BIOS 1700 Lecture Notes - Lecture 8: Peptide Bond, Release Factor, Operon

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silvergerbil790

13 Sep 2016

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Last step in the central dogma of molecular biology. 20 of these enemies exist: a charged or activated trna is one that is fully connected to its amino acid. The ribosomes are composed of: large subunit. Exit site: where uncharged trna leaves the ribosome. Peptidyl site: where amino acids are bonded together. Aminoacyl site: where amino acid attached to trna enters ribosome: small subunit. Wednesday, september 7, 2016: a codon sequence is needed. There are 64 codons that code for 20 amino acids: aug is the start codon. Translation begins at this codon only: codons are found in mrna, anticodons, found in trna, are anti-parrallel and complementary to the codons in mrna. Always, always, write the anticodon sequence in the 5" to 3" direction! Which codon is the right one: all depends on the reading frame. Reading frame: where the reading of each base begins.

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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

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Facts about ribosomes

carmineraccoon103

3. Describe the aminoacylation of a tRNA reaction being careful to include information about how one particular amino acid is attached to a particular tRNA.

4. All of the following steps are part of the process of gene expression in eukaryotes. Number them toreflect the approximate order in which each occurs during this process.
a) Introns are removed from the original transcript of the gene.

b) A 5â cap is added onto the mRNA.

c) A specific aminoacyl-tRNA synthetase charges Val-tRNA.

d) Val-tRNA enters the A site of the ribosome.

e) The mRNA is cleaved near the poly(A) site in its 3â UTR.

f) A translation release factor binds to the stop codon.

g) RNA polymerase II initiates mRNA synthesis

h) The mRNA is transported out of the nucleus into the cytoplasm.

i) An activator protein binds to an enhancer.

BIOS 1700 Lecture Notes - Lecture 8: Peptide Bond, Release Factor, Operon

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