The Central Dogma of Molecular Biology REPLICATION
What is required for translation? • mRNA • Ribosomes • ‘Charged’ tRNA • Energy (GTP) Inhibitors of translation: • Streptomycin (small ribosomes)
The genetic code, part 1 Universal Redundant (degenerate)
Second base U C A G First base U UUU Phe UUC Phe UUA Leu UUG Leu UCU Ser UCC Ser UCA Ser UCG Ser UAU Tyr UAC Tyr UAA STOP UAG STOP UGU Cys UGC Cys UGA STOP UGG Trp C CUU Leu CUC Leu CUA Leu CUG Leu CCU Pro CCC Pro CCA Pro CCG Pro CAU His CAC His CAA Gln CAG Gln CGU Arg CGC Arg CGA Arg CGG Arg A AUU Ile AUC Ile AUA Ile AUG Met ACU Thr ACC Thr ACA Thr ACG Thr AAU Asn AAC Asn AAA Lys AAG Lys AGU Ser AGC Ser AGA Arg AGG Arg G GUU Val GUC Val GUA Val GUG Val GCU Ala GCC Ala GCA Ala GCG Ala GAU Asp GAC Asp GAA Glu GAG Glu GGU Gly GGC Gly GGA Gly GGG Gly The genetic code, part 2 Phe = phenylalanine, Leu = leucine, Ser = serine, Tyr = tyrosine, Cys = cysteine, Trp = tryptophan, Pro = proline, His = histidine, Gln = glutamine, Arg = arginine, Ile = isoleucine, Met = methionine, Thr = threonine, Asn = asparagine, Lys = lysine, Val = valine, Ala = alanine, Asp = aspartic acid, Glu = glutamic acid, Gly = glycine.
Initiation of translation mRNA Charged tRNA (anticodon; amino acid) Ribosome What is responsible for matching the correct amino acid with the tRNA having the corresponding anticodon?
Mutation • A change in the order (sequence) of bases in DNA • Heritable
Mutagens damage DNA • Mutations may be caused by: • Spontaneous loss of bases due to random motion of molecules (heat) • Faulty DNA synthesis/repair • Chemical mutagens (e.g., cigarette smoke; nitrosamines) • Radiation (e.g., X-rays; UV) • Mobile genetic elements (transposons) • Viruses (e.g., HIV)
Mutation examples point mutation missense frameshift silent mutations nonsense mutations