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Flashcards in BIOCHEM Deck (11):
1

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)

2

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)

3

$$$ 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

4

What is the biologically active form of folic acid?

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

Tetrahydrofolate

N-methyl folate

5

What are the characteristics of oflic acid deficiency?

  • Neural tube defect
  • Growth failure
  • Megaloblastic anemia

6

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

7

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?

8

What is vitamin B12?

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

9

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

10

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)

11

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