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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 do DNA topoisomerases do
Change resulting in misreading of all nucleotides downstream - usually resulting in a truncated nonfxnal protein
Fasting
Removal of N or C termal propeptides from zymogens to generate mature proteins
Creat a nick in the helix to relieave supercoils created during replication

2. What residues are hydroxylated in step 2 of collagen synthesis - and What does this require
N to C
Proline and lysine - vit C
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
Base + ribose + phosphate (3' -5') phosphodiester bond

3. The golgi apparatus fxns as a distribution center between what organelles in the cell and What does it process
Removal of N or C termal propeptides from zymogens to generate mature proteins
For proteins and lipids from ER to plasma membrane - lysosomes and secretory vesicles
Core proteins
Proline and glycine (non glycosylated forms)

4. What does Alports syndrome cause and why
Tuberous sclerosis
Nature and severity of phenotype vary from 1 individual to another - NF type 1
Progressive hreditary nephritis and deafness - associated with occular disturbances - due to abnl type IV collagen - usually x- linked recessive
Sever atherosclerotic disease early in life - and tendon xanthomas on the achilles - MI may develop before 20

5. What is the amino acid precuros for niacin and serotonin/melatonin
G6PD
APKD1 on chromosome 16
Karyotyping
Tryptophan

6. Very Poor Carbohydrate Metabolism stands for 4 of the glycogen storage diseases - What are thy

7. Which cells are rich in smooth ER
Glycine
Liver hepatocytes and steroid producing cells of the adrenal cortex
Never go to G0 - divide rapidly with a short G1 - bone marrow - gut epi - skin - hair follicles
B6

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

9. facial lesions - hypopigmented 'ash leaf spots -' cortical and retinal hamartomas - seizures - mental retardation - renal cysts - renal angiomyolipomas - cardiac rhabdomyomas - inc risk of astrocytomas
Cystine kidney stones - cystine staghorn calculi - cystine is made of two cysteines connected by disulfide bond
30 - glycerol -3- phosphate shuttle
Tuberous sclerosis
Muscle

10. 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
Neimann - pick - sphingomyelinase - sphingomyelin - AR
Via 1 proprionyl - CoA which can enter the TCA as succinyl - CoA and undergo gluconeogenesis
CTG

11. In mismatch repair - which strand is recognized and In what hereditary syndrome is this defective
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
Connective tissue
Orotic acid phosphoribosyltransferase or orotidine 5'- phosphate decarboxylase
Unmethylated - newly synthesized - HNPCC

12. What does biotin def cause
Familial hypercholesterolemia - hyperlipidemia type IIA
Inhibits RNA polymerase II - found in death cap mushrooms
Dermatitis - alopecia - enteritis
Production of a recombinant DNA molecule that is self perpetuating - plasmids - selection - restriction enzyme cleavage - tissue mRNA with reverse transcriptase to make cDNA

13. Outside the fibroblast What part of procollagen is cleaved and What is it transformed into
Terminal regions - tropocollagen
Oral uridine administration
Silencers
Acetyl - CoA carboxylase (ACC)

14. If two alleles are present - but the active allele is deleted - what happens
1 ring
Disease
Glucose -6 phosphate
Impaired glucose breakdown leading to ATP depletion; highly affected aerobic tissues like brain and heart affected first

15. When are glycogen reserves depleted
Changed AA (convservative - new AA is similar in chemical structure)
Stored ATP - creatine phosphate - anaerobic glycolysis
After day 1
Exons

16. What are the blood glucose levels maintained by for days 1-3
Exons
Malabsorption (sprue - enteritis) lack of intrinsic factor from pernicious anemia - gastric bypass surgery or absence of terminal ileum as in Crohns
Keep glutathione reduced so it can detoxify free radicals and peroxides
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)

17. ADPKD is associated with What additional conditions
Alkaptonuria - may have debiliating arthralgias
Defect in fibrillin
Adds an inorganic phosphate onto substrate without using ATP
Polycystic liver disease - berry aneurysm - mitral valve prolapse

18. What does degenerate/rundant genetic code refer to...
Carnitine shuttle - acyl - coa from cyto to mito
More than 1 codon may code for the same amino acid
Chylomicrons
They yield only acetyl - CoA equivalents

19. What does a carboxylase do
Phenylalanine hydroxylase - tetrahydrobiopterin cofactor
Adds 2 carbon with the help of biotin
Aldolase B - AR - fructose 1P accumulates causing a dec in availabel phosphate which inhibts glycogenolysis and gluconeogenesis leading to hypoglycemia - cirrhosis - jaundice and vomiting
Transfers methyl units

20. Of the four possible fates for pyruvate - which ends anaerobic glycolysis as in RBCs - leukocytes - kidney medulla - lens - testes and cornea
Lactate
Progressive hreditary nephritis and deafness - associated with occular disturbances - due to abnl type IV collagen - usually x- linked recessive
Malapsorption syndromes like sprue or CF or mineral oil intake
Antibiotic use or excessive ingestion of raw eggs

21. What is loss of heterozygosity and give an example
HMP shunt
Acetyl - CoA to malonyl - CoA (2C to 3C)
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
Propionyl - CoA to methylmalonyl - CoA (3C to 4C)

22. What causes Down syndrome
Many generations - both male and female affected - often pleiotropic - can present clinically after puberty
Hydroxyurea - inhibits ribonucleotide reductase - 6 MP - blocks de novo purine synthesis - 5 FU inhibits thymidilate synthase - MTX - inhibits DHFR - Trimethroprin inhibits bacterial DHFR
High output cardiac failure - dilated cardiomyopathy - edema
Meiotic nondisjunction of homologous chromosomes (associated with advanced maternal age) leading to trisomy 21

23. How does patients present with ADPKD
Debranching enzyme
Fibrofatty replacement of muscle - cardiac myopathy
Flank pain - hematuria - HTN - progressive renal failure
Inability to transport LCFAs into mitochondria results in toxic accumulation causing weakness - hypotonia - hyperketotic hyperglycemia

24. What happens do glycogen in skeletal muscle during exercise
Debranching enzyme
Glycogenolysis to form glucose
ATP
Disorder of aromatic amino acid metabolism

25. What is the hardy weinberg allele prevalence
Exons
Microtuble polymerization defect causing a dec in phagocytosis results in recurrent pyogenic infections - partial albinism - and peripheral neuropathy
P+q = 1
LCAT (lecithin cholesterol acyltransferase)

26. What converts DOPA to dopamine
Glucose - 2Pi - 2ADP - 2NAD+
Dopa decarboxylase
Neg to pos
Offspring receives 2 copies of a chromosome from 1 parent and no copies from the other parent

27. What does a mischarge tRNA do
Stop codon is recognized by release factor - and completed protein is released from ribosome
Protein
Lacks glucose 6 phophatase
Reads usual codon but inserts wrong AA

28. What amino acid makes up most of the octamer
Activates LCAT
Lysine and arginine
Glucose - 2Pi - 2ADP - 2NAD+
ATP and methionine

29. What are the 3 AR forms of homocystinuria
Cystathionine synthase def - dec affinity of cystathionine synthase for pyridoxal phosphate - homocystein methyltransferase def
Night blindness - dry skin
Connective tissue
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

30. What happens in the first stage of collagen synthesis - and Where does it happen
FAP
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
RER - translation of alpha chains - usually Gly-X-Y polypeptide (preprocollagen)
Glycolysis and the glycogen synthesis in the liver - hexokinase or glucokinase

31. pyruvate carboxylase catalyzes what rxn
Pyruvate to oxaloacetate (3C to 4C)
Aberrant 3rd and 4th branchial arches causing 22q11 deletion - cleft palate - abnl facies - thymic dysplasia - cardiac defects - hypocalcemia secondary to parathyroid aplasia
Intermediate filaments
CarTWOlage

32. What does a northern blot use as its sample
Glycogen phosphorylase
RNA
Y shaped region along the DNA template where leading nad lagging strands are synthesized
9+2 arrangement of microtubules

33. What do neurofilaments stain for
Robertsonian translocation and mosaicism
1 -25 OH2 D3 = calcitriol
Neurons
Tryptophan excretion in urine and dec absorption from the gut leading to pellagra

34. What does vit C def cause
FAP
CAG
Scurvy - swollen gums - bruising - hemarthrosis - anemia - poor wound healing - weakened immune response
3' end (with CCA)

35. What tissues have only aldose reductase
Schwann cells - lens - retina - kidneys
HMG- CoA - brain to 2 molecules of acetyl - Coa - excreted in urine
ATP and methionine
Marasmus - muscle wasting

36. What is the function and name of vit B6
32 - malate aspartate shuttle
Nonreciprocal chromosomal translocation that commonly involves chromosome pairs 13 - 14 - 15 - 21 - 22
Inc Cl - in sweat
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

37. What are the glucogenic essential amino acids
Huntingtons
Cleft palate - cardiac abnl - pregs test
Met - val - arg his
One

38. What enzyme converts phenylalanine to tyrosin
Adenylyl cycle - inc cAMP - inc PKA - glycogen phosphorylase kinase activated - glycogen phosphoylase active - glycolysis
Phenylalanine hydroxylase
Macrocytic - megaloblastic anemia - no neurologic sx - most common vit def in the US - seen in EtOH and pregs
Lack of tyrosinase (no melanin) AR ordefective tyrosine transporters (less tyrosine) - can results in lack of migration of NC cells

39. What does hormone sensitive lipase do
Lactate
Degradation of TG stored in adipocytes
Mental retardation - seizures - ataxia - inappropriate laughter - deletion of normally active maternal allele
B12 and folate

40. What is DNA cloning and How do you do it?
HDL
Production of a recombinant DNA molecule that is self perpetuating - plasmids - selection - restriction enzyme cleavage - tissue mRNA with reverse transcriptase to make cDNA
Failure to track objects or develop a social smile
IDL

41. What tissue samples are used for karyotyping
Blood - bone marrown - amniotic fluid - placental tissue
Heme synthesis - urea cycle and gluconeogenesis - HUGs take two
High output cardiac failure - dilated cardiomyopathy - edema
Familial hypercholesterolemia - hyperlipidemia type IIA

42. trinucleotide repeat for huntingtons
The triphosphate bond
Malapsorption syndromes like sprue or CF or mineral oil intake
Nissl body - enzyme and NTs
CAG

43. What is the defect in fructose intolerance and What does it cause
MRNA - tRNA
Unmethylated - newly synthesized - HNPCC
Transmitted only through mother - all offspring of affected females may show signs of disease
Aldolase B - AR - fructose 1P accumulates causing a dec in availabel phosphate which inhibts glycogenolysis and gluconeogenesis leading to hypoglycemia - cirrhosis - jaundice and vomiting

44. Which are the acidic amino acids
In cytosol - oxaloacetate to phosphenolpyruvate - requires GTP
Asp and Glu
Glycogen and FFA oxidation; glucose conserved for final sprinting
Glucose 6 phosphate dehydrogenase (G6PD)

45. What is the fxn of vit D
Inc intestinal absorption fo calcium and phosphate - inc bone resorption
Bruton's agammaglobulinemia - wiskott - aldrich - fabrys disease - G6PD def - ocular albinism - Lesch - Nyhan syndrome - Duchenne and Becker Muscular Dystrophy - hunter's syndrome - hemophilia A and B
NAD+
Liver and beta cells of pancreas - low affinity - high Km - high capacity - high Vmax - induced by insulin

46. Type IV BM
Liver and leafy veggies
4 under the floor
Malapsorption syndromes like sprue or CF or mineral oil intake
Bind 30s subunit preventing attachment of aminoacyl - tRNA

47. What is the treatment for dec affinity of cystathionine synthase for pyroxidal phosphate
CTG
Pseudomonas and s aureus
D2 = ergocalciferol - ingested from plants D3 = cholecalciferol - ingested from milk - formed in sun exposed skin
Inc vit B6

48. What lab value can distinguish orotic aciduria from ornithine transcarbamoylase def?
Not all individuals with a mutant genotype show the mutant phenotype
OTC has hyperammonemia - orotic aciduira does not
Acetyl - CoA carboxylase (ACC)
Neonatal hemorrhage with inc PT and PTT - but nl bleeding time - can also occur after prolonged use of broad spectrum Abx

49. Which enzyme involved in RNA synthesis does not require a template
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
III - joint dislocation - anuerysms - organ rupture
Carbomoyl phosphate synthetase I
Poly A polymerase - signal is AAUAA

50. What shape does the RNA generate during splicing and why?
Active secretion in lungs and GI - reabsorbs in skin
Particular sequence of DNA where replicatino begins - may be single of multiple
Lariat shape in order and remove intron precisely and join 2 exons
TTP