BIO 2133 Lecture Notes - Lecture 5: Polyadenylation, Methyl Group, Aminoacyl-Trna

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whitespider72

19 May 2016

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Document Summary

Translation in prokaryotes: the mrna gets translated in the 5"-3" direction(upstream). The mrna may have a non-coding region near the 5" and 3" ends. There is a shine-dolgarno sequence where the ribosome binds and another non-coding region and then there is the start codon aug. and that"s where translation begins until one of the stop codons is reached (uaa, uag, uga) Initiation: the ribosome recognizes the dolgarno sequence and binds to it then it moves to the right scanning the mrna until it hits the start codon aug at the p site. E stands for exit since trna exits from that site. In eukaryotes, the 5" end begins with a guanine nucleotide attached to a methyl group and the bond between that nucleotide and the next one is different one than normal. This 5" cap is the ribosome binding site.

Related Questions

Put the following list of events in the correct order following the steps required for eukaryotic gene expression: i. The ribosome shifts by one codon ii. A methionine-charged tRNA binds to the first AUG codon from the 5â end of the mRNA iii. An amino acid charged tRNA with the correct matching anticodon binds to the A-site iv. The amino acid from the tRNA in the P-site binds to the amino acid of the tRNA in the A-site v. The large ribosomal subunit binds vi. The small ribosomal subunit binds to a recognition sequence on the mRNA

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Facts about ribosomes

Indicate whether each of the following statements aboutribosomes is true or false.

1. Ribosomes are composed of tRNA and protein. TrueFalse
2. During translation in eukaryotes, some ribosomes remain free inthe cytoplasm while others attach to protein channels embedded inthe RER. TrueFalse
3. During initiation of translation, the small ribosomal subunitjoins to the mRNA and initiator rRNA, followed by the largeribosomal subunit. TrueFalse
4. When a ribosome first assembles on the mRNA, the initiator tRNAoccupies the A site while the P and E sites are empty.TrueFalse
5. During translation, a charged tRNA first binds to the ribosomeif its anticodon matches the codon in the E site. TrueFalse
6. A peptide bond forms between the amino acid attached to a tRNAin the A site and the growing polypeptide attached to a tRNA in theP site. TrueFalse
7. Uncharged tRNA molecules in the E site are ejected from theribosome. TrueFalse
8. No more than 2 tRNA molecules are bound to a ribosome at anygiven time. TrueFalse
9. During translocation of the ribosome, tRNA molecules move fromthe P site, to the A site, to the E site, and are then ejected fromthe ribosome. TrueFalse
10. During translation, an amino acid attached to a tRNA in the Asite is transferred to a growing polypeptide attached to a tRNA inthe P site. TrueFalse