Biology 1002B Lecture Notes - Lecture 8: Polyadenylation, Precursor Mrna, Spliceosome

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indigotortoise482

3 Feb 2020

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Protein-coding gene is terminated differently from a prok. Gene: the euk gene has no terminator sequence in the dna that signals rna pol to stop transcribing. 12. 4 translation: mrna-directed polypeptide synthesis: translation is the assembly of amino acids into polypeptides on ribosomes, occurs in the cytoplasm of eukaryotes. Fig 12. 12 aminoacylation or charging (right: ribosomes are ribonucleoprotein particles that carry out protein synthesis by translating mrna into chains of amino acids. Fig 12. 15 translation elongation (far right: elongation cycle is pretty similar in prokaryotes and eukaryotes, besides the rate at which it occurs . In eukaryotes the coordinated synthesis of proteins with related functions occurs but without the need to organize genes under the control of a single promoter in an operon. Short term regulation involves regulatory events in which gene sets are quickly turned on or off in response to changes in environmental or physiological conditions in the cell"s/organisms environment: most similar to prokaryotic gene regulation.

Related Questions

1. Pre-messenger RNA processing

a. What are the major steps of pre-mRNA processing?

b. How is a cap added to the 5â-end of mRNAs? What is that cap? Can you explain some functions of the cap?

c. What processing happens at the 3â-end of eukaryotic mRNAs? What enzyme is responsible for this? Can you explain some functions of this processing?

d. What is RNA editing? Are you prepared to identify how a single site of editing could change the expression of an mRNA?

e. What are the catalytic sites within an intron? How are they recognized by the spliceosome (you do not have to memorize exact interactions, just understand generally how this occurs)?

f. What is the mechanism of catalysis carried out by the spliceosome? How is this similar to Group I and Group II introns?

g. Are you prepared to answer questions about how splicing defects may result in non-functional protein products?

h. What is alternative splicing and how can it increase the size of the proteome?

emeraldcrocodile431

Match the following:

1	Region which lies upstream of thetranslation start site contains the Shine Dalgarno sequence
2	Sequence added to the 3' end of thepre-mRNA which affects mRNA stability
3	Establishes the reading frame andspecifies the first amino acid of the protein chain
4	DNA sequence that the transcriptionapparatus recognizes and binds to initiate transcription
5	Expressed sequences of DNA that arenot removed during alternative splicing
6	Signals the end of translation andthe protein molecule
7	Group of three nucleotides that codefor an amino acid
8	Site begins the coding region of thegene and is located 25-30 nucleotides downstream of the TATAbox
9	Non-coding sequences of DNA thatintervene within coding regions of a gene
	10 Ribosome binding site ineukaryotes; functions in the initiation of translation and mRNAstability
11	A sequence which lies downstream ofthe coding region of the gene; determines the location of the 3'cleavage site in the pre-mRNA molecule
12	Sequence of nucleotides at the 3' endof the mRNA that is not translated into protein; affects thetranslation and stability of the mRNA molecule

A.	5' untranslated region
B.	AAUAAA consensus sequence
C.	Promoter
D.	Transcription start site
E.	3' untranslated region
F.	Introns
G.	Initiation codon (AUG)
H.	Poly(A) tail
I.	5' cap
J.	Termination codon (UAA, UGA, UAG)
K.	Exons
L.	Sense codon

ivorymacaw91

QUESTION 1

Which of the following statements regarding splicing is FALSE?

A) The length of introns determines the efficiency of splicing.

B) Many human neurological disorders are caused by splicing errors and/or mutations in splicing factors.

C) Splicing requires the action of a variety of snRNAs that direct the transesterification reactions.

D) Splicing is dictated by sequence features in pre-mRNA transcripts

QUESTION 2

Which of the following mRNA processing factors does NOT associate with the CTD of RNA polymerase II?

A) splicing factors

B) polyadenylation factors

C) miRNAs/siRNAs

D) capping proteins

QUESTION 3

Which of the following statements about mRNA stability is FALSE?

A) Deadenylation-independent mRNA decay is exclusively in the 5' to 3' direction.

B) The most common pathway of mRNA decay is deadenylation-dependent.

C) Yeast mRNA decay occurs primarily in the 5' to 3' direction, while 3' to 5' decay is more common in mammalian cells.

D) Decapping enzymes are required for all pathways of mRNA decay.

QUESTION 4

You obtain the sequence of a gene containing 10 exons, 9 introns, and a 3â² UTR containing a polyadenylation consensus sequence. The fifth exon also contains a polyadenylation site. To test whether both polyadenylation sites are used, you isolate mRNA and find a longer transcript from muscle tissue and a shorter transcript from all other tissues. Which of the following is the most likely mechanism underlying these alternative transcripts?

A) The fifth exon is spliced out of the mature mRNA transcript in muscle cells.

B) Muscle cells have less effective polyadenylation than other tissues.

C) An alternative CPSF protein is expressed in muscle cells with lower affinity for the polyadenylation sequence in exon 5.

D) The mRNA in muscle cells is edited to eliminate the polyadenylation sequence in exon 5.

blushdonkey474

Biology 1002B Lecture Notes - Lecture 8: Polyadenylation, Precursor Mrna, Spliceosome

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