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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. What happens with dry beriberi
Orotic acid phosphoribosyltransferase or orotidine 5'- phosphate decarboxylase
Mucus secreting globlet cells and antibody secreting plasma cells
Mutations at different loci can produce the same phenotype - marfans - MEN 2B - homocystinuria; all cause marfinoid habitus - also albinism
Polyneuritis - symmetrical muscle wasting

2. What tissues have only aldose reductase
Catalase positive (catalase neg produce H2O2 the cell can use) like S. aureus or aspergillus
Site of steroid synthesis and detoxification of drugs and poisons
Phenylalanine
Schwann cells - lens - retina - kidneys

3. What polar group does guanine have - and what non polar group does thymine have
Athralgias - fatigue - headaches - skin changes - sore throat - alopecia
Keep glutathione reduced so it can detoxify free radicals and peroxides
Cre - lox system
Ketone - methyl

4. What is the breakdown product of epi
Niacin - constituent of NAD and NADP - derived from tryptophan
Defect in fibrillin
Metanephrine
CO2 + NH4 needs carbamoyl phosphate synthase I - in the mitochondria

5. What is the RDE of the HMP shunt
Glucose 6 phosphate dehydrogenase (G6PD)
Pyruvate carboxylase - PEP carboxykinase - fructose 1 -6 biphosphatase - glucose 6 phosphatase
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
Specific glycosylases - AP endonuclease

6. Which direction does dynein go
Liver and leafy veggies
Fabrys - alpha galactosidase A - ceramide trihexoside - XR
Post to neg
Inc intestinal absorption fo calcium and phosphate - inc bone resorption

7. What is the rate determining enzyme (RDE) of glycolysis
Phosphofructokinase 1
Unwinds DNA template at replcation fork
Orotic acid phosphoribosyltransferase or orotidine 5'- phosphate decarboxylase
Sucrose = glucose + fructose - lactose = glucose + galactose

8. in a 100 meter sprint Where does energy come from
Tryptophan excretion in urine and dec absorption from the gut leading to pellagra
Genetic code is conserved throughout evolution - except for mito - archaebacteria - mycoplasma - and some yeast
Stored ATP - creatine phosphate - anaerobic glycolysis
Tyrosine

9. trinucleotide repeat fo myotonic dystrophy
Arg - lys - his - arg is most basic - has has no charge at body pH
Neurofibromatosis type 1 (von Recklinghausens disease)
CTG
Glucose 6 phosphate dehydrogenase (G6PD)

10. How does chloramphenicol work
Essential fructosuria - fructokinase AR
Heme synthesis - urea cycle and gluconeogenesis - HUGs take two
Inhibits 50S peptidyltransferase
Cystine kidney stones - cystine staghorn calculi - cystine is made of two cysteines connected by disulfide bond

11. Giving folate during early pregnancy is important to prevent what birth defects
Neural tube
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns
Plasma membrane - 3Na out - 2K in - ATP on cytoplasmic side
Type II

12. What is the trinucleotide repeat in fragile X
Anabolic processes like steroid and fatty acid synthesis - respiratory burst - P-450 - glutathione reductase
CGG
Phenytoin - MTX - and sulfonamides
Polyneuritis - symmetrical muscle wasting

13. How many rings do purines have
Limit protein diet - benzoate or phenylbutarate (both bind amino acids leading to excretion) can decrease ammonia levels
2 rings
Muscle
Malonyl coa (+ biotin= palmitiate - 1 16C fatty acid)

14. What other complex is similar to the pyruvate dehydrogenase complex in that it has the same co - factors and generates succinyl - CoA
Alpha - ketoglutarate dehydrogenase complex
Biotin
Inc orotic acid in urine - megaloblastic anemia (does not correct with B12 or folate) - failure to thrive
Neuralgia

15. What does degenerate/rundant genetic code refer to...
Directly inhibit the Na/K pump which leads to indirect inhibition of Na/Ca exchange - inc calcium inside the cell - inc cardiac contractility
Inherited lysosomal storage disorder; failure of addition of mannose 6 phosphate to lysosomal proteins - enzymes secreted outside of cell instead of lysosomes
More than 1 codon may code for the same amino acid
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

16. What substances are uncouling agents
Change resulting in early stop codon
2 -4 DNP - aspirin
CFTR gene - 7 - Phe 508
Elastase - inhibited by alpha1 antitrypsin

17. What causes biotin def
Antibiotic use or excessive ingestion of raw eggs
Dec methionine - inc cystiene - inc B12/folate
Heterochromatin = HighlyCondensed
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

18. What is a missense mutation
Lysine and arginine
Krabbes - galactocerebrosidase - galactocerebroside - AR
Changed AA (convservative - new AA is similar in chemical structure)
RNA

19. What happens in vit D excess
Microtubules
2 pyruvate - 2ATP - 2NADH - 2H+ - 2H2O
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
N- acteylcysteine - cleave disulfide bonds within mucus glycoproteins

20. What is a nonsense mutation
No mutation occuring at the locus - no selection for any genotypes at the locus - completely random mating - no migration
AR disorder characterized by defective neutral amino acid transporte on renal and intestinal epith cells
Change resulting in early stop codon
Tropoelastin with fibrillin scafolding

21. What is the structure of elastin
Inhibits RNA polymerase II - found in death cap mushrooms
Tropoelastin with fibrillin scafolding
Antioxidant - constituent of visual pigment - essential for nl differntiation of epithelial cells into specialized tissue (pancreatic cells - mucus secreting cells) used to treat measles
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible

22. What happens on the oxidative arm of the HMP shunt and What is the key enzyme
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Glucose 6P to CO2 - 2NADPH - ribulose 5P - G6PD - rate limiting step
5' to 3'
Liver - also in kidney and gut epithelium

23. What converts limit dextran to glucose
Mental retardation - hyperphagia - obesity - hypogonadism - hypotonia - deletion of normally active paternal allele on chromosome 15
GTP
Debranching enzyme
Polyneuritis - symmetrical muscle wasting

24. What is a silent mutation
Same AA - often base change in 3rd position of codon (tRNA wobble)
Oxidative is irreversible
AR
FISH

25. What are the characteristics of angelmans syndrome and How does it occur
Glycine - aspartate - glutamine
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Pyruvate to oxaloacetate (3C to 4C)
Mental retardation - seizures - ataxia - inappropriate laughter - deletion of normally active maternal allele

26. What enzyme converts glucose 1 p to UDP glucose
Vit K antagonist
Adds 2 carbon with the help of biotin
Night blindness - dry skin
UDP glucose pyrophosphorylase

27. what gene is implicated in fragile X syndrome - and What is the mutation
Basement membrane or basal lamina
FMR1 gene - methylation - associated with chromosomal breakage
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Dopamine beta hydroxylase

28. What bone disorder has x linked dominant inheritance
Sons of heterozygous mothers have 1/2 half chance of being affected - no male to male transmission - and often more severe in males - heterozygous females may be affected
Hypophophatemia rickets - vit D resistant ricketts - inc wasting of phosphate in proximal tubule - rickets like presentation
Metachromatic leukodystrophy - arylsulfatase A - cerebroside sulfate AR
Methionine encode by only 1 codon (AUG)

29. What step of uric acid synthesis does xanthine oxidase catalyze
Glucose 6 phosphatase
Hypoxanthine to xanthing and xanthine to uric acid
ATP - citrate
Depletes alpha - ketoglutarate leading to inhibition of TCA cycle - tremor slurring of speech - somnolence - vomiting - cerebral edema - blurring of vision

30. bilateral acoustic schwannomas - juvenile cataracts
Carbomoyl phosphate synthetase I
Lysine and leucine
Degradation of TG stored in adipocytes
NF2 on chromosome 22

31. Which antifungal drugs work on microtubules
Griseofulvin
Tuberous sclerosis
Glucose - 2Pi - 2ADP - 2NAD+
Peroxide

32. What is the amino acid precursor for GABA and glutathione
Glutamate
Pyrophosphate (B1 - thiamine - TPP) FAD (B2 - riboflavin) - NAD (B3 - niacin) - CoA (B5 pantothenate) - lipoic acid
SnRNPs
Elastase - inhibited by alpha1 antitrypsin

33. 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
PCR - denaturation - annealing - elongation
Transmitted only through mother - all offspring of affected females may show signs of disease
Alkaptonuria - may have debiliating arthralgias
Schwann cells - lens - retina - kidneys

34. Describe the replication fork
APRT + PRPP
Y shaped region along the DNA template where leading nad lagging strands are synthesized
Mental retardation - hyperphagia - obesity - hypogonadism - hypotonia - deletion of normally active paternal allele on chromosome 15
Poor defense from oxidizing agents - fava beans - sulfonamides - primaquine - antituberclosis drugs leadig to hemolytic anemia.

35. nucleotide repeat for fredreich's ataxia
VLDL
GAA
Connective tissue
MRNA

36. Gene imprinting implies that How many alleles are active at a single locus
One
Antioxidant - protects RBCs and membrances from free radical damage
Essential fructosuria - fructokinase AR
B100 and E

37. What is loss of heterozygosity and give an example
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
HDL
Cre - lox system
Thiamine - in thiamine pyrophosphate a cofactor for pyruvate dehydrogenase (glycolysis) - alpha ketoglutarate dehydrogenase (TCA cycle) - transketolase (HMP shunt) - and branched - chain AA dehydrogenase

38. What does universal genetic code refer to and What are some exception
Nonreciprocal chromosomal translocation that commonly involves chromosome pairs 13 - 14 - 15 - 21 - 22
Promotor - TATA box - and CAAT box - AT rich
Glycolysis - fatty acid synthesis - HMP shunt - protein synthesis (RER) - steroid synthesis (SER)
Genetic code is conserved throughout evolution - except for mito - archaebacteria - mycoplasma - and some yeast

39. What is the most common urea cycle disorder and What is the mode of inheritance?
PCR - denaturation - annealing - elongation
Ornithin transcarbamoylase def - x linked recesssive - other urea cycle enzymes defs are autosommal recessive
Proline and glycine (non glycosylated forms)
Kwashiorkor - small child with swollen belly

40. What is the activated carrier for electrons
Met - val - arg his
Meiotic nondisjunction of homologous chromosomes (associated with advanced maternal age) leading to trisomy 21
III - joint dislocation - anuerysms - organ rupture
NADH - NADPH - FADH2

41. What is the defectin IV - hypertriglyceridemia
Creat a nick in the helix to relieave supercoils created during replication
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns
Hepatic overproduction of VLDL causing pancreatitis - elvelated TGs and VLDL
1 kind with multiple subunits

42. fibrillin defect leading to connective tissue disorder affecting skeleton - heart - and eyes
Terminal regions - tropocollagen
Hereditary hemorrhagic telangiectasia (Osler - Weber - Rendu syndrome)
Marfans
Never go to G0 - divide rapidly with a short G1 - bone marrow - gut epi - skin - hair follicles

43. What does apoCII do
Malabsorption and steatorrhea (ADEK)
Cofactor for LPL
Inc melt - dec fluidity
Grows slowly - collapses quickly

44. Type IV collagen is an important structural componenet of the BM for which 3 organs
Not all individuals with a mutant genotype show the mutant phenotype
1 -25 OH2 D3 = calcitriol
ATP
Kidney - ears - eyes

45. What are the symptoms of vit A excess
Heterochromatin = HighlyCondensed
Athralgias - fatigue - headaches - skin changes - sore throat - alopecia
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
Medial dorsal nucleus of thalamus - mamillary bodies

46. recurrent pulmonary infxns in CF are due to what organisms
Pseudomonas and s aureus
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels
Mucus secreting globlet cells and antibody secreting plasma cells

47. What does a pyruvate dehydrogenase deficiency lead to and What are the findings
Medial dorsal nucleus of thalamus - mamillary bodies
Backup of substrate (pyruvate and alanine) resulting in lactic acidosis - congenital or acquired from thiamine def in EtOH - neuro defects
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver
Liver and leafy veggies

48. What is the purpose of the HMP shunt
3' end (with CCA)
Provide a source of NADPH from an abundantly available glucose 6P - create ribose for nucleotide synthesis and glycolytic intermediates
Glycogen and FFA oxidation; glucose conserved for final sprinting
Acetyl - CoA carboxylase (ACC)

49. developmental delay - gargoylism - airway obstruction - corneal clouding - hepatosplenomegaly
ATP
Stored ATP - creatine phosphate - anaerobic glycolysis
Poly A polymerase - signal is AAUAA
Hurlers syndrome - alpha L iduronidase - heparan sulfate/dermatan sulfate - AR

50. cytoskeletal elements in micorvilli - muscle contracting fibers - cytokenesis - adherens jxns
40 - 60 - 80
Glucose to G-6P - hexokinase and fructose -6P to fructose 1 -6 BP phosphofructokinase -1
Actin and myosin
Stored and undergoes glycogenolysis to maintain blood sugar at appropriate levels