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)
Tetrahydrofolate
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
