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. What is the order of collagen synthesis - just the terms of the intermediate forms?
Biotin; cofactor for carboxylation; pyruvate carboxylase (turning pyruvate to oxaloacetate) - acetyl coA carboxylase (acetyl coA to malonyl Co A) - and proprionyl coA caroboxylase for (propionyl CoA to methylmalonyl coA)
CNS defects - mental retardation - death - feeding difficulties - vomiting - hypoglycemia; thiamine
Preprocollagen - procollagen - tropocollagen - collagen
fastest sugar

2. What is the product of odd chain fatty acid synthesis? How does it return to TCA cycle? What cofactor is required?
Metabolizes them with transferase enzymes to acetyl coA
Methionine is only encoded by AUG
Proprionyl coA; through methylmalonyl coA; B12
Do an RT PCR (reverse transcriptase)- RT the RNA first - then PCR the DNA

3. What enzyme is deficient in classic galactosemia? symptoms? treatment?
Positive on phosphofructokinase 1 and negative on fructose 1 -6 bisphosphatase
Limit protein in diet; give benzoate or phenylbutyrate Which bind amino acids and lead to excretion - lactulose (hydrogen ion binds to ammonia to make excretable ammonium) and neomycin (to kill bacteria that release ammonia from aa)
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
Galactose 1 phosphate uridyltransferase (GALT) results in an accumulation of toxic substances; failure to thrive - jaundice - hepatomegaly - infantile cataracts - mental retardation; exclude galactose and lactose from diet

4. Fatty acid coA synthetase is used in FA...
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
Vincrstine (vinca alkaloids) and paclitaxel
degradation
Because cells of mononuclear phagocytic are esp rich in lysosomes

5. What is the first step in glycolysis?
Phosphorylation of glucose
Ouabain
AD
fat

6. What does fructose 6 phosphate do - depending On what?
Pyruvate carboxylase (pyruvate to OXA) (mit) - PEP carboxykinase (OXA to PEP) (cyt) - Fructose 1 -6 bisphophatase (fructose 1 -6 bisphosphate to fructose 6 P) (cyt) and glucose 6 phosphatase (in ER); glucose 6 phosphatase
Codons may encode same amino acid since there are only ~20 aa
This depends on if phosphofructokinase 1 is active and this depends on whether or not fructose 2.6 bisphophate is activating it or not - this can only occur if PFK 2 is on and not FBPase 2. then fructose 6 phosphate will participate in glycolysis. Ot
Promoter binds RNA Pol II and is very close (25 bases) to initiation site and is AT rich; enhancer/silencers bind TFs only - can be located close or far and regulate gene expression but not specifically initiation; transcription

7. Which lysosomal storage diseases have enzymes that are def in cells that are neuronal mostly?
Neimann pick and tay sachs
A topoisomerase II
Mitochondrial inheritance
Carbomyl phoshpate synthetase I

8. Coris glycogen storage disease has...
Bacteria produce lactate acid and gases from lactose and produce acidic diarrhea and bloating
normal lactate levels
Rb
Ornithine transcarbomyalse; orotic aciduria; X linked recessive; autosomal recessive

9. What are the clinical findings in edwards syndrome?
Thick mucus plugs lungs recurrent pulmonary infections (pseudomonas and aureus) - chronic bronchitis - bronchiectasis (which can lead to cor pulmonale!); biofilms form on resp tract
AD
Cell signaling defect in FGF receptor resulting in dwarfism and short limbs with normal head and trunk; AD
Mental retardation - rocker bottom feet - micrognathia (small jaw) - low set ears - clenched hands with polydactyly - congenital heart disease

10. How many calories does one gram of protein generate? carb? fat?
Steroid synthesis and detoxification
Mitosis then Interphase (G1 - S - G2); in G1 is presynthesis phase - S is synthesis phase (DNA rep. etc) - G2 is premitotic (making of MT spindle etc)
4 -4 -9
Presence of normal and mutated mtDNA (like mosaicism except in mit)

11. What do statins inhibit?
HMG CoA reductase
Arginne
teratogenic
All clathrin

12. In the fasting state - What ensures that the pyruvate doesnt get used for TCA cycle?
All clathrin
Biotin
The products of FA oxidation (Acetyl CoA and NADH) phosphorylate pyruvate deyhdrogenase Which inactivates it
Differentiation of cells - vision in reduced light (retinol makes up rhodopsin cells) - antioxidant

13. What are the glucogenic and ketogenic amino acids?
Ile - Phe - Thr - Trp
Carnitine shuttle
Abnormal glycogen metabolism results in accumulation of glycogen in cells
NADPH oxidase; CGD

14. What are the three branched aa?
2 -4 dinitrophenol - aspirin - and thermogenin (in brown fat)
Adrenal medulla
Isoleucine - valine - leucine
HMG CoA synthetase; HMG CoA reductase

15. What are the clinical symptoms of duchennes muscular dystrophy?
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
Arg and his
is asymmetric
XR - iduronate sulfatase

16. What aa does tyrosine come from?
Excess ATP and dATP has negative feedback inhibition on ribonucleotide reductase Which results in decreased DNA synthesis and thus decreased lymphocyte count
Phenylaline
UV nonionizing radiation causing thymidine dimers
No protein!

17. What is a robertsonian translocation? What does it mean if its balanced?
Inbit Na+K+ ATPase; Cardiac glycosides
Testing for antigen - antibody reactivity; can either add an antibody to a persons blood sample to see if there is binding or add an antigen to a persons blood sample to see if there immune system recognizes it; close to 100% for both; HIV eliza - an
Its When two acrocentric chromosomes combine their long arms (and short arms disappear); When the translocation is functional
32 or 30; malate aspartate shuttle or glycerol 3 phosphate shuttle; heart/liver and muscle

18. How do you treat fructose intolerance?
Gets converted to pyruvate via the Cori cycle in the liver
Biotin (vit B7) and Vit K
Decrease intake of fructose and sucrose (fructose and glucose)
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

19. What are rotenon - CN - antimycin A - CO?
Block Electron transport
Methionine is only encoded by AUG
3 hydrogen bonds; 2 hydrogen bonds
Cystic Fibrosis (CFTR gene)

20. What is the other name of Vitamin A? What is its source?
both liver and muscle (unlike glucagon)
Lysine and arginine; basic
Retinol; Beta carotenes (dark and yellow vegetables)
P53 and Rb; p53 activates BAX Which inhibits BCL2 When there is DNA damage - Rb phosphorylation allows progression into S phase

21. Achondroplasia is associated with advanced ________ age
CPSII
Using serine (which turns into glycine after reaction)
paternal
Excess ATP and dATP has negative feedback inhibition on ribonucleotide reductase Which results in decreased DNA synthesis and thus decreased lymphocyte count

22. What does ultrasound show in Downs?
Oxygen!
Hemorrhage with increased PT and PTT time but normal bleeding time
Fat malabsorption (CF) and abetalipoproteinemia (damage takes up all antioxidants)
Increased nuchal translucency

23. What is the most common disorder of the urea cycle? What is the result? What is its mode of inheritance? What is the mode of inheritance of the other urea cycle enzyme def?
AD: yes! most common presentation; very rare (700 mg/dl cholesterol level!)
Ornithine transcarbomyalse; orotic aciduria; X linked recessive; autosomal recessive
Double strand breaks; nonhomologous end joining
5' end; 3' end

24. Can a disorder be congential but not hereditary?

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

25. What is needed for glycolysis to continue? How is this provided in aerobic glycolysis? anaerobic?
B hydroxybutyrate - acetone - acetoacetate; beta hydroxybutyrate; beta hydroxybutyrate
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
NAD+; through ETC you produce NAD+; through production of Lactate from pyruvate you create lactate
Presence of normal and mutated mtDNA (like mosaicism except in mit)

26. At What point is the amino acid correspondence to the mRNA code finalized?
In the charging reaction! for this reason aminoacyl tRNA synthetase double checks
Enriched whole grain cereals and other things; thiamine; malnutrition (nonenriched white processed bread and rice) and alcohol second to malnutrition
Glucosekinase to glucose 6 P
32 or 30; malate aspartate shuttle or glycerol 3 phosphate shuttle; heart/liver and muscle

27. other than in the kidney - Where else are gluconeogenesis enzymes found?
Autosomal Dominant; NF1 and mit. diseases (variable expression) - ?
ATP synthase - ATP- ADP translocase - ETC
Kidney and intestinal epithelium
Self mutilation - aggression - mental retardation - gout - hyperuricemia - choreathetosis

28. Which drug blocks the Na+K+ pump by blocking the K+ site?
all are diseased!
Ouabain
Met - arg - val - his
glycogenolysis

29. What is the source of ATP after a meal?
Glycolysis and aerobic respiration
Renal calculi of uric acid (replaces uric acid in excretion)
degradation
Edwards

30. What type of exonuclease activity does DNA polymerase I have? in What organisms is it found? What is it used for?

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

31. What is the mc chromosomal disorder?
Downs
When water is pulled in; polyols (sugar alcohols); cataracts - retinopathy - peripheral neuropathy all seen in chronic hyperglycemia in diabetes
Developmental delay - gargoylism - airway obstruction (d/t short neck) - corneal clouding - CAD - hepatosplenomegaly
Lipoprotein lipases take FA from VLDL and chylomicrons Which are then combined with glycerol 3 P (a carb intermediate) to make triacylglycerol

32. Where does gluconeogenesis occur?
Acetyl CoA carboxylase
Liver mit and liver cytosol
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
Catalyze gamma carboxylation of glutamic acid residues on coag factors so they can bind to Ca complex

33. Which RNA polymerase synthesizes rRNA? where?
Very Poor Carb Metabolism (Von Gierke - Type 1 - Pompes - Type II - Cori's - Type III - McArdles disease - Type IV)
fastest sugar
I; nucleolus
NADH - Acetyl CoA - ATP; NAD+ - ADP and Ca2+

34. Name two antineoplastic drugs that work by inhibiting the mitotic spindle by MT blocking.
Pernicious anemia; older - mentally slow european woman who is anemic and icteric with a smooth shiny tongue and has broad based shuffling gait
Vincrstine (vinca alkaloids) and paclitaxel
Phenylalanine build up
Converts it to citrulline

35. What is the precursor in the skin that the sun turns to D3?
7 dehydrocholesterol
Decreased would healing; microcytic anemia (d/t decreased iron [not absorbable]; macrocytic anemia (d/t Fh4 not reduced)
Microvilli - muscle contraction - cytokinesis - adherens junctions
Catalase positive because they reduce their H2O2 and WBCs cant use that to make bleach; because the way they protect is by building a wall around the organisms with granulomas

36. Where does a majority of galactose in our diet come from?
By addition of mannose 6 phosphate to proteins in the Golgi
Lactose (glucose and galactose)
glucagon - insulin and epinephrine
Oral uridine administration; provides nucleosides and provides feedback inhibition

37. What enzyme is deficient in maple syrup disease? What does it result in?
Branched chain alpha keto acid dehydrogenase; inability to break down branched chain aa
Delayed wound healing - hypogonadism - decreased adult hair - dysgeusia - anosmia - and alcoholic cirrhosis - perioral rash
Gets converted to glycerol 3 P Which is then converted to DHAP Which then can enter glycolyis
Gauchers; hepatosplenomegaly - aseptic necrosis of the femur - bone crises - Gauchers cells - crumpled tissue paper looking (fibrillar appearing macrophages in liver - spleen - b.m.)

38. What is the difference between a kinase and a phophorylase?
By activating protein phosphatase Which both dephosphorylates glycogen phosphorylase (deactivating) and dephosphorylates glycogen synthase (activating it )
Both add phosphate; phosphorylase uses no ATP and inorganic phosphate
HVA
NADH - Acetyl CoA - ATP; NAD+ - ADP and Ca2+

39. How do you detect the different reasons that cause cobalamin def?
Schilling test
Increased NADH causes lactate production and pyruvate dehydrogenase def causes increased lactate (d/t thiamine def that often occurs with alcoholics)
COP II
Steroid synthesis and detoxification

40. What is the purpose of the PCR?
7 dehydrocholesterol
To amplify a specific desired fragment of DNA
1) if it is stable/labile or permanent 2) intact BM and 3) intact ECM
No

41. How does a kwashiokor patient present?
Limit dextrans
Glycolysis and aerobic respiration
Cafe au lait spots - optic pathway gliomas - lisch nodules - scoliosis - neural tumors
Malnutrition - edema (hypoalbuminemia) - anemia liver (fatty change) - diarrhea d/t no brush border enzymes (no protein!)

42. If a cell has a hyperchromatic or condensed nucleus is it undergoing transcription etc?
Decreased substrate for gluconeogenesis (pyruvate to lactate and not oxaloacetate); and pyruvate doing only lactic acidosis and not glycolysis
Pyridoxine; converted to pyridoxal phsophate used in transamination reaction - decarboxylations - heme synthesis - niacin synthesis from trp - glycogen phosphorylase - cystathionine synthesis - NT synthesis
No
A lysosomal storage disease; mannose 6 phosphate can not be added to lysosomal proteins

43. What are the types of lipids found in the plasma membrane?
Phospholipids - sphingolipids - glycolipids
Downs
Imprinting Dx's: prader Willi and Angelmann
Intestine - renal - bone

44. What is the rate determining enzyme in glycogen synthesis?
Phosphofructokinase 1; fructose 1 phosphate to fructose 1 -6 bisphosphate; enhancers: AMP - fructose 2 -6 Bisphosphate; downregulators: citrate - ATP
Glycogen synthase
SER and mitochondria; NADPH
VMA

45. What are the symptoms of williams syndrome? What is the pathogenesis?
Pyruvate dehydrogenase; ATP - NADH - acetyl CoA
Distinctive elfin faces - mental retardation - hypercalcemia d/t sensitivity to vit D - well developed verbal skills and extreme friendliness - CV problems
Pernicious anemia; older - mentally slow european woman who is anemic and icteric with a smooth shiny tongue and has broad based shuffling gait
Aldolase B

46. What type of proteins have AD mode of inheritance?
Cu; hydroxylation
Structural (constitutively active)
DNA dependent RNA polymerase
Cylindrical made up of a helical array of polymerized alpha and beta tubulin dimers - each dimer has 2 GTP bound

47. In What syndrome is HGPRT deficient? What is the inheritance pattern?
UV nonionizing radiation causing thymidine dimers
Lesch Nyhan syndrome; X linked recessive
Chediak Higashi Syndrome; decreased phagocytosis results in recurrent pyogenic infections - partial albinism - and peripheral neuropathy
Inability to transport LCFA into mitochondria results in their build up and causes weakness - hypotonia And HYPOKETOTIC HYPOGLYCEMIA

48. How do you differentiate causes of megaloblastic anemia?
Liver; berry aneurysms (d/t hypertension!) - and mitral valve prolapse
Orotic aciduria megaloblastic anemia can not be corrected with folic acid or vit B12
(cofactor for 100+ enzymes!) needed for zinc fingers transcription motif - collagen synthesis - alcohol metabolism
25 OH D3; 1 -25 (OH)2 D3 (Calcitriol)

49. What type of aa are histones made of? are they acidic or basic?
Phosphoenolpyruvate; pyruvate kinase; fructose 1 - 6 BP; ATP - alanine
Stored ATP - creatine phosphate - anaerobic glycolysis; as distances increase - ATP is obtained from additional resources; above plus ox phos
Chromosomal imbalance (downs for ex)
Lysine and arginine; basic

50. What is the first step in fatty acid synthesis? Where does it occur? Where does triacylglycerol synthesis occur?
Either salvage by HGPRT and PRPP or converstion to xanthine and then to uric acid by xanthine oxidase
Limit protein in diet; give benzoate or phenylbutyrate Which bind amino acids and lead to excretion - lactulose (hydrogen ion binds to ammonia to make excretable ammonium) and neomycin (to kill bacteria that release ammonia from aa)
aldose reductase
Citrate shuttle in the inner mitochondrial membrane transports acetyl coA into the cytoplasm; liver; liver and adipose tissue

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