Biology 1002B Lecture 14: Lecture 14-introns

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viridiancricket542

23 Aug 2017

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Introns: non-protein coding sequences that interrupt the protein-coding sequence. Introns are transcribed into pre-mrna but are removed in the nucleus. Splicesme cleaves pre-mrna to release intron and join exons. This explains why the # of genes are much less than the # of proteins produced: exon shuffling: intron-exon junctions fall where dividing major functional regions in encoded proteins. Transcription and translation are separated by nuclear envelope. No terminator sequence in the dna that signals rna polymerase to stop transcribing. Proteins bind to polyadenylation signal (repeated a bases (cid:374)ear (cid:1007)" ge(cid:374)e that is tra(cid:374)s(cid:272)ri(cid:271)ed(cid:895) i(cid:374) the. Many may not contain introns (could be larger than exons) Translation can start on mrna that is being transcribed. Promoter proximal region (contains regulatory sequences) enhancer. [regulatory that controls the rate of transcription of the gene which produces a pre- (cid:373)rna (cid:894)with (cid:1009)" (cid:272)ap a(cid:374)d (cid:1007)" poly(cid:894)a(cid:895); processing pre-mrna involves removing introns to make functional mrna)] 4: rna polymerase ii cannot recognize the promoter sequence.

Related Questions

please answer all the questions answering only one question is not helpful!
Question 1

0 / 1 pts

Which of the following E. coli strains with the lac genotypes will synthesize beta-galactosidase in the presence of lactose?

Note: Superscript wouldn't work in the answers, so for example, lacIs means lacI^s(superrepressor of lacI)

lacIâ lacPâ lacOâ lacZâ lacYâ

lacIs lacP+ lacO+ lacZ+ lacYâ / lacI+ lacP+ lacO+ lacZâ lacY+

lacIs lacPâ lacO+ lacZâ lacY+ / lacI+ lacP+ lacO+ lacZ+ lacY+

lacIâ lacPâ lacO+ lacZ+ lacY+

lacI+ lacP+ lacO+ lacZ+ lacY+

Question 2

0 / 1 pts

Some mutations in the trp 5' UTR region increase termination by the attenuator. An example of a mutation that may have this effect is a

Choose the best answer!

mutation that changes the bases in region 3 of the 5' UTR, such that they no longer pair with region 2 or 4.

deletion of the two tryptophan codons in the 5' UTR leader peptide.

deletion in region 2 in the 5' UTR that prevents it from pairing with region 3.

The second and third answers are correct.

The first, second, and third answers are correct.

IncorrectQuestion 3

0 / 1 pts

Several examples of antisense RNA regulating translation in bacterial cells have been discovered. If you wanted to design a construct to artificially control translation of a bacterial gene with antisense RNA, what type of sequences should the antisense RNA contain?

A sequence complementary to the operator of an operon.

A sequence complementary to a 5' UTR.

A sequence complementary to the Shine-Dalgarno site of the mRNA.

The first and second choices are correct.

The second and third choices are correct.

Question 4

0 / 1 pts

Which of the following correctly describes the function of microRNAs?

Choose the best answer.

MicroRNAs are encoded by genes in the genome of an organism.

MicroRNAs form mRNA which encodes a protein repressor for another gene.

MicroRNAs encode a mRNA that base pairs with itself, forming double stranded RNA.

MicroRNAs are cut into small pieces, then bound by the complex of proteins called RISC to repress the translation of other mRNAs in the cell.

The first and second answers are correct.

The first, third, and fourth answers are correct.

The third and fourth answers are correct.

whitemole409

A. Provide the function for the following enzymes.

Topoisomerase

Helicase

Primase

DNA Polymerase I

DNA Polymerase III

Ligase

B. The study of changes in gene expression that occurs without alteration to genes is called

_________.

C. Noncoding regions in eukaryotic DNA are called ________. These have _______ functions

and alter gene expression.

D. Shift pairing of RNA at the third position is called ____________.

E. An operon is composed of _____.

F. In the Lac operon, if lactose is present, the operator of the lac operon is switched ____;

therefore, this is an example of a(n) ______ operon.

G. Name the 4 methods of horizontal gene transmission and how each occurs.

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

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Biology 1002B Lecture 14: Lecture 14-introns

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