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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 is the defect in fructose intolerance and What does it cause
Depleted for gluconeogenesis staling the TCA cycle and shunting glucose and FFA to production of ketone bodies
Alkaptonuria - may have debiliating arthralgias
Aldolase B - AR - fructose 1P accumulates causing a dec in availabel phosphate which inhibts glycogenolysis and gluconeogenesis leading to hypoglycemia - cirrhosis - jaundice and vomiting
Actin and myosin

2. How are the many staggered tropocollagen molecules reinforced
Mebendazole/thiabendazole
Degredation of TG circulating in chylomicrons and VLDLs
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
Covalent cross - linking by lysyl oxidase to make collagen fibrils

3. depression - progressive dementia - choreiform movements - caudate atrophy and dec levels of GABA and ACH in the brain
Huntingtons
Methionine encode by only 1 codon (AUG)
Tryptophan
CO2 + NH4 needs carbamoyl phosphate synthase I - in the mitochondria

4. Where does gluconeogenesis primarily happen and What are other sites where the enzymes are located
Liver - also in kidney and gut epithelium
Hypoglycemia
High output cardiac failure - dilated cardiomyopathy - edema
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty

5. What does a mischarge tRNA do
For proteins and lipids from ER to plasma membrane - lysosomes and secretory vesicles
Reads usual codon but inserts wrong AA
Antibiotic use or excessive ingestion of raw eggs
Phenylalanine hydroxylase

6. What are the complications/signs of familial hypercholesterolemia
Ca/calmodulin in muscle to coordinate with muscle activity
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver
Ribose 5- P to PRPP
Sever atherosclerotic disease early in life - and tendon xanthomas on the achilles - MI may develop before 20

7. phosphorylation of glucose to yield glucose 6 phosphate serves as the 1st step of what rxns and what enzymes catalyze it
BOne
ADEK - dependent on gut (ileum) and pancreas - accumulate in fat and can cause toxicity
They yield only acetyl - CoA equivalents
Glycolysis and the glycogen synthesis in the liver - hexokinase or glucokinase

8. What is codominance and give an example
Tropoelastin with fibrillin scafolding
Mental retardation - hyperphagia - obesity - hypogonadism - hypotonia - deletion of normally active paternal allele on chromosome 15
Neither of 2 alleles is dominant - blood groups
Polycystic liver disease - berry aneurysm - mitral valve prolapse

9. What step of uric acid synthesis does xanthine oxidase catalyze
Schilling test
Hypoxanthine to xanthing and xanthine to uric acid
In ER - glucose 6- P to glucose
Nonreciprocal chromosomal translocation that commonly involves chromosome pairs 13 - 14 - 15 - 21 - 22

10. caf
Scrutinizes - hydrolyzes the bond
Neurofibromatosis type 1 (von Recklinghausens disease)
HDL
Nucleotide excision repair - xeroderma pigmentosum; unable to repair thymidine dimers caused by UV light

11. What liberates glucose from glucose 6 P
ATP and alanine
Zero
Phenylalanine hydroxylase
Glucose 6 phosphatase

12. what gene is implicated in fragile X syndrome - and What is the mutation
Animal products - synthesized only by microorganisms - large reserve pool - mainly in liver
Miscarriage - stillbirth - chromosomal imbalance (down - patau)
FMR1 gene - methylation - associated with chromosomal breakage
X- linked recessive

13. What is the order of severity for the different types of mutations
Propionyl - CoA to methylmalonyl - CoA (3C to 4C)
Provide a source of NADPH from an abundantly available glucose 6P - create ribose for nucleotide synthesis and glycolytic intermediates
Converted to THF - a coenzyme for one - carbon transfer/methylation reactions - important for synthesis of nitrogenous bases in DNA and RNA
Nonsense > missense > silent

14. What is NADPH's role inside RBCs
Dopamine beta hydroxylase
Keep glutathione reduced so it can detoxify free radicals and peroxides
2 rings
Protein kinase A

15. What do albinism - ARPKD - CF - glycogen storage diseases - hemochromatosis - mucopolysaccharidoses (except Hunters) PKU - sickle cell - sphingolipodoses (except Fabrys) thalassemias have in common
Oxidative and nonoxidative - no ATP produced or used
By inhibiting formation of the initiation complex and cause misreading of mRNA
Autosomal recessive diseases
Prokaryotic only - degrades RNA primer and fills in the gap with DNA

16. What is the amino acid precursor for catecholamines
Phenylalanine
ATP
Inability to transport LCFAs into mitochondria results in toxic accumulation causing weakness - hypotonia - hyperketotic hyperglycemia
1- capping on 5' (7- methyguanosine) 2 - polyadenylation on 3' end 3 - splicing out of introns

17. What sugar is sorbitol converted to and via what enzyme - and What can happen in cells lacking this enzyme
Actin and myosin
Inability to transport LCFAs into mitochondria results in toxic accumulation causing weakness - hypotonia - hyperketotic hyperglycemia
Regulatory proteins that control cell cycle events; phase specific; activate CDKs
Fructose via sorbitol dehydrogenase - inc sorbitol leading to osmotic damage as in cataracts - retinopathy - peripheral neuropathy as in diabetes

18. What is a missense mutation
Same AA - often base change in 3rd position of codon (tRNA wobble)
NADH - NADPH - FADH2
Changed AA (convservative - new AA is similar in chemical structure)
Myeloperoxidase

19. What substance inside the cell reduces glutatione
B48 - AIV - CII - E
Paclitaxel
NADPH
Alanine

20. trinucleotide repeat fo myotonic dystrophy
Same AA - often base change in 3rd position of codon (tRNA wobble)
CTG
Skin
Hydroxyurea - inhibits ribonucleotide reductase - 6 MP - blocks de novo purine synthesis - 5 FU inhibits thymidilate synthase - MTX - inhibits DHFR - Trimethroprin inhibits bacterial DHFR

21. What is the main source of folate
Retardation - self mutilation - aggression - hyperuricemia - gout - choreoathetosis
Malonyl coa (+ biotin= palmitiate - 1 16C fatty acid)
Lysine and arginine
Foliage - small reserve in liver - eat green leaves

22. Describe the location and fxn of the Na/K ATPase
CGG
Plasma membrane - 3Na out - 2K in - ATP on cytoplasmic side
Protein kinase A
Cartilage - hyaline - vitreous body - nucleus pulposus

23. Which step in the de novo purine and pyrimidine synthesis pathway requires aspartate - glycine - glutamine and THF
Leu - lys
Depleted for gluconeogenesis staling the TCA cycle and shunting glucose and FFA to production of ketone bodies
Deamination
Ribose 5- P to PRPP

24. What is trimming
Mental retardation - macro - orchidism - long face with large jaw - large everted ears - autism - and mitral valve prolapse
Wernicke - korsakoff - dry and wet beriberi
Removal of N or C termal propeptides from zymogens to generate mature proteins
Binds to LDL receptor - mediates VLDL secretion

25. What lab value can distinguish orotic aciduria from ornithine transcarbamoylase def?
Transfers methyl units
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
OTC has hyperammonemia - orotic aciduira does not
Lack of proper dietary therapy during pregnancy leading to microcephaly - mental retardation growth retardation - congenital heart defects

26. What are the purely ketogenic amino acids
Converted to THF - a coenzyme for one - carbon transfer/methylation reactions - important for synthesis of nitrogenous bases in DNA and RNA
Glucose - 2Pi - 2ADP - 2NAD+
Leu - lys
Cre - lox system

27. What is the RDE of cholesterol synthesis
Mental retardation - flat facies - prominent epicanthal folds - simian crease - gap between 1st 2 toes - duodenal atresia - congenital heart disease (ASD) - inc risk of All and Alzheimers
Tryosine hydroxylase
Each codon specifies only 1 amino acid
HMG- CoA reductase

28. What kind of branches do glycogen branches have
Alpha 1 -6 and alpha 1 -4
Initiate chains
Flank pain - hematuria - HTN - progressive renal failure
In ER - glucose 6- P to glucose

29. In what cell is collagen synthesis initiated
African Americans and Asians
Fibroblast
Orotic acid to UMP
Inhibit DNA gyrase specific for prokaryotic topoisomerase

30. Of the four possible fates for pyruvate - which one is a transition from glycolysis to TCA cycle
Aberrant 3rd and 4th branchial arches causing 22q11 deletion - cleft palate - abnl facies - thymic dysplasia - cardiac defects - hypocalcemia secondary to parathyroid aplasia
Via 1 proprionyl - CoA which can enter the TCA as succinyl - CoA and undergo gluconeogenesis
Antigen - antibody reactivity - can look for antigen or antibody in patients blood
Acetyl - CoA

31. What does NADPH oxidase deficiency result in and why
Chronic granulomatous disease - no respiatory burst - no formatino of ROS
Exerts a dominant effect - a heterozygote produces a nonfxnal altered protein that also prevents the normal gene from functioning - mutation of Tx factor its allosteric site - nonfxning mutant can still bind DNA - preventing wild type Tx from binding
ATP
Alcohol version of glucose - can trap glucose in cell - aldose reductase

32. What inhibits the carnitine shuttle
Catabolic processes to carry reducing equivalents away as NADH
Malonyl coa
Microtuble polymerization defect causing a dec in phagocytosis results in recurrent pyogenic infections - partial albinism - and peripheral neuropathy
Never go to G0 - divide rapidly with a short G1 - bone marrow - gut epi - skin - hair follicles

33. How does OTC def present
Zero
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
Polycystic liver disease - berry aneurysm - mitral valve prolapse
Marasmus - muscle wasting

34. What two pathways is carbomoyl phosphate involved in - and what enzyme deficiency leads to a build of carbamoyl phosphate leading to what element in pyrimidine synthesis
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
Night blindness - dry skin
OTC has hyperammonemia - orotic aciduira does not
FAP

35. trinucleotide repeat for huntingtons
CAG
Macrocytic - megaloblastic anemia - hypersegmented PMNs - neurologic symptoms - (parasthesias - subacute combined degeneration) due to abnl myelin - prolonged becomes irreversible
Lack of tyrosinase (no melanin) AR ordefective tyrosine transporters (less tyrosine) - can results in lack of migration of NC cells
Receptor tyrosine kinases - protein phosphatase - takes phosphate off glycogen phosphorylase kinase inactivating it

36. What enzyme degrades a small amount of glycogen in lysosomes
Alpha 1 -4 glucosidase
Galactitol - galactose appears in blood and urine - can cause infantile cataracta - AR
1 -25 OH2 D3 = calcitriol
Consesus sequenec of base pairs

37. What are the irreversible enzymes of gluconeogenesis
Isocitrate dehydrogenase
II - VII - IX - X (1972) protein C and S
Pyruvate carboxylase - PEP carboxykinase - fructose 1 -6 biphosphatase - glucose 6 phosphatase
Excess ATP - dATP - feeback inhibits ribonucleotide reductase - no DNA synthesis

38. What is the function of biotin
Phenylalanine hydroxylase
Cofactor of carboxyltion enzymes: pyruvate carboxylase - acetate - CoA carboxylase - and propionyl - CoA carboxylase
MRNA - tRNA
Reads usual codon but inserts wrong AA

39. In which state is FBPase -2 active
Octamer = 2 sets of H2A - H2B - H3 - H4 - tie =H1
Fasting
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
Elastase - inhibited by alpha1 antitrypsin

40. What does a phosphatase do
Hypercalciuria - loss of appetite - stupor - seen in sarcoidosis from activation fo vit D by epithelioid macrophage
Removes phosphate group from substrate
Flank pain - hematuria - HTN - progressive renal failure
Cytosol

41. What does apoB100 do
Binds to LDL receptor - mediates VLDL secretion
ADEK - dependent on gut (ileum) and pancreas - accumulate in fat and can cause toxicity
Chylomicrons
UGA - UAA and UAG

42. Why is albinism inheritnace varialbe due to...
Binds to LDL receptor - mediates VLDL secretion
NADPH
Locus heterogeneity - ocular albinism is x- linked recessive
VLDL

43. Mediates reverse cholesterol transport from periphery to liver - acts as respository for apoC an apoE - secreted from both liver and small intestine
Glucose - 2Pi - 2ADP - 2NAD+
HDL
Williams syndrome
Two

44. hepatosplenomegaly - aseptic necrosis of femur - bone crisis - MACS that look like crumpled tissue paper

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45. 1 g of protein or cabrohydrate = ?kcal
III - joint dislocation - anuerysms - organ rupture
X linked frame shif mutation
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
Four

46. How is Lesch Neyhan inherited
X- linked recessive
Pyrophosphate (B1 - thiamine - TPP) FAD (B2 - riboflavin) - NAD (B3 - niacin) - CoA (B5 pantothenate) - lipoic acid
Homocystein in ruine - mental retardation - osteoporosis - tall stature - kyphosis - lens subluxation and atherosclerosis leading to stroke and MI - cysteine
Wernicke - korsakoff - dry and wet beriberi

47. cardiomegaly - systemic findings leading to early death - dz and enzyme

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48. What does the vimentin stain for
Stored ATP - creatine phosphate - anaerobic glycolysis
Alcohol version of glucose - can trap glucose in cell - aldose reductase
Griseofulvin
Connective tissue

49. recurrent pulmonary infxns in CF are due to what organisms
Pseudomonas and s aureus
Inc intestinal absorption fo calcium and phosphate - inc bone resorption
Uses ATP to add high energy phophate group onto substrate
Carbomoyl phosphate synthetase I

50. Fluorescent DNA or RNA probe binds to specific gene of interest - used for specific localization of genes and direct visualization of anomalies - like microdeletions - at molecular level
Palate - facial and cardiac defects
Glycine - aspartate - glutamine
Zero
FISH