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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. nucleotide repeat for fragile x
CGG
Neither of 2 alleles is dominant - blood groups
Skin
Metanephrine

2. What does fomepizole do
In ER - glucose 6- P to glucose
CarTWOlage
Acetyl - CoA carboxylase (ACC)
Inhibits EtOH dehydrogenase and is an antidote for methanol and ethylene glycol poisoning

3. What is heteroplasmy
Microtuble polymerization defect causing a dec in phagocytosis results in recurrent pyogenic infections - partial albinism - and peripheral neuropathy
Heterochromatin = HighlyCondensed
Hepatic glycogenolysis >> hepatic gluconeogenesis > adipose release of FFA
Presence of both nl and mutated mtDNA resulting in mitochondrial inherited disease

4. What does DNA poly III do?

5. What bone disorder has x linked dominant inheritance
Offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent
Glucose to G-6P - hexokinase and fructose -6P to fructose 1 -6 BP phosphofructokinase -1
Absence of galactose 1 phosphate uridyltransferase - accumulation of toxic substances leads to failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation
Hypophophatemia rickets - vit D resistant ricketts - inc wasting of phosphate in proximal tubule - rickets like presentation

6. How many nucTIDEs is a tRNA and What does the secondary sturcture form
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)
75 to 90 - cloverleaf
Pseudomonas and s aureus
Aberrant 3rd and 4th branchial arches causing 22q11 deletion - cleft palate - abnl facies - thymic dysplasia - cardiac defects - hypocalcemia secondary to parathyroid aplasia

7. decreases In what substances can cause PKU
Cri du chat
Phosphenolpyruvate to pyruvate catalyzed by pyruvate kinase
Phenylalanine hydroxylase - tetrahydrobiopterin cofactor
Hepatic glycogenolysis >> hepatic gluconeogenesis > adipose release of FFA

8. What does high cholesterol or long saturated fatty acid content do to the melting temperature and fluidity
Inc melt - dec fluidity
Carbomoyl phosphate synthetase I
Silencers
Rickets in kids - bending bones - osteomalacia in adults - hypocalcemia tetany - breast milk has dec vit D (supplement in dark skinned patients)

9. What does a dehydrogenase do
Hurlers syndrome - alpha L iduronidase - heparan sulfate/dermatan sulfate - AR
Oxidizes substrate
Lysine and arginine
Cyclin dependent kinases;constitutive and inactive

10. Type II collagen
1 gene had >1 effect on an individuals phenotype - PKU causes many seemingly unrelated symptoms ranging from mental retardation to hair/skin changes
Thymic - parathyroid and cardiac
Cartilage - hyaline - vitreous body - nucleus pulposus
Prevent strands from reannealing

11. developmental delay - gargoylism - airway obstruction - corneal clouding - hepatosplenomegaly
Hurlers syndrome - alpha L iduronidase - heparan sulfate/dermatan sulfate - AR
Isocitrate dehydrogenase
Never go to G0 - divide rapidly with a short G1 - bone marrow - gut epi - skin - hair follicles
1 -25 OH2 D3 = calcitriol

12. Type IV BM
Dec phenylalanine (contained in aspartame - Nutrasweet) inc tyrosine in diet
APKD1 on chromosome 16
Mental retardation - macro - orchidism - long face with large jaw - large everted ears - autism - and mitral valve prolapse
4 under the floor

13. What are the function of vit C
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
30 - glycerol -3- phosphate shuttle
HMG- CoA synthase
Malabsorption (sprue - enteritis) lack of intrinsic factor from pernicious anemia - gastric bypass surgery or absence of terminal ileum as in Crohns

14. What does Adenosine deaminase deficiency cause a build up of - and What does that lead to?
Ubiquitous - low Km - high affinity - low capacity low Vmax - uninduced by insulin
Avidin
NADH - NADPH - FADH2
Excess ATP - dATP - feeback inhibits ribonucleotide reductase - no DNA synthesis

15. What is the RDE of the HMP shunt
ATPase that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets
Glucose 6 phosphate dehydrogenase (G6PD)
IMP precursor
Wrinkles and acne

16. What is the pathway in the fed state leading to dec FBPase -2 and inc PFK-2
One
Absence of galactose 1 phosphate uridyltransferase - accumulation of toxic substances leads to failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation
Facial flushing
Inc insulin - dec cAMP - dec PKA

17. What is the RER called in neurons and What is made there
Homocystein in ruine - mental retardation - osteoporosis - tall stature - kyphosis - lens subluxation and atherosclerosis leading to stroke and MI - cysteine
Glycogen phosphorylase
Nissl body - enzyme and NTs
Neuralgia

18. progressive neurodegeneration - developmental delay - cherry red spot on macula - lysosomes with onion skin - NO hepatosplenomegaly
FAP
Coenzyme A - lipoamide
Carbomoyl phosphate synthetase II
Tay- Sachs - hexosaminidase A - GM2 ganglioside - AR

19. What is made fir rNucleotides or deoxyrNucleotides and what enzyme is necessary to convert one to the next
Disease
Hereditary defect of renal tubular amino acid transporter for cystein - ornithine - lysine and arginine in PCT
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
Ribos first then deoxyribos with ribonucleotide reductase

20. Adenosine deaminase deficiency is an important cause of what immunodeficiency?
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Gaucher's - beta glucocerebrosidase - glucocerebrosie - AR
Dec DNA - dec lymphos leads to SCID
B6

21. If two alleles are present - but the active allele is deleted - what happens
Phosphorylation - glycosylation - hydroxylation
Mediates chylomicron secretion
AD absent of dec LDL receptors causes accelerated atherosclerosis - achilles xanthomas and corneal arcus - increase LDL and elecated cholesterol
Disease

22. What substance accumulates in galactokinase def and What is the clinical picture
Phenylalanine hydroxylase - tetrahydrobiopterin cofactor
Arg - lys - his - arg is most basic - has has no charge at body pH
Galactitol - galactose appears in blood and urine - can cause infantile cataracta - AR
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

23. Where are FADH2 electrons transferred to...
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible
Comlex II
Accelearted muscle breakdown
HMP shunt

24. What is the trinucleotide repeat in fragile X
CGG
Change resulting in misreading of all nucleotides downstream - usually resulting in a truncated nonfxnal protein
Sever atherosclerotic disease early in life - and tendon xanthomas on the achilles - MI may develop before 20
Histidine

25. cytoskeletal elements in micorvilli - muscle contracting fibers - cytokenesis - adherens jxns
Actin and myosin
Read from a fixed starting point as a continuous sequence of bases
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
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver

26. bilateral - massive enlargement of of kidneys due to multiple large cysts
Facial flushing
ADPKD
Fructose via sorbitol dehydrogenase - inc sorbitol leading to osmotic damage as in cataracts - retinopathy - peripheral neuropathy as in diabetes
Site of steroid synthesis and detoxification of drugs and poisons

27. What does a southern blot use as its sample
Neurons
Changed AA (convservative - new AA is similar in chemical structure)
Antioxidant - protects RBCs and membrances from free radical damage
DNA

28. How do labile celss grow and regenerate and What are examples
Never go to G0 - divide rapidly with a short G1 - bone marrow - gut epi - skin - hair follicles
Nonsense > missense > silent
Antibiotic use or excessive ingestion of raw eggs
Glucose to G-6P - hexokinase and fructose -6P to fructose 1 -6 BP phosphofructokinase -1

29. Name as many x- linked recessive disorders as you can

30. In addition to fructose and galactose - what sugards should be excluded from the diets of patients with disorders of fructose or galactose metabolism
Immotile cilia due to dynein arm defect - male and femail infertile - bronchiectasis - recurrent sinusitis - associated with situs inversus
Sucrose = glucose + fructose - lactose = glucose + galactose
HMP shunt
Citrate - isocitrate - alpha ketoglutarate - succinyl - CoA - succinate - fumarate - malate - oxaleoacetate

31. What is loss of heterozygosity and give an example
TRNA
1 ring
Autosomal recessive diseases
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

32. What does apoE do
Infection - free radicals generated by inflammatory response
Mediates extra remnant take up
Anchor muscle fibers - primarily in skeletal and cardiac muscle
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light

33. What is the amino acid precursor for porphyrin and heme
Acetyl - CoA to malonyl - CoA (2C to 3C)
Tryptophan
Dermatitis - glossitis - and diarrhea
Glycine

34. What can vit B3 be used to treat
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
Liver - ovaries - seminal vesicles
Hyperlipidemia
B(1 - 2 - 3 - 5 - 6 - 12) C - biotin and folate (B12 and folate are stored)

35. What 3 steps in RNA processing occur after transcription

36. What is the RDE of fatty acid oxidation
X linked frame shif mutation
HMP shunt
Carnitine acyltransferase I
NADH - NADPH - FADH2

37. What enzyme converts adenine to AMP
F16BP
Cartilage - hyaline - vitreous body - nucleus pulposus
APRT + PRPP
Schilling test

38. What happens in the first stage of collagen synthesis - and Where does it happen
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)
Citrate - isocitrate - alpha ketoglutarate - succinyl - CoA - succinate - fumarate - malate - oxaleoacetate
Confusion - opthalmoplegia - ataxia - confabulation - personality changes and memory loss
Mental retardation - hyperphagia - obesity - hypogonadism - hypotonia - deletion of normally active paternal allele on chromosome 15

39. What is a silent mutation
Uses ATP to add high energy phophate group onto substrate
N to C
Same AA - often base change in 3rd position of codon (tRNA wobble)
Inc dicarboxylic acids - dec in glucose and ketones

40. What is maternal PKU
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns
Lack of proper dietary therapy during pregnancy leading to microcephaly - mental retardation growth retardation - congenital heart defects
Absence of galactose 1 phosphate uridyltransferase - accumulation of toxic substances leads to failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation
Read from a fixed starting point as a continuous sequence of bases

41. 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
Scrutinizes - hydrolyzes the bond
Cyclin dependent kinases;constitutive and inactive
Metachromatic leukodystrophy - arylsulfatase A - cerebroside sulfate AR
Mebendazole/thiabendazole

42. What produces NADPH
HMP shunt
CAG
Arg and his inc in histones Which bind negatively charged DNA
Convulsions - hyperirritability - peripheral neuropathy - deficiency inducible by INH and oral contraceptives - sideroblastic anemais

43. What do neurofilaments stain for
Loss of brush border enzyme causing bloating - cramps - osmotic diarrhea
Neurons
Athralgias - fatigue - headaches - skin changes - sore throat - alopecia
Glucose to G-6P - hexokinase and fructose -6P to fructose 1 -6 BP phosphofructokinase -1

44. What does a phosphatase do
Inc vit B6
Impaired glucose breakdown leading to ATP depletion; highly affected aerobic tissues like brain and heart affected first
Fabrys - alpha galactosidase A - ceramide trihexoside - XR
Removes phosphate group from substrate

45. What does vit E def cause
Euchromatin
Inc fragility of RBC - hemolytic anemia - muscle weakness - posterior column and spinocerebellar tract demyelination
Intermediate filaments
PFK - rate limiting enzyme

46. What is disulfiram used for
Metachromatic leukodystrophy - arylsulfatase A - cerebroside sulfate AR
Neither of 2 alleles is dominant - blood groups
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
Inhibits acetaldehyde dehydrogenase and contributes to hangover symptoms

47. Broadly - What can cause fat - soluble vitamin deficiencies
Liver - ovaries - seminal vesicles
Malapsorption syndromes like sprue or CF or mineral oil intake
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Connective tissue

48. What is the RDE of glycogenolysis
Occurs when cells in the body have different genetic makeup - can be germline mosaic - which may produce a disease that is not carried by parents somatic cells - lyonization - random X inactivation in females
Glycogen phosphorylase
Glycogen synthase
Dopamine beta hydroxylase

49. What step begins the urea cycle and What is the enzyme needed - Where does it happen
CO2 + NH4 needs carbamoyl phosphate synthase I - in the mitochondria
Familial hypercholesterolemia - hyperlipidemia type IIA
Via 1 proprionyl - CoA which can enter the TCA as succinyl - CoA and undergo gluconeogenesis
Metachromatic leukodystrophy - arylsulfatase A - cerebroside sulfate AR

50. What does Alports syndrome cause and why
Alcohol version of glucose - can trap glucose in cell - aldose reductase
Progressive hreditary nephritis and deafness - associated with occular disturbances - due to abnl type IV collagen - usually x- linked recessive
Essential fructosuria - fructokinase AR
Mutated dystrophin gene - less severe - adolescence