bio chap 19

Question 1

True or false: It is likely that over half of human proteins have their synthesis regulated by miRNAs.

Answer 1

true

Question 2

True or false: The nucleosome is a complex of eight histone subunits wrapped by a short DNA strand approximately 10 base pairs long.

Answer 2

false

Question 3

True or false: The miRNA-RISC-mRNA complex enhances the translation efficiency of the mRNA transcript.

Answer 3

false

Question 4

True or false: Histone modification occurs only during early development.

Answer 4

false

Question 5

Analysis of the primary transcript for an insulin receptor protein reveals that exon 11 has been removed from the mRNA in skeletal muscle, but not in liver. How does this affect the proteins synthesized in these two types of cells?

Answer 5

The insulin receptor in skeletal muscle has a higher affinity for insulin than the receptor in the liver

Question 6

Which of the following is not an accurate description of events leading to the lysogenic pathway following viral infection in a bacterium?

Answer 6

Reduction in the concentration of cI protein is the most important contributor to lysogeny

Question 7

True or false: RNA splicing joins together the coding regions of messenger RNA in their original linear order after the removal of introns.

Answer 7

true

Question 8

Which one of the following is not a result of RNA editing?

Answer 8

the recruitment of RNA polymerase following the binding of general transcription factors

Question 9

Which of the following statements about protein modifications is incorrect?

Answer 9

Proteins can be modified following the addition of a polyadenylated tail

Question 10

True or false: Amino acid sequences that are rich in lysine and protrude from the histone proteins in the nucleosome are called “tails”.

Answer 10

true

Question 11

A virus that infects bacteria is called a ___________

Answer 11

bacteriophage

Question 12

In female humans and other mammals, dosage compensation is achieved by the inactivation of one of the two X chromosomes in each cell. Which one of the following does not occur in the X-inactivation mechanism of female mammals?

Answer 12

Xist RNA is attracted to and associates with a protein called the X-chromosome inactivation center (XIC), which becomes entirely coated with Xist.

Question 13

True or false: The primary transcript is transported directly to the cytoplasm and prepared for translation.

Answer 13

false

Question 14

True or false: Small interfering RNAs (siRNAs) are a type of small regulatory RNA that, like microRNAs, are incorporated into the RISC complex.

Answer 14

true

Question 15

Which one of the following is not a characteristic shared by miRNA and mRNA?

Answer 15

They both fold upon themselves, forming stems and hairpin loops that are stabilized by hydrogen bonding.

Question 16

Which one of the following statements about regulation of translation is incorrect?

Answer 16

Regulation of translation does not depend on sequences in the 3’UTR or the poly(A) tail.

Question 17

Which one of the following statements about gene regulation is incorrect?

Answer 17

gene regulation occurs only in prokartyotes

Question 18

The alternative pathways for viral infection—lytic and lysogenic—are determined by positive and negative regulatory effects of proteins produced by the virus following infection.

Answer 18

true

Question 19

Which one of the following statements about mutations in the lactose operon is not correct?

Answer 19

In cells containing one mutant and one normal copy of lacO, lacZ and lacY are expressed only in the absence of lactose.

Question 20

All CpG sites located near the promoter region of protein coding genes are methylated.

Answer 20

false

Question 21

Which of the following is not an accurate description of events leading to the lysogenic pathway following viral infection in a bacterium?

Answer 21

Reduction in the concentration of cI protein is the most important contributor to lysogeny.

Question 22

Primary RNA transcripts are always spliced in the same fashion in order to maintain continuity.

Answer 22

false

Question 23

Which of the following statements about transcription in prokaryotes is incorrect?

Answer 23

In prokaryotes, the RNA polymerase complex will bind at the promoter in the presence or absence of an activator protein and transcription will proceed.

Question 24

When a group of functionally related genes located next to one another along the bacterial DNA is transcribed together as a single molecule of mRNA, that mRNA is called a _________________ RNA.

Answer 24

polycistronic

Question 25

Untranslated regions of the mRNA transcript may interact with motor proteins to enhance transport of the mRNA to a distinct region of the cell; or these regions may interact with proteins that repress the translation of the mRNA.

Answer 25

true

Question 26

Which of the following does not occur during RNA processing?

Answer 26

the removal of all exons during RNA splicing