Chapter 8 Review

Question 1

From the sequencing of the human genome, we believe that there are approximately 21,000 protein-coding genes in the genome, of which 1500–3000 are transcription factors. If every gene has a tissue-specific and signal-dependent transcription pattern, how can such a small number of transcriptional regulatory proteins generate a much larger set of transcriptional patterns?

Answer 1

Transcription regulators are generally used in combinations, thereby increasing the possible regulatory repertoire of gene expression with a limited number of proteins.

Question 2

Many transcriptional regulators function together to decide the expression level of a particular gene. This describes the concept of

Answer 2

combinatorial control.

Question 3

MicroRNAs block the expression of a specific gene product by binding to the ___________ and inhibiting ___________.

Answer 3

mRNA; translation

Question 4

Gene transcription patterns can also be transmitted across generations through positive _________loops that can involve a transcription regulator activating its own transcription in addition to other genes. These mechanisms all allow for cell __________, a property involving the maintenance of gene expression patterns important for cell identity.

Answer 4

feedback, memory

Question 5

MicroRNAs are non-coding RNA that are incorporated into a protein complex called _____, which searches the _____ in the cytoplasm for sequence complementary to that of the miRNA. When such a molecule is found, it is then targeted for _______.

Answer 5

RISC, mRNA, destruction

Question 6

_______________ control determines which completed mRNAs in the cell nucleus exported to the cytoplasm.

Answer 6

mRNA transport and localization

Question 7

Which of the following is the main point of control for regulating gene expression levels?

Answer 7

transcription

Question 8

The transmission of information important for gene regulation from parent to daughter cell, without altering the actual nucleotide sequence, is called __________ inheritance. This type of inheritance is seen with the inheritance of the covalent modifications on ____________ proteins bound to DNA these modifications are important for reestablishing the pattern of chromatin structure found on the parent chromosome.

Answer 8

epigenetic, histone

Question 9

A housekeeping gene is a gene whose cellular function is

Answer 9

important for processes found in all cell types.

Question 10

_______________ control determines which mRNAs in the cytoplasm are transcribed by ribosomes.

Answer 10

mRNA degradation

Question 11

_______________ control activates, inactivates, or compartmentalizes specific protein molecules after they have been made.

Answer 11

protein degradation control and proactivity

Question 12

Cells have a defense mechanism for destroying “foreign” double-stranded RNAs, many of which are produced by viruses. It makes use of ________ RNAs that are produced from the foreign RNAs in a process called RNAi

Answer 12

siRNAs

Question 13

_______________ control determines how the primary RNA transcripts is spliced or otherwise processed.

Answer 13

RNA processing

Question 14

1

Answer 14

activator protein

Question 15

Protein-DNA interactions are among the tightest and most specific Molecular Interactions known in biology. True or False?

Answer 15

True

Question 16

miRNAs, tRNAs, and rRNAs all _____________.

Answer 16

do not code for proteins.

Question 17

The figure below depicts which of the following mechanisms that cells use to maintain their identity through cell divisions?

Answer 17

positive feedback

Question 18

Cell differentiation is achieved by changes in ______.

Answer 18

Gene expression

Question 19

If lactose and glucose are both available to a bacterial cell, which carbon source(s) will be used?

Answer 19

glucose

Question 20

_____ is a complex process by which cells selectively direct the synthesis of the many thousands of proteins and RNAs encoded in their genome.

Answer 20

Gene expression

Question 21

Transplanting the nucleus of an epithelial cell into an egg cell lacking genetic information leads to the formation of

Answer 21

a normally developing embryo.

Question 22

The genes of a bacterial ___________ are transcribed into a single mRNA. Many bacterial promoters contain a region known as an _____________, to which a specific transcription regulator binds.

Answer 22

operon, operator

Question 23

In principle, gene expression can be controlled at any of the steps between a gene and its ultimate functional product. For the majority of genes, however, the __________ is the most important point of control. Because this control point can ensure that no unnecessary intermediates are synthesized.

Answer 23

transcription

Inhibiting the transcription of genes that are not currently needed help keep unnecessary intermediates from being synthesized.

Question 24

2

Answer 24

mediator

Question 25

_______________ control selectively destabilizes certain mRNA molecules in the cytoplasm.

Answer 25

translational

Question 26

Another way to inherit chromatin structure involves DNA __________, the covalent modification that occurs on cytosine bases that typically turns off the transcription of a gene.

Answer 26

methylation

Question 27

_______________ control determines when and how often a given gene is transcribed.

Answer 27

transcriptional

Question 28

All organism’s ____________ encodes all of the RNA and protein molecules that are needed to make its cell. Nearly all the cells of a multicellular organism contain the same ___________.

Answer 28

DNA; genome

Question 29

4

Answer 29

RNA Polymerase

Question 30

RNAi is triggered by the presence of foreign __________ molecules, which are digested by the ________ enzyme into shorter fragments approximately 23 nucleotide pairs in length.

Answer 30

double-stranded RNA, DICER

Question 31

3

Answer 31

general transcription factors

Question 32

How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?

Answer 32

by looping out the intervening DNA between their binding site and the promoter