Test your basic knowledge |

USMLE Step 1 Biochemistry

Subjects : health-sciences, usmle-step-1

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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. After the PCR reaction - How do you actually visualize the DNA?
Malnutrition - edema (hypoalbuminemia) - anemia liver (fatty change) - diarrhea d/t no brush border enzymes (no protein!)
normal lactate levels
Do agarose gel eletrophoresis to separate the different sizes of the PCR products (sizes id the the fragment)
Mebendazole and thiabendazole

2. What control over pyruvate kinase does insulin have?
Galactose gets converted to galactose 1 Phosphate by galactokinase Which then gets turned into glucose 1 phosphate by Galactose 1 Uridyl Transferase (GALT) Which also produces UDP Gal Which is used for lactose production in the breast; the fate of gl
Protein Kinase A inhibits pyruvate kinase also ATP and alanine have negative effects on pyruvate kinase
It induces its action!
Niacin treatment for hyperlipidemia; facial flushing

3. What reactions occur in the mitochondrial matrix? mit inner membrane?
TCA cycle - FA oxidation - acetyl coA production; ox phos
25 OH D3; 1 -25 (OH)2 D3 (Calcitriol)
Cysteine; tyrosine
Vomiting - rice water stools - garlic breath

4. How do WBCs of CGD patients do some damage?
Kartaganer's aka ciliar dyskinesia; lack of dynein arm ATPase
They use the H2O2 produced by some bacteria to produce bleach with myeloperoxidase Which they still have
Alanine (through pyruvate) - aspartate (through OXA) - glutamate (alpha ketoglutarase); TCA
Type I collagen; AD

5. What is needed for glycolysis to continue? How is this provided in aerobic glycolysis? anaerobic?
Cystathionine (which then goes to cysteine) via cystathionine reductase; B6
Glucose 6 phosphate dehydrogenase
NAD+; through ETC you produce NAD+; through production of Lactate from pyruvate you create lactate
Hexosaminidase A; GM2 ganglioside

6. Where are cilia found? What symptoms are associated with kartageners syndrome?
Arginine
Vit D and K
In the reproductive tract and in the resp tract; infertility - bronchiectasis and recurrent sinusitis - associated with situs inversus
in hepatocytes

7. What is the exception to the nonoverlapping/commaless aspect of the genetic code?
Some viruses
Telomerase; an RNA polymerase that uses a RNA template to add DNA to the end of shortening 3' ends
Defective neutral amino acid transporter on renal and intestinal cells; AR
Formation of a proton gradient that is then used to create ATP through ATP synthase

8. What is DNA gyrase?
In the reproductive tract and in the resp tract; infertility - bronchiectasis and recurrent sinusitis - associated with situs inversus
A topoisomerase II
allosteric regulation
RER in nucleus (synthesize NTs)

9. What converts dihydrobioterin back to tetrahydrobioterin factor? What energy carrier is used? in What reactions is this cofactor used?
Mannose
Dihydropterin reductase; NADP+; phenylalanine to tyrosine and tyrosine to DOP
Tetrahydrofolates
Fructose bisphosphatase 2

10. What carries Acyl (as energy)?
Coenzyme A and lipoamides
Catalyze gamma carboxylation of glutamic acid residues on coag factors so they can bind to Ca complex
Back up of pyruvate and alanine and thus lactic acidosis occurs; can be d/t alcoholism (vit B1 def)
By turning it into fructose - but sorbitol first; glucose to sorbitol via aldose reductase and sorbitol to fructose sorbital dehydrogenase

11. What is the difference between rickets and osteomalacia?
Decreased phenylalanine - increase tyrosine
Chronic pancreatitis leads to type 1 diabetes - pancreatic insufficiency leads to ADEK deficiencies - malabsorption and steatorrhea - blocked gallbladder ducts leads to secondary biliary cirrhosis
Increased CPK and muscle biopsy
Osteomalacia is vit D def seen in adults and causes bowed legs and results in increased fractures

12. Where is anaerobic glycolysis used often?
Fructose 1 -6 bisphosphatase
RBCs - renal medulla - leukocytes - lens - testes - cornea
When the 2nd hit of the allele is What causes the disease; sporadic retinoblastoma
Myoclonus epilepsy

13. Name two diseases that have to do with elastin; discuss their pathogenesis.
Homocysteine methyltransferase - cystathionine reductase - decreased affinity of cystathionine reductase for pyridoxal phosphate; AR
Mucus secreting goblet cells - ab secreting plasma cells - nt secreting neurons
Glycerol and propionyl coA; lactate and alanine
Marfans and emphysema; marfans is a fibrillin protein defect - fibrillin is a supporting protein in tropoelastin scaffolding and results in aorta - skeletal and eye defects; emphysema is due to a deficiency in the function of alpha 1 antitrypsin

14. What is the first enzyme step in glycogenolysis? What activates it ? inactivates?
Lactose (glucose and galactose)
Glycogen phosphorylase; phosphorylation and dephosphorylation
N5N10 methylene THF
Hexosaminidase A; GM2 ganglioside

15. _____________ prevents fluidity of plasma membrane
Biotin
Arginine
SAM
high cholesterol

16. Where is type 1 collagen found?
Alkaptonuria; ochronosis
Bone - Skin - Tendon - dentin - fascia - cornea - late wound repair
paternal
Cu; hydroxylation

17. What two compounds provide the two N's of urea? What else is in urea other than two NH2's?
Imprinting Dx's: prader Willi and Angelmann
Glutamate and aspartate; CO2 provides an ketone
Smoking (FR takes up all the antioxidants); diets lacking fruit
When the amino acid is covalently binded to its corresponding tRNA; Aminoacyl tRNA synthetase; ATP; translation

18. When is phenylketonuria screened? why?
2-3 days after birth because maternal enzyme during fetal like might still be there
Pyruvate to alanine (to carry amino groups to liver) - pyruvate to OAA for gluconeogenesis (or replenish for TCA cycle) - acetyl coA (for TCA cycle transition or FA or chol. synthesis) - or the end of anaerobic glycolysis
Phenylalanine
cell cycle events

19. Where is antioxidant activity of Vit E most important?
Nucleoside is just the ribose plus the base; nucleotide is the ribose plus the base but the phosphate bond
Neurons and RBCs
B12 and folate; B12; washed out
Branched alpha ketoacid dehydrogenase

20. What are the results of the pregnancy screen for Downs?
Ceramide trihexoside
Respiratory burst - P450 - and glutathione reductase
Myoclonus epilepsy
Decrease AFP - increased BCHG - decreased estriol - increased inhibin A

21. Kwashiokor patients are not...
Actin/myosin - MT - intermediate filaments
Double stranded RNA is created that is complementary to the mRNA of interest and When inserted into cells the strands separate and attach to the mRNA preventing it from being translated
Cell signaling defect in FGF receptor resulting in dwarfism and short limbs with normal head and trunk; AD
calorie deficient

22. Where are secreted proteins synthesized? Where are cellular/organellar proteins synthesized?
Fatty acid (acyl coA) oxidation to acetyl coA; increase in dicarboxylic acids - and decreased glucose and ketones
usually present late
RER; free ribosomes
Cylindrical made up of a helical array of polymerized alpha and beta tubulin dimers - each dimer has 2 GTP bound

23. Glucokinase has a LOW affinity (high Km) and...
high Vmax
Glucagon - insulin and epinephrine
Exons
Thymidylate synthase; 5- Flourouracil

24. What happens to homocysteine after converting a methyl?
A ketone
(cofactor for 100+ enzymes!) needed for zinc fingers transcription motif - collagen synthesis - alcohol metabolism
Fructose gets phosphorylated into fructose 1- P by fructokinase and then fructose 1P gets metabolized into DHAP or glyceraldehyde by aldolase B
Becomes methionine

25. There are 2 GTP per...
Some viruses
Starts before age 5 with with pelvic girdle weakness with use of Gowers maneuver to stand up - it then progresses superiorly with muscle weakness (type 1 and 2!); waddling duck gait; hyporeflexia; pseudohypertrophy of calf muscles d/t fibrofatty repl
tubulin dimer
Gets converted to glycerol 3 P Which is then converted to DHAP Which then can enter glycolyis

26. What antibiotic inhibits peptidyltransferase activity?
Limit dextrans
Branched chain alpha keto acid dehydrogenase; inability to break down branched chain aa
Decrease AFP - increased BCHG - decreased estriol - increased inhibin A
Chloramphenicol

27. What disease manifestations result in Prader Willi syndrome? is the deletion a result from the father or mothers chromosome?
Asp and glu; negatively
Mental retardation - obesity - short stature - hypogonadism - hypotonia - hyperphagia; father
Bendy bones seen in children due to decreased Vit D; craniotabes - skeletal deformities - growth retardation - rosary
Via fructose 1 P by fructokinase in the liver; as glucose 1 by being GALT- ed ;)

28. What enzyme is used in the oxidative phase of HMP shunt? nonoxidative?
2 NADH - 2 ATP - 2 pyruvate - 2H+ - 2H20
G6PD dehydrogenase; transketolases
CNS defects - mental retardation - death - feeding difficulties - vomiting - hypoglycemia; thiamine
Carbomyl phosphate synthetase I

29. What liver enzymes are increased in alcoholism? why?
HMP shunt (to NADPH) and glycogenolysis (as glucose 1 phosphate)
Pyruvate (through OXA); lactate - alanine - malate (and all other TCA intermediates through OXA) - glycerol - odd chain fatty acids yield propionyl coA Which can be converted to succinyl coA and enter as TCA cycle
AST (mit damage) - and GGT (d/t SER hyperplasia d/t induction of p450 generation)
Hexosaminidase A; GM2 ganglioside

30. What is the metabolism of fructose?
Glucokinase
reabsorbs
Fructose gets phosphorylated into fructose 1- P by fructokinase and then fructose 1P gets metabolized into DHAP or glyceraldehyde by aldolase B
DHF

31. What are the findings in maple syrup disease? What should be tried to be given as treatment?
Sphingomyelinase; sphingomyelin
Renal calculi of uric acid (replaces uric acid in excretion)
Tyrosine
CNS defects - mental retardation - death - feeding difficulties - vomiting - hypoglycemia; thiamine

32. What cofactor is required for lysyl oxidase cross linking? What reaction is required beforehand for crosslinking to occur?
Cu; hydroxylation
Fructose bisphosphatase 2
Adrenal cells (steroid synthesis) - hepatocytes (p450 detox)
Codons may encode same amino acid since there are only ~20 aa

33. What enzyme is deficient in galactokinase deficiency? What are the symptoms?
Galactokinase; galactose appears in blood and urine - sometimes infantile cataracts may present as failure to track objects or lack of a social smile
Liver and skeletal muscle
Because carbamaoyl phosphate is involved in both urea cycle and pyrimidine synthesis
Less; more

34. What are the glycogen storage disease? What they result in?
Tryptophan; melatonin
Abnormal glycogen metabolism results in accumulation of glycogen in cells
A folic acid analogue
'9+2' 9 pairs of microtubules connected by an axonemal dynein ATPase in a cylinder with 20 MTs in the center; the connecting ATPase allows bending and differential sliding

35. Which vitamin keeps Fh4 in its reduced form?
It inhibits conversion of DHF to THF by blocking dihyrdofolate reductase
Vit C
Shiga toxin and ricin (protein in castor beans)
Biotin

36. Which Hurlers is milder and presents with no corneal clouding?
Cartilage (including hyaline) - vitreous body - nucleus pulposus
Collections of abnormal mit collecting under sarcolemmal membranes and results in distortion of myofibrils
succinyl coA (and then to OXA)
XR - iduronate sulfatase

37. give an example of how phenylketonuria is pleiotropic.
Reticulin - skin - blood vessels - uterus - fetal tissue - early phase of granulation tissue
Vincrstine (vinca alkaloids) and paclitaxel
Cafe au lait spots - optic pathway gliomas - lisch nodules - scoliosis - neural tumors
Also have fair skin - blond hair - blue eyes - eczema

38. How do you treat fructose intolerance?
ATP synthase - ATP- ADP translocase - ETC
Decrease intake of fructose and sucrose (fructose and glucose)
Lactic acidosis and ketoacidosis
Hepatic fatty change

39. How are senescent cells different from some neoplastic and germ cells? What does this substance do?

Warning: Invalid argument supplied for foreach() in /var/www/html/basicversity.com/show_quiz.php on line 183

40. What is the function of Vitamin A?
HMG CoA reductase; converts HMG CoA to mevalonate
AD
Differentiation of cells - vision in reduced light (retinol makes up rhodopsin cells) - antioxidant
Increased G3P for TG synthesis - increased acetyl CoA (Fatty acid synthesis for TG synthesis) - and decreased oxidation of FA in the mitochondria due to alcohols toxicity on the mit

41. Glucokinase is a...
GTP: gluconeogenesis - OXA to phosphoenolpyruvate
Reserve supply of glucose in the fasting state - liver gives to the blood and skeletal muscle uses for itself
glutton
plasma membrane

42. Is heterochromatic more accessible or less accessible to TF? euchromatin?
ATP synthase - ATP- ADP translocase - ETC
Macroorchitism - big ears - big jaw - mental retardation (2nd mcc!) - mitral valve prolapse - long face
Less; more
Tyrosine; phenylaline

43. What syndrome is characterized by hyperextensible skin and joints - and bleeding? What is the most common reason? What are other clinical symptoms?
Either salvage by HGPRT and PRPP or converstion to xanthine and then to uric acid by xanthine oxidase
BM; laminins; most flexible; different aa composition
Nitric Oxide - creatinine - Urea
Ehler Danlos; type III collagen def; joint dislocation - berry aneurysm - ecchymoses - organ rupture

44. What goes on with G0 cell cycle phase?
hexokinase (glucokinase only found in liver and beta cells of pancreas)
Hungtington
Schilling test
Cells that are stable go in and out of the G1 to G0 Which is the stable/quiescent (can go into replication but dont) type of cells; cells that stay in G0 are permanent and can not enter G1

45. What Abs block the binding between aminoacyl tRNA and rRNA by binding the 30S ribosome?
Cells that are stable go in and out of the G1 to G0 Which is the stable/quiescent (can go into replication but dont) type of cells; cells that stay in G0 are permanent and can not enter G1
Aminoglycosides and tetracyclines
Arginne
They use the H2O2 produced by some bacteria to produce bleach with myeloperoxidase Which they still have

46. What is the first enzyme and step in ethanol metabolism? second step? What is a cofactor in both of these steps? What vitamin does this come from?
tubulin dimer
kidney
Alcohol dehyrogenase (alcohol to acetaldehyde); acetaldehyde dehydrogenase (acetaldehyde to acetate); NAD+; B3 (niacin)
HVA

47. What ensures that during gluconeogenesis all the ATP wont be used in glycolysis as youre producing it?
Dermatitis - glossitis - diarrhea
All clathrin
In hepatocytes; B6
Protein Kinase A inhibits pyruvate kinase also ATP and alanine have negative effects on pyruvate kinase

48. What are the two different ways you can insert genes into transgenic mice for experiments?
Lesch Nyhan syndrome; X linked recessive
Urine turns black on standing
Constitutive - random insertion of gene into mouse genome; conditional - targeted through homologous recombination
Sulfonamides - primaquine - dapsone - antiTB drugs - fava beans - LDL; RBCs

49. What are chromosomes? during What part of the cell cycle are they found? in What pathologic state would you see a lot of chromosomes?
Cell signaling defect in FGF receptor resulting in dwarfism and short limbs with normal head and trunk; AD
Cheilosis and corneal vascularization
Highly condensed forms of DNA; mitosis; neoplasia - highly dividing and thus hyperchromatic
5'--> 3'; prokaryote only; for removing RNA primer and filling it with DNA

50. How do you treat homocystinuria due to decreased affinity of cystathionine reductase to B6?
Tay Sachs - Niemann Picks - Gauchers
glutton
Back up of pyruvate and alanine and thus lactic acidosis occurs; can be d/t alcoholism (vit B1 def)
By giving high amounts of pyridoxal phosphate in the diet

Sorry!:) No result found.

Can you answer 50 questions in 15 minutes?

Major Subjects
Tests & Exams AP CLEP DSST GRE SAT GMAT	Certifications CISSP go to https://www.isc2.org/ PMP ITIL RHCE MCTS More...	IT Skills Android Programming Data Modeling Objective C Programming Basic Python Programming Adobe Illustrator More...	Business Skills Advertising Techniques Business Accounting Basics Business Strategy Human Resource Management Marketing Basics More...
Soft Skills Body Language People Skills Public Speaking Persuasion Job Hunting And Resumes More...	Vocabulary GRE Vocab SAT Vocab TOEFL Essential Vocab Basic English Words For All Global Words You Should Know Business English More...	Languages AP German Vocab AP Latin Vocab SAT Subject Test: French Italian Survival Norwegian Survival More...	Engineering Audio Engineering Computer Science Engineering Aerospace Engineering Chemical Engineering Structural Engineering More...
Health Sciences Basic Nursing Skills Health Science Language Fundamentals Veterinary Technology Medical Language Cardiology Clinical Surgery More...	English Grammar Fundamentals Literary And Rhetorical Vocab Elements Of Style Vocab Introduction To English Major Complete Advanced Sentences Literature Homonyms More...	Math Algebra Formulas Basic Arithmetic: Measurements Metric Conversions Geometric Properties Important Math Facts Number Sense Vocab Business Math More...	Other Major Subjects Science Economics History Law Performing-arts Cooking Logic & Reasoning Trivia

Test your basic knowledge |

USMLE Step 1 Biochemistry

Sorry!:) No result found.

Can you answer 50 questions in 15 minutes?

Let me suggest you:

Browse all subjects

Browse all tests

Most popular tests

Major Subjects

Tests & Exams

Certifications

IT Skills

Business Skills

Soft Skills

Vocabulary

Languages

Engineering

Health Sciences

English

Math

Other Major Subjects

Browse all subjects

Browse all tests

Most popular tests