Given the following mutants and conditions, predict the expression of the of the lacZ gene (no expression, basal level of expression, or activated level of expression). A mutant of E. coli that has a mutation in the operator of the lac operon that prevents the repressor from binding

Glucose	Lactose	Expression
+	-	1
+	+	2
-	-	3
-	+	4

#Question id: 4078

#Unit 3. Fundamental Processes

Which of the following is (are) required for splicing to occur?

a. two transesterification reactions

b. intact, naturally occurring introns

c. formation of a lariat like structure

d. a branch-point G residue

#Question id: 4079

#Unit 3. Fundamental Processes

What is the evidence that pre-mRNAs are not synthesized unless machinery for processing is properly positioned?

#Question id: 4080

#Unit 3. Fundamental Processes

How the location of exons and introns within a gene are determined?

#Question id: 4081

#Unit 3. Fundamental Processes

Which of the following regulatory scenarios of cell-type-specific expression of fibronectin isoforms in humans is (are) consistent with information on known splicing factors?

a. A Tra-like splicing factor expressed in fibroblasts is required for inclusion of EIIIA and EIIIB exons.

b. An Sxl-like splicing factor is required in hepatocytes for exclusion of EIIIA and EIIIB exons.

c. A Tra-2-like factor enhances binding of the cleavage/polyadenylation complex in fibroblasts.

d. A Dsx-like protein is required to inhibit transcription of the fibronectin gene.

#Question id: 4082

#Unit 3. Fundamental Processes

Which of the following is (are) not involved in alternative splicing in eukaryotes?

#Question id: 4083

#Unit 3. Fundamental Processes

Differential splicing of the Ca2+-activated K+ channel gene in ciliated neurons results in

a. hair cells with different response frequencies.

b. different channel isoforms.

c. channels that open at different calcium concentrations.

d. different channel mRNAs expressed in different cells.