Chapter·BiochemistryTranscription/translation

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1

A 45-year-old man presents with a hereditary condition affecting iron metabolism. The condition is caused by mutations in a gene that normally stimulates hepatic production of hepcidin, a hormone that downregulates iron absorption by inhibiting ferroportin (an iron transporter) on enterocytes. Due to this genetic defect, the patient has developed iron overload. He presents with skin hyperpigmentation, fatigue, joint pain, and diabetes mellitus. Laboratory studies show elevated serum ferritin and transferrin saturation. The patient is also developing early signs of cardiovascular complications from iron deposition. What would be the first cardiac manifestation in this patient?

APreload: decreased, cardiac contractility: unchanged, afterload: increased

BPreload: decreased, cardiac contractility: decreased, afterload: decreased

CPreload: increased, cardiac contractility: increased, afterload: increased

DPreload: increased, cardiac contractility: decreased, afterload: increased

EPreload: increased, cardiac contractility: increased, afterload: decreased

2

Researchers are investigating oncogenes, specifically the KRAS gene that is associated with colon, lung, and pancreatic cancer. They have established that the gain-of-function mutation in this gene increases the chance of cancer development. They are also working to advance the research further to study tumor suppressor genes. Which of the genes below is considered a tumor suppressor gene?

AHer2/neu

BBRAF

CBCL-2

DJAK2

ERb

3

A 25-year-old male is brought to the emergency department by his friends after a camping trip. He and his friends were in the woods camping when the patient started experiencing severe right upper quadrant abdominal pain after foraging and ingesting some wild mushrooms about 3 hours earlier. The patient is lethargic on exam and appears jaundiced. He has scleral icterus and is severely tender to palpation in the right upper quadrant. He has scattered petechiae on his extremities. Liver function tests are: Serum: Na+: 134 mEq/L Cl-: 100 mEq/L K+: 4.2 mEq/L HCO3-: 24 mEq/L Urea nitrogen: 50 mg/dL Glucose: 100 mg/dL Creatinine: 1.4 mg/dL Alkaline phosphatase: 400 U/L Aspartate aminotransferase (AST, GOT): 3278 U/L Alanine aminotransferase (ALT, GPT): 3045 U/L gamma-Glutamyltransferase (GGT): 100 U/L The most likely cause of this patient’s clinical presentation acts by inhibiting which of the following molecules?

ARNA polymerase II

BRNA polymerase III

CTopoisomerase

DRNA polymerase I

EProkaryote RNA polymerase

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