BIOLOGY 1P03 Lecture Notes - Ribosome, Methionine, Ribosomal Rna

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erinhound718

28 Mar 2013

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Initiation: translation begins when trna and rna bind to a ribosome. The first amino acid in all proteins is a methionine (aug codon) An initiation complex a small ribosomal subunit, a methionine trna, and a methionine amino acid binds to an aug codon in an mrna molecule. A large subunit of the ribosome joins the complex to complete the assembly of the ribosome. The methionine trna binds to the first binding site on the large ribosome subunit. Elongation: amino acids are added one at a time to the growing protein chain. Assembled ribosomes have two binding sites and a catalytic site. The first binding site has methionine and its rrna attached. The second biding site accepts another trna with an anticodon complementary to the codon on the mrna associated with the second biding site. The catalytic site forms peptide bond between the two amino acids.

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

periwinklemuskrat632

Facts about ribosomes

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BIOLOGY 1P03 Lecture Notes - Ribosome, Methionine, Ribosomal Rna

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