AQA A-Level Biology 3.8 The control of gene expression quiz

degenerate

non-overlapping

universal

made of triplets

It removes a whole gene from the chromosome along with the single base

It causes a frameshift, so every triplet after the deletion is read differently

It always creates a premature stop codon right at the very start of the whole gene

It permanently changes the DNA in the gene into a strand of RNA

totipotent

multipotent

pluripotent

unipotent

It binds to a receptor on the cell-surface membrane and triggers a second messenger inside the cell, which then activates the enzymes that carry out transcription of the gene

It is transcribed directly into a strand of mRNA that is then translated

It methylates the DNA of the target gene so that transcription is switched on

It diffuses into the cell, binds a receptor on a transcription factor changing its shape, and the complex enters the nucleus and stimulates RNA polymerase

binding to a complementary mRNA and causing its breakdown or blocking its translation

adding methyl groups directly to the DNA of the target gene to silence it permanently

cutting the target gene out of the chromosome so it can never be transcribed

increasing the acetylation of the histone proteins around which the DNA is wound

increased DNA methylation and increased histone acetylation

increased DNA methylation and decreased histone acetylation

decreased DNA methylation and increased histone acetylation

decreased DNA methylation and decreased histone acetylation

Both an oncogene and a tumour suppressor gene are completely switched off in the cancer cell

An oncogene is inactivated and completely switched off, while a tumour suppressor gene becomes permanently over-active

An oncogene is over-active (increased expression); a tumour suppressor gene is inactivated (decreased expression)

Both an oncogene and a tumour suppressor gene act to increase the rate of apoptosis

directly mutates the DNA of breast cells, acting as a powerful mutagen on the tissue

methylates all of the tumour suppressor genes within the breast cells at once

blocks the action of the immune system so abnormal cells are not destroyed

stimulates the division of breast cells, including already abnormal cells

It uses mRNA as a template to make complementary DNA (cDNA), which lacks introns

It cuts the DNA at specific recognition sequences, as a restriction enzyme does

It joins the isolated gene into a plasmid vector ready for insertion into a cell

It separates the different DNA fragments from one another according to their size

The hydrogen bonds between the two strands break and the strands fully separate

Primers bind to the start of each target strand by complementary base pairing

Taq polymerase builds new complementary strands extending out from the primers

The double helix twists up tightly on itself and becomes supercoiled

binds indiscriminately to absolutely any piece of DNA that it happens to come into contact with anywhere at all in the whole sample

cuts the DNA precisely at the position of the allele it is searching for

is single-stranded and has a base sequence complementary to the target, so it hybridises only where the target is present

changes the colour of the whole sample once it has been added to it

DNA sequencing that reads out every single base along the whole length of each fragment

centrifugation that separates the fragments according to their differing densities

the polymerase chain reaction used entirely on its own to sort the fragments

gel electrophoresis, where smaller fragments move further toward the positive electrode