA
ATP hyrdolysis couple to energetically unfavorable rxns
Heterochromatin = HighlyCondensed

28. What causes maple syrup urine disease and What does it lead to...
Tendency for certain alleles at 2 linked loci to occur together more often than expected by chance - varies is different populations
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
Impaired glucose breakdown leading to ATP depletion; highly affected aerobic tissues like brain and heart affected first
Schilling test

29. How does chloramphenicol work
Hypophophatemia rickets - vit D resistant ricketts - inc wasting of phosphate in proximal tubule - rickets like presentation
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
Inhibits 50S peptidyltransferase
Infection - free radicals generated by inflammatory response

30. 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
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
By inhibiting formation of the initiation complex and cause misreading of mRNA
Acetyl - CoA
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light

31. What is the physiologic role of dystrophin
Fasting
Anchor muscle fibers - primarily in skeletal and cardiac muscle
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
No - its non homologous

32. What substance in egg whites binds biotin
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
Acetyl - CoA
Avidin

33. What does a phosphatase do
Removes phosphate group from substrate
Cystathionine synthase def - dec affinity of cystathionine synthase for pyridoxal phosphate - homocystein methyltransferase def
Q -
HMG- CoA (HMG- CoA to mevalonate

34. How does patients present with ADPKD
Arg - lys - his - arg is most basic - has has no charge at body pH
Semiconservative - continuous and discontinuous strands (okazaki fragments)
Flank pain - hematuria - HTN - progressive renal failure
Glucose -6 phosphate

35. What is the amino acid precuror for creatine - urea and nitric oxide
Aberrant 3rd and 4th branchial arches causing 22q11 deletion - cleft palate - abnl facies - thymic dysplasia - cardiac defects - hypocalcemia secondary to parathyroid aplasia
Base + ribose + phosphate (3' -5') phosphodiester bond
Arginine
Elastase - inhibited by alpha1 antitrypsin

36. What step of uric acid synthesis does xanthine oxidase catalyze
Creat a nick in the helix to relieave supercoils created during replication
Nature and severity of phenotype vary from 1 individual to another - NF type 1
X- linked recessive
Hypoxanthine to xanthing and xanthine to uric acid

37. What does NADPH oxidase deficiency result in and why
Hepatic glycogenolysis >> hepatic gluconeogenesis > adipose release of FFA
Chronic granulomatous disease - no respiatory burst - no formatino of ROS
G6PD
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)

38. What two enzymes are involved in EtOH metabolism
EtOH dehydrogenase and acetaldehyde dehydrogenase
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver
Hunters - iduronate sulfatase - heparan sulfate/dermatan sulfate - XR
PMNs

39. How does ethanol induce hypoglycemia
Carbomoyl phosphate synthetase II
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
Core proteins
Inc permeability of membrane causing a dec in proton gradient and inc in O2 consumption - ATP synthesis stops - but electron transport continues to produce heat

40. What is a nonsense mutation
Active secretion in lungs and GI - reabsorbs in skin
Vincritsine/vinblastine
Change resulting in early stop codon
Fructose 1 -6 bisphosphate

41. What are the fat soluble vitamins and What does their absorption depend on...
AD absent of dec LDL receptors causes accelerated atherosclerosis - achilles xanthomas and corneal arcus - increase LDL and elecated cholesterol
Backup of substrate (pyruvate and alanine) resulting in lactic acidosis - congenital or acquired from thiamine def in EtOH - neuro defects
Mitochondria
ADEK - dependent on gut (ileum) and pancreas - accumulate in fat and can cause toxicity

42. characterize mitochondrial inheritance
Tryosine hydroxylase
Griseofulvin
Transmitted only through mother - all offspring of affected females may show signs of disease
HMP shunt

43. What kind of branches do glycogen branches have
Alpha 1 -6 and alpha 1 -4
Phenylalanine
Dec phenylalanine (contained in aspartame - Nutrasweet) inc tyrosine in diet
Glucose -6 phosphate

44. Which type of chromatin is less condensed - transcriptionally active - sterically accesible
Glossitis - severe = pellagra - diarrhea - dermatitis - dementia
Euchromatin
Result from phagocytic removal of heinz bodies my macs - G6PD def
Consesus sequenec of base pairs

45. What is the amino acid precursor for GABA and glutathione
Acetoacetate and beta hydroxybutyrate
PFK - rate limiting enzyme
Skin
Glutamate

46. What happens in a B12 def
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible
Initiate chains
Exons
Neonatal hemorrhage with inc PT and PTT - but nl bleeding time - can also occur after prolonged use of broad spectrum Abx

47. Wgat substances directly inhibit mitochondrial ATPase - causing an inc in proton gradient - no ATP because pump is stopped
Prevent strands from reannealing
Two
Oligomycin
Nature and severity of phenotype vary from 1 individual to another - NF type 1

48. What does arsenic do and What are th results of poisoning
Ca/calmodulin in muscle to coordinate with muscle activity
Read from a fixed starting point as a continuous sequence of bases
2pq
Inhibits lipoic acid - vomiting - rice water stools - garlic breath

49. What other inflammatory process can induce a hemolytic anemia in NADPH defieicnt patients
IMP precursor
Hepatic glycogenolysis >> hepatic gluconeogenesis > adipose release of FFA
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
Infection - free radicals generated by inflammatory response

50. What is the activated carrier for aldehyddes
Rb and p53
TTP
Von gierkes - glucose 6 phosphatase
Glycine