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Flashcards in BIOCHEM Deck (11):

Where does the amino acid attach to tRNA?

CCA - Can Carry Amino acids


  • CCA-OH at 3' end
  • Covalently bound
  • Aminoacyl-tRNA synthetase uses ATP to attach the correct amino acid
  • Anticodon of tRNA reads the codon on mRNA at the opposite end (top end of clover)


Antibiotics that are inhibitors of prokaryotic protein synthesis at the 50S ribosome:

"Buy AT 30, CCELL at 50"

  • Aminoglycosides (Gentamicin, Tobramycin)
  • Tetracycline


  • Chloramphenicol
  • Clindamycin
  • Erythromycin (a macrolide)
  • Lincomycin
  • Linezolid (23S RNA)
  • Streptogramins
  • Macrolides (Azithromycin, Clarithromycin) (23S RNA)


$$$ In what metaboli creactions is folic acid (B9) involved?

  • Synthesis of urines (A,G) and thymine (T) -> these nitrogenous bases are important for DNA and RNA synthesis
  • Converted to tetrahydrofolate (THF), a conenzyme for 1-carbon transfer/methylation reactions


What is the biologically active form of folic acid?

What is the intracellular storage form of folic acid (folate)


N-methyl folate


What are the characteristics of oflic acid deficiency?

  • Neural tube defect
  • Growth failure
  • Megaloblastic anemia


What is megaloblastic anemia

Deficiency in which 2 vitamins cause megaloblastic anemia?


How do you determine which one it is caused by?

A type of macrocytic (large RBC) anemia characterized by an elevated number of megaloblasts in the marrow


Folate and B12


Decreased serum level of either


How much folate should a sexually-active woman of childbearing age take in order to prevent neural tube defects?


What results from excess of folate? Why?

0.4 mg of folic acid a day (4 grams if at high-risk for neural tube defects)


B12 deficiency results because this vitamin is used in making tetrahydrofolate?


What is vitamin B12?

  • Cobalamin
  • Cofactor for homocysteine methyltransferase (transfers CH3 groups as methylcobalamin) and methylmalonyl-CoA mutase


What metabolic reactions is vitamin B12 involved?

  • Homocysteine and methyl-THF -> methionine and THF (required for SAM to function)
  • Methylmalonyl CoA (coenzyme A) -> succinyl CoA


What is teh biologically active form of B6 (pyridoxine)

What is the metabolic function of  B6?

What drug can lead to a deficiency of B6 as well as B3?

  • Pyridoxal phosphate
  • Pyridoxal phosphate is a coenzyme for numerous enzymes including those of amino acid metabolism (transaminations and deaminations)


What drug can lead to a deficiency of B6 as well as B3?

What are the clinical findings of a B6 deficiency?

  • Isoniazid (for TB)
  • Same as riboflavin deficiency + Convulsions (creates GABA), hyperirritability, and peripheral neuropathy