Pre-Test

Chapter 19: Eukaryotic Genomes: Organization, Regulation, and Evolution

Pre-Test

1 .

Histones are _____. (Concept 19.1

master genes that affect development

groups of genes that respond to environmental changes

proteins around which DNA is coiled

portions of genes that are transcribed

portions of genes that are eliminated by DNA splicing

2 .

Your muscle and skin cells are different because _____. (Concept 19.2

) [Hint]

they contain different sets of genes

they contain different chromosome sets

they contain different operons

different genes are switched on and off in each type of cell

they contain different histones

3 .

DNA methylation is a mechanism used by eukaryotes to _____. (Concept 19.2

) [Hint]

inactivate genes

increase the rate of transcription

terminate transcription

facilitate the binding of DNA to intermediate filaments

cause apoptosis

4 .

In humans, the hormone testosterone enters cells and binds to specific proteins, which in turn bind to specific sites on the cells' DNA. These proteins probably act to _____. (Concept 19.2

) [Hint]

help RNA polymerase transcribe certain genes

alter the pattern of DNA splicing

promote recombination

unwind the DNA so that its genes can be transcribed

cause mutations in the DNA

5 .

It is possible for a cell to make proteins that last for months; hemoglobin in red blood cells is a good example. However, many proteins are not this long-lasting; they may be degraded in days, hours, or even minutes. What is the advantage of short-lived proteins? (Concept 19.2

) [Hint]

Most proteins are used only once.

Most cells have a short life span.

Cells lack the raw materials to make most of the proteins they need.

Long-lasting proteins are likely to make the cell cancerous.

Short-lived proteins enable the cells to control their activities precisely and efficiently.

6 .

Which of the following would be most likely to lead to cancer? (Concept 19.3

) [Hint]

amplification of a proto-oncogene and inactivation of a tumor-suppressor gene

hyperactivity of a proto-oncogene and activation of a tumor-suppressor gene

failure of a proto-oncogene to produce a protein and amplification of a tumor-suppressor gene

failure of both a proto-oncogene and a tumor-suppressor gene to produce proteins

hyperactivity of both a proto-oncogene and a tumor-suppressor gene

7 .

In normal cells, the genes that malfunction in cancer usually _____. (Concept 19.3

) [Hint]

control RNA transcription

are responsible for sex determination

code for enzymes involved in cellular respiration

are not present

regulate cell division

8 .

All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs? (Concept 19.3

) [Hint]

Proto-oncogenes protect cells from infection by cancer-causing viruses.

Proto-oncogenes are genetic junk that has not yet been eliminated by natural selection.

Proto-oncogenes are unavoidable environmental carcinogens.

Cells produce proto-oncogenes as a by-product of mitosis.

Proto-oncogenes are necessary for the normal control of cell growth and division.

9 .

Retrotransposons differ from other transposons in that _____. (Concept 19.4

) [Hint]

retrotransposons have lost the ability to move about a genome

retrotransposons are likely to be the remains of a viral infection

retrotransposons have retained the ability to move about a genome, an ability that has been lost by other transposons

retrotransposons move via an RNA transcript, whereas other transposons do not

only retrotransposons can affect gene expression

10 .

Gene duplication has played a critical role in evolution because it _____. (Concept 19.5

) [Hint]

produces redundant copies of existing genes, which are then free to mutate and adopt new functions

increases the number of pseudogenes in the genome

increases the likelihood of viral infection in cells

increases the amount of DNA in the genome

almost always introduces immediate benefits for the organism