CELL201 Lecture 4: Gene expression II

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skycaribou653

1 Feb 2018

School

University of Alberta

Department

Cell Biology

Course

CELL201

Professor

Paul Lapointe

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Document Summary

Gene expression ii: most mrnas in eukaryotes are monocistronic, they encode one polypeptide. In bacteria and archaea some are polycistronic, they encode several polypeptides. One polypeptide is required for the other to work: polycistronic transcription units are called operons. Translation rrna + protein ribosomes: ribosomes are found free in the cytoplasm, bound to er and other nuclear envelop. There are 20 types: synthetases also proof read that the aminoacyl is correct. They have binding sites for the 3" end of the trna and amino acid: translation: starts from n terminal (5") and grows till c terminal (3", mrna is read in 5" to 3" direction. After the base pair is formed, large ribosomal unit joins the complex facilitated by gtp eifs with gtp bind to initiation trna(met) and then to small ribosomal unit. The resulting complex binds to the 5" end of the mrna, recognising the 5" cap.

Related Questions

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

carmineraccoon103

Gene ExpressionQuestions

Question 1

#1) Match the following reactions to the correct step of proteinsynthesis by ribosomes.

___ Hydrolysis of GTP and disassembly of the translationcomplex.

___ binding of initiator aminoacyl-tRNA

___ formation of the peptide bond

___ translocation of ribosome

___ Use of 2 mole-equivalents of ATP and attachment of an aminoacid to a transfer RNA molecule

Answer Choices for Number #1
A. initiation step
B. elongation step
C. termination step
D. aminoacyl-tRNA synthetase reaction

Question 2

#2) Mark which of the following are needed for the synthesis ofRNA by RNA polymerase:

___ primer

___ ATP, CTP, GTP, UTP

___ dATP, dCTP, dGTP, dTTP

___ template

Question 3

#3) Mark which of the following are properties of a bacteria(prokaryotic) messenger RNA:

___		It has a cap at the 5'-end.
___		It has a poly-A tail at the 3'-end.
___		It has a 5'-untranslated region (UTR).
___		It has a 3'-untranslated (UTR) region.

Question 4

#4) Match the following RNA molecules to their respectivefunctions in the cell.

___ transfer RNA

___ ribosomal RNA

___ messenger RNA

___ small nuclear RNA (snRNA)

Answer Choices for Number #4

A. This RNA serves as the template for protein synthesis.
B. This molecule is a molecular component of ribosomes.
C. This molecule is a component of spliceosomes and serves torecognize the exon-intron junctions
D. This RNA molecule is delivers the amino acid to the ribosome andit recognizes the appropriate codons with its anticodon loop.

burgundyturtle416

CELL201 Lecture 4: Gene expression II

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