BIOSC 0160 Lecture Notes - Lecture 8: Release Factor, Methionine, Hiv-1 Protease

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taupesnake441

25 Oct 2017

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Lecture 8: translation: mrna has left nucleus and is now in the cytoplasm, as soon as that mrna is transcribed ribsomes will bind to it and begin translation. Ribosomes: ribosomes in eukaryotes are larger than ribosomes in prokaryotes, 80s subunits in eukaryotes, 70s subunits in prokaryotes, small subunit holds mrna in place, large subunit is where peptide bond forms. Initiation: the small subunit binds to another complementary sequence, not the start codon. The first aug it encounters in a protein will be the first methionine. Moves 5" 3": the met charged trna binds to the mrna and the large unit comes in and binds. In prokaryotes, the first thing that gets translated is the shine dalgarno sequence (5"aggagg3"). Upstream of the start codon, downstream of the +1. In eukaryotes, small subunit binds to the 5" cap of the mrna: the first amino acid will be in the p site when the complex first comes together.

Related Questions

Gene expression is a multi-step process. Place these events in the correct order.

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charged tRNA molecules read the next codon, entering the A site of the ribosome.

Translocation of the mRNA to the cytoplasm.

Recruitment of RNA polymerase.

tRNA(Met) binds to the start codon AUG in the P site of the ribosome.

Assembly of small and large ribosome subunits on the mRNA.

Processing of the primary RNA molecule.

Release factors recognize the stop codon, signaling the release of the protein, mRNA and ribosome subunits.

Synthesis of primary RNA molecule, a direct copy of the DNA template.

Recognition of the mRNA by the small ribosome subunit .

Peptidyl transferase, transfers the amino acid of the incoming tRNA to the growing peptide chain.

Binding of transcription factors to the promoter.

blacklion206

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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BIOSC 0160 Lecture Notes - Lecture 8: Release Factor, Methionine, Hiv-1 Protease

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