MBB 222 Final: Final Exam Main Topics Part 1

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browncricket987

20 Dec 2018

School

Simon Fraser University

Department

Molec Biol & Biochem

Course

MBB 222

Professor

Adam Barlev

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Document Summary

The two steps of the aminoacyl-trna synthetase charging reaction: both the amino acid and atp are bound to the enzyme. An aminoacyl- adenylate intermediate is then formed between the carboxyl group of the amino acid and the phosphate of atp. Hydrolysis of the released ppi makes the overall reaction irreversible: cleavage of the phosphodiester bond facilitates the formation of aminoacyl trna as the amino acid is transferred to the 2 -hydroxyl or 3 -hydroxyl of the trna acceptor stem. The molecular adaptor required for protein synthesis is trna. Crick proposed that the existence of an adaptor molecule implied the need for an enzyme to catalyze the attachment of an amino acid to this molecule. The synthesis of an aminoacylated, or charged, trna is coupled with the hydrolysis of. The anticodons of the trnas in the a and p sites are base paired to the codons of the mrna.

Related Questions

The energy for protein synthesis comes from which of the following?

	a.	The ATP used in the synthesis of aminoacyl-AMP molecules that are then converted to aminoacyl-tRNAs
	b.	The GTP that is bound to initiation factors used in the initiation and translocation phases of translation
	c.	The high energy C-N bond of the amino acid
	d.	a, b, and c
	e.	a and b

The enzymatic process of "charging" a molecule of tRNA is similar to other enzyme catalyzed reactions. Which of the following correctly describes such similarities?

	a.	Formation of an acyl-adenylate intermediate coupled to the hydrolysis of pyrophosphate in fatty acid activation is similar to reactions involved in the "charging" of tRNA.
	b.	Proofreading and correcting abilities that prevent incorporation of the wrong molecule are analogous to the action of DNA polymerase.
	c.	The aminoacyl-tRNA synthetase is a relatively non-specific enzyme (i.e., it can activate many different amino acids) and, in this respect, is similar to ribonucleotide reductase.
	d.	a and b.
	e.	b and c.

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.

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MBB 222 Final: Final Exam Main Topics Part 1

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