Optimisation of a PCR reaction is often a compromise between the competing demands for precision, efficiency and yield. Although the specific effects may vary, generally, increasing the annealing temperature will increase non-specific primer binding and reduce precision. Increasing the length of the elongation phase will reduce the proportion of incomplete newly-synthesised strands and therefore increase yield. In this case, the potential effect on efficiency is unclear. Increasing the elongation phase would increase the reaction time, but the time taken to ramp down to a lower annealing temperature would be reduced.

Which of the following techniques doesn’t involve use of a secondary antibody?

#Question id: 4066

#Unit 3. Fundamental Processes

Specific DNA control elements in promoters can

a. interact with general transcription factors.

b. interact with repressor proteins. 

c. interact with activator proteins.

d. remain unavailable because of condensed chromatin.

#Question id: 4067

#Unit 3. Fundamental Processes

Reporter genes are used to

a. express enzymes that are not easily assayed in cell extracts.

b. express enzymes that are easily assayed in cell extracts.

c. characterize DNA control elements. 

d. characterize reporter plasmids.

#Question id: 4068

#Unit 3. Fundamental Processes

The three eukaryotic RNA polymerases can be distinguished by

a. the types of genes they transcribe.

b. the number and types of large subunits.

c. their differential sensitivities to cycloheximide.

d. their differential sensitivities to α-amanitin.

#Question id: 4069

#Unit 3. Fundamental Processes

Which of the following can be identified using a series of promoter linker scanning mutations?

a. areas of the promoter that are non-essential

b. areas of the promoter that are essential

c. the presence of separate transcriptional control regions

d. spacing constraints on separate transcriptional control regions

#Question id: 4070

#Unit 3. Fundamental Processes

An enhancer

a. can be located upstream of a promoter.

b. can be located downstream of a promoter.

c. can be located a variable distance from the promoter.

d. is always located within 1 kb of the promoter.

e. can be cell-type-specific.

#Question id: 4071

#Unit 3. Fundamental Processes

The fact that a specific protein leaves a “footprint” on a DNA molecule is indicative of

a. a lack of interaction between the specific protein and DNA.

b. protection from DNAse by the specific protein.

c. binding of the specific protein to all types of DNA.

d. binding of the specific protein to a specific sequence of DNA.