QUESTION 1 Choose the one correct answer The presence of lac

QUESTION 1

(Choose the one correct answer) The presence of lactose.....

inhibits the lac operon.

is necessary to activate the lac operon.

activates the transcription of lacZ, but inhibits transcription of lacY and lacA

activates the transcription of lacY and lacA, but inhibits transcription of lacZ

10 points   

QUESTION 2

Transcription in bacteria is controlled without promoter regions.

True

False

10 points   

QUESTION 3

Which of the following statements is TRUE regarding enhancers? (Choose the one correct answer)

Enhancers are regions of DNA which are always located within the promoter and help inhibit transcription.

Enhancers are protein activators that bind to the promoter region of DNA

Enhancers are regions of DNA that may located near or far from the transcription initiation start site that are bound by activator proteins to help activate transcription.

Enhancers are regions of DNA which are always located within the promoter and help activate transcription.

10 points   

QUESTION 4

The 5\' Cap that is placed on mRNA in eukaryotes plays what role(s)? Choose ALL that apply.

Aids in export of mRNA out of nucleus.

Stabilizes mRNA.

Aids in Ribosomal (translational machinery) recognition of mRNA.

aids in mRNA splicing.

10 points   

QUESTION 5

The RNA component and not the proteins, of the RNA splicing machinery is responsible for splicing mRNA.

True

False

10 points   

QUESTION 6

Which of the following is FALSE regarding Alternative Splicing? (Choose ALL that apply)

Alternative splicing occurs at extremely high levels in nervous tissue.

Alternative splicing alternates involves the inclusion of different exons within a given gene.

Alternative splicing involves the inclusion of different introns within a given gene.

Alternative splicing allow for multiple mRNA transcripts to be expressed from one gene

10 points   

QUESTION 7

Which of the following is FALSE regarding Dissociator? (Choose the one correct answer.)

Movement of Dissociator only occurs during early development.

It is a transposable genetic element.

It \'s presence within a color gene disrupts pigment production.

It\'s movement is controlled by a second element called \'Activator\'.

10 points   

QUESTION 8

An antigen can be a protein, nucleic acid, or a polysaccharide.

True

False

10 points   

QUESTION 9

Which of the following statements is TRUE regarding the cell cycle? Choose ALL that APPLY.

CDKs are downregulated by cyclins.

Mature, differentiated cells exit the cell cycle into a resting phase called G0.

DNA damage that occurs after the Restriction Point will not arrest the cell cycle since the cell has passed the \'point of no return\'.

CDKs are activated by CKIs

10 points   

QUESTION 10

Homeotic genes display spacial colinearity.

True

False

	A.	inhibits the lac operon.
	B.	is necessary to activate the lac operon.
	C.	activates the transcription of lacZ, but inhibits transcription of lacY and lacA
	D.	activates the transcription of lacY and lacA, but inhibits transcription of lacZ

Solution

Please find the answers below and reasons in parentheses:

Answer 1: Choice B (The lac operon is an inducible operon where presence of the substrate or lactose is associated with its binding to repressor protein and prevents the binding of repressor to the operator. As the operator cannot bind and block the operator, RNA polymerase can easily transit over linear gene of lac operon and promote transcription and translation. Presence of lactose is thus necessary for activation of lac operon)

Answer 2: False (Both prokaryotic and eukaryotic gene expression or transcription is modulated by presence of consensus and highly conserved pre-operon sequences called the promoters. The location, consensus and accuracy of these promoter regions before/upstream the gene determines the rate and extent of gene expression. Because prokaryotic promoters are ubiquitous in nature, they are often used for recombinant DNA technology purpose in artificially synthesized genes. )

Answer 3:Choice C (Theoratically, enhancers are stretches of DNA in the consensus sequence of a gene and may spread from the promoter to the end of the gene. They can also be found anywhere upstream or downstream the gene. Functionally, they are actively engaged in promoting binding of proteins which enahnce the rate and efficiency of transcription and translation. They are found in both porkaryotes and eukaryotes.)

Answer 4: All statements are correct (the 5\' capping of nascent mRNA is highly important event for transit of mRNA from nucleus to cytoplasm, prevention of degradation by endonucleasea, stabilization of mRNA and idenfication by ribosome for translation. This event is important because eukaryotic cells are compartementalized in nature and due to different nature of each compartment, the physical nature of RNA needs to be saved. Thus, 5\' capping is necessary for this purpose and maintain fidelity of translation.)