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FREE USMLE AND STUDY GAMES ABOUT USMLE BIOCHEM
EXAM QUESTIONS
Actual Qs and Ans Expert-Verified Explanation
This Exam contains:
-Guarantee passing score -300 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: What property of water most contributes to its ability to dissolve compounds?
Answer:
Hydrogen bonds
Question 2: What is used to proofread human DNA?
Answer:
3' -> 5' Exonuclease activity of DNA poly Delta Question 3: What initiates the promoter in the prokaryotic cell?What may be required to terminate transcription?
Answer:
intiate: Sigmaterminate: Rho + stem & loop (or UUUUU + stem & loop)
Question 4: (2) ways to make TG in the liver
Answer:
- Glucose enters liver: Glucose -> DHAP + Glycerol-3-P DH -> Glycerol-3-P + 3 FA CoA -> TG
- Glycerol enters liver: Glycerol + Glycerol Kinase -> Glycerol-3-P + 3 FA CoA -> TG
Question 5: What favors gene expresson--histone acetylases or deacetylases? Why?
Answer:
histone acetylases - open hisones anything that condenses or bulks chromatin does not favor gene expression Question 6: What tissues use receptor: GLUT 4?
Answer:
Muscle Adipose Question 7: Dx: Hyperextensible, fragile skin, hypermobile joints, vericose veins, arterial and intestinal ruptures Deficiency?
Answer:
Ehlers-Danlos Deficiency: Lysine hydroxylase collagen deficiency secondary to lack of copper
Question 8: What parts of the TCA cycle deals with Gluconeogenesis?
Answer:
OAA & Malate Question 9: What does bacteria do to protect its DNA? How does it destroy foreign DNA (bacteriophage)?
Answer:
it Methylates its DNA Restriction endonucleases Question 10: Accumulation of what in the liver triggers it to make fat? What is needed?
Answer:
Acetyl CoA Need Energy (ATP)
Question 11: Which receptor is associated w/ Protein Kinase C?
Answer:
IP3 (Gq)
Question 12: Most prevalent AA in collagen? Two other common AA in collagen?
Answer:
Glycine Proline & Lysine
Question 13: What occurs to collagen after it is hydroxylated? In what part of the cell? What is formed here? Name?
Answer:
Glycosylated in Golgi Triple helix (Procollagen)
Question 14: amino acid precursor to GABA
Answer:
Glutamic Acid
Question 15: What are two essential items needed to make ATP from NADH?
Answer:
1) Oxygen 2) Mitochondria (for ETC)
Question 16: What glycogen storage Dz has debranching enzymes?
Answer:
Cori's Dz
Question 17: removes a phosphate from a substance
Answer:
Phosphatase Question 18: Which Complex in the ETC uses Oxygen? Another name for thtis complex? What else is needed for this Complex? What 2 compounds inhibit this Complex?
Answer:
Complex IV (Cyto a/a3) copper Cyanide & CO Question 19: Which enzyme in the TCA cycle is in the inner mitochondrial membrane versus the matrix of the mitochondria?
Answer:
Succinate Dehydrogenase
Question 20: 2 amino acids that are the precursors for catecholamines
Answer:
Phenylalanine Tyrosine
Question 21: Which base nucleotide has an extra methyl group?
Answer:
Thymine(THYmine = meTHYl) Question 22: Dx: 48-yo man w/ recessive condition is at high risk for deep vein thrombosis and has had replacement of ectopic lenses; no evidence of anemia. Enzyme that is deficient? What AA would be in excess?
Answer:
Homocysteinuria Enzyme: Cystathionine Synthase AA: Methionine
Question 23: name 5 Autosomal Dominant diseases
Answer:
FH-MAN Familial Hypercholesterolemia; Huntingtons; Marfans; Acute Intermittent Porphyria; NF-1 Question 24: What type of bonds are there in alpha-helix and beta-sheet proteins?
Answer:
Peptide bonds that participate in H+ bonding Question 25: What is usually the common problem in the Autosomal Dominant diseases?
Answer:
Structural protein damage Question 26: Dx: Painful abdomen; Pink urine (Port-wine urine); Polyneuropathy; Psychological disturbances
Answer:
- P = Porphyria
Question 27: What enzyme of glycolysis is only in the liver and is induced by insulin? Level of affinity of this enzyme?
Answer:
Glucokinase Low affinity = High Km = high Vmax
Question 28: Describe the 4 levels of protein shape
Answer:
Primary - Amino Acids Secondary - folded AA into a-helix or b-sheet Tertiary - 3-D the secondary
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