Control of Gene Expression Quiz

A neuron and a white blood cell have very different functions. For example, a neuron can receive and respond to electrical signals while a white blood cell defends the body against infection. This is because ______.

• the proteins found in a neuron are completely different from the proteins found in a white blood cell.

• the neuron and the white blood cell within an individual have the same genome.

• the neuron expresses some mRNAs that the white blood cell does not.

• neurons and white blood cells are differentiated cells and thus no longer need to transcribe and translate genes.

The distinct characteristics of different cell types in a multicellular organism result mainly from the differential regulation of the _________________.

• replication of specific genes.

• transcription of genes transcribed by RNA polymerase II.

• transcription of housekeeping genes.

• proteins that directly bind the TATA box of eukaryotic genes.

The human genome encodes about 21,000 protein-coding genes. Approximately how many such genes does the typical differentiated human cell express at any one time?

• 21,000—all of them

• between 18,900 and 21,000—at least 90% of the genes

• between 5000 and 15,000

• less than 2100

Which of the following is not a good example of a housekeeping protein?

• DNA repair enzymes

• histones

• ATP synthase

• hemoglobin

Which of the following statements about differentiated cells is true?

• Cells of distinct types express nonoverlapping sets of transcription factors.

• Once a cell has differentiated, it can no longer change its gene expression.

• Once a cell has differentiated, it will no longer need to transcribe RNA.

• Some of the proteins found in differentiated cells are found in all cells of a multicellular organism.

Investigators performed nuclear transplant experiments to determine whether DNA is altered irreversibly during development. Which of the following statements about these experiments is true?

• Because the donor nucleus is taken from an adult animal, the chromosomes from the nucleus must undergo recombination with the DNA in the egg for successful development to occur.

• The embryo that develops from the nuclear transplant experiment is genetically identical to the donor of the nucleus.

• The meiotic spindle of the egg must interact with the chromosomes of the injected nuclei for successful nuclear transplantation to occur.

• Although nuclear transplantation has been successful in producing embryos in some mammals with the use of foster mothers, evidence of DNA alterations during differentiation has not been obtained for plants.

In principle, a eukaryotic cell can regulate gene expression at any step in the pathway from DNA to the active protein. Place the types of control listed below at the appropriate places on the diagram in Figure Q8-7.

In principle, a eukaryotic cell can regulate gene expression at any step in the pathway from DNA to the active protein. Place the types of control listed below at the appropriate places on the diagram in Figure Q8-7.

• translation control

• transcriptional control

• RNA processing control

• protein activity control

Fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. The genes of a bacterial __________________ are transcribed into a single mRNA.

Which of the following statements about transcriptional regulators is false?

• Transcriptional regulators usually interact with the sugar–phosphate backbone on the outside of the double helix to determine where to bind on the DNA helix.

• Transcriptional regulators will form hydrogen bonds, ionic bonds, and hydrophobic interactions with DNA.

• The DNA-binding motifs of transcriptional regulators usually bind in the major groove of the DNA helix.

• The binding of transcriptional regulators generally does not disrupt the hydrogen bonds that hold the double helix together.