Bio 15 - 1) Histidine, Glycine, Histidine, Leucine,...

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1) Histidine, Glycine, Histidine, Leucine, Tyrosine 2) Transcription starts at binding sites called promoters on the DNA template strand, as opposed to the coding strand. Sort of like a primer for DNA polymerase, the promoter is a nucleotide sequence that the RNA polymerase binds to, but does not actually replicate. Promoters are similar in bacteria, but each promoter can have a different effect on the separate kinds of polymerases. 3) The genetic code is redundant because multiple codons correspond to the same amino acid. For example, UCU, UCC, UCA, UCG, all cord for Serine. The alteration is in the last nucleotide for each, but makes no difference. The code is unambiguous despite this because each codon corresponds to an Amino Acid, 1 start, or 3 stop “nonsense” codons. 4) A tRNA (transfer RNA) molecule is composed of 3 loops and a free OH group on its 3’ side. Two of the loops attach to the ribosome during protein synthesis while the 3 rd contains an anticodon sequence which is complementary with the RNA sequence that the tRNA attaches to. The tRNA binds to an activating enzyme (aminoacyl-tRNA synthetase), which also has the specific corresponding amino acid attached. The AA binds to the tRNA, releasing water, and then matches its codon with the complementary one on the mRNA. In prokaryotes, the tRNA needs to have a chemically modified molecule called N-formylmethionine to attach to the small ribosomal complex. Initiation factors bring this to the mRNA where the anticodon lines up and the big subunit joins to the small. 5) These activating enzymes must therefore correspond to a specific tRNA molecule as well as amino acid. There are 20 activating enzymes for each AA, but some of these can possibly take several tRNAs. After the initiation complex is formed, the A (aminoacyl), P (polypeptide) and E (exit) sites are. At the P site, peptide bonds are created. At the A site, successive tRNAs with aminco acids will bind to continue the synthesis. These exit from the E site. It is important that the ribosomal complex bind to the beginning of the mRNA so that all of the transcribed gene can be translated. 6) Eukaryotes, which posses a nucleus, require that the mRNA be completely formed
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Bio 15 - 1) Histidine, Glycine, Histidine, Leucine,...

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