Usmle biochemistry exam - Study guides, Class notes & Summaries

histones are rich in which 2 AA's - correct answer lysine & argenine Barr bodies (what, type of chromatin) - correct answer inactive X chromosomes heterochromatin (highly condensed, sterically inaccessible) less condensed, transcriptionally active, sterically accessible chromatin - correct answer euchromatin DNA methylation at CpG islands - correct answer represses transcription "CpG Methylation makes DNA Mute" DNA methylation (what is methylated and why?) - correct answer tem...

1. Q Which of the following statements if false? Select one: a. Heme (or protophoryrin ring) is synthesized from Succinyl-CoA and Glyicine. b. 65% of the enzymes have His-Arg-Cys-Glu-Asp in the active site. c. Hemoglobin can be given as an example of a molecule that exhibits allosterism. d. Bohr’s effect is observed in both Myoglobin and Hemoglobin. A d. Bohr’s effect is observed in both Myoglobin and Hemoglobin. 2 2. Q Glutathione peroxidase catalyzes which of the following type ...

1 Q A patient presents with blue sclera that results in an inability to form procollagen from pro-α chains. What disease does he have? A Osteogenesis imperfecta 2 Q List the four main phases of mitosis in order. A Prophase, metaphase, anaphase, and telophase 3 Q When does mitosis occur in the cell cycle? A Mitosis occurs after G2 and before G1 in the cell cycle 4 Q When does DNA synthesis occur in the cell cycle? A After G1 and before G2 in the cell cycle 5 Q

1 Q 2. Identify the metabolite that does NOT serve as a precursor of a dietarily essential amino acid: A. Alpha-ketoglutarate B. 3-phosphoglycerate C. Glutamate D. Aspartate E. Histamine A E. Histamine Histamine is a catabolite, not a precursor, of histidine. 2 Q 4. Select the CORRECT answer: The first reaction in the degradation of most of the protein amino acids involves the participation of: A. NAD+ B. Thiamine pyrophosphate (TPP) C. Pyridoxal phosphate D. FAD E. NAD+ and TP...

which histone ties DNA-histone nucleosome beads into more condensed structures? - Answer-H1 is DNA acidic or basic? - Answer-acidic what type of aa are histones made of? are they acidic or basic? - Answer-lysine and arginine; basic is heterochromatic more accessible or less accessible to TF? euchromatin? - Answer-less; more if a cell has a hyperchromatic or condensed nucleus is it undergoing transcription etc? - Answer-no what are chromosomes? during what part of the cell cycle ar...

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First Aid USMLE Step 1: Biochemistry Exam Study Questions and Answers What is a nucleoside? What is a nucleotide? Which are the purines? Which are the pyrimidines? - ANSWER-Side = base + (deoxy)ribose [sugar] Tide = base + (deoxy)ribose [sugar] + phosphaTe *Which are the purines?* ©EMILLECT 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/152 "pure as gold" = Adenosine, Guanosine *Which are the pyrimidines?* "CUT the pyramid" = Cytosine, Ur...

USMLE step 1 – biochemistry Exam Study Guide Solutions infant with somnolence, vomiting, cerebral edema, decreased BUN, hyperammonemia - ANSWER- ornithine transcarbamoylase deficiency infantile cataracts, doesn't track objects, absent social smile - ANSWER-galactokinase deficiency infantile cataracts, hepatomegaly, jaundice, failure to thrive - ANSWER-uridyltransferase deficiency causes of Down syndrome - ANSWER-1) meiotic nondisjunction (95%) 2) unbalanced robertsonian translocation...

infant with somnolence, vomiting, cerebral edema, decreased BUN, hyperammonemia - Answer-ornithine transcarbamoylase deficiency infantile cataracts, doesn't track objects, absent social smile - Answer-galactokinase deficiency infantile cataracts, hepatomegaly, jaundice, failure to thrive - Answer-uridyltransferase deficiency causes of Down syndrome - Answer-1) meiotic nondisjunction (95%) 2) unbalanced robertsonian translocation (extra arm on Ch 21) 3) mosaic trisomy 21 treatment ...