Chapter 8: Control of Gene Expression

Question 1

Although all of the steps involved in expressing a gene can in principle be regulated, what is the most important stage of control for most genes?

Answer 1

transcription initiation

Question 2

Which form of control directly influences which mRNA are selected by ribosomes for the synthesis of proteins?

Answer 2

translational control

Question 3

At any given time, a typical differentiated human cell will express how many of its approximately 19,000 protein-coding genes?

Answer 3

from 5000 to 15,000

Question 4

The transcription initiation site of a eukaryotic gene is found at which location?

Answer 4

where RNA synthesis begins.

Question 5

Determine whether the following statement is true or false: A cell can change the expression of its genes in response to external signals.

Answer 5

True

Question 6

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

Answer 6

a normally developing embryo.

Question 7

A housekeeping gene is a gene whose cellular function is

Answer 7

important for processes found in all cell types.

Question 8

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

Answer 8

transcription.

Question 9

A reporter gene is an experimentally engineered regulatory DNA sequence from a gene of interest that has been fused to a gene that encodes a protein that is easily observed experimentally. Why is this approach useful?

Answer 9

It provides information into where and when a gene is expressed.

Question 10

Determine whether the following statement is true or false: Master regulators such as Ey in Drosophila are so powerful that they can even activate their regulatory networks outside the normal location.

Answer 10

True

Question 11

Clinicians and the public are excited about the prospects of replacing damaged and diseased tissues with patient-derived (autologous) cells. Using autologous cells, as opposed to cells from a donor, avoids complications such as immune rejection. What series of steps could lead to the production of smooth muscle cells from the fibroblasts of a patient?

Answer 11

1. Obtain fibroblasts 2. Use transcription factors to convert fibroblasts to iPS cells. 3. Grow iPS cells in culture 4. Use transcription factors to convert iPS cells to smooth muscle cells.

Question 12

In eukaryotes, which parts of a gene are transcribed into RNA?

Answer 12

introns and exons.

Question 13

In eukaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?

Answer 13

general transcription factors.

Question 14

To begin transcription, eukaryotic RNA polymerase recognizes nucleotide sequences in what region of the DNA?

Answer 14

promoter region.

Question 15

Activators ____ the amount of transcription Repressors _____ the amount of transcription

Answer 15

increase, decrease

Question 16

Activators ___ RNA polymerase Repressors ___ RNA polymerase

Answer 16

recruit, block

Question 17

What determines the nucleotide sequence of a newly transcribed RNA molecule?

Answer 17

complementary base-paring with a DNA during transcription

Question 18

All of the RNA in a cell is made by what process?

Answer 18

transcription

Question 19

Which type of RNA is converted into protein for performing its cellular function?

Answer 19

mRNA

Question 20

In RNA, which nitrogenous base will pair with the base A?

Answer 20

U

Question 21

In eukaryotes, the initiator tRNA always carries which amino acid?

Answer 21

methionine.

Question 22

The translation of an mRNA begins at the start codon. What is the sequence of this codon?

Answer 22

AUG

Question 23

How many nucleotides are necessary to specify a single amino acid?

Answer 23

3

Question 24

Define

Gene

Genetic Code

Transcription Factor

Promoter

General TXN Factors

TBP

Activators

Repressors

Constitutive Genes

Answer 24

Gene: unit of hereditary information that occupies a fixed position on a chromosome.

Genetic Code: each three nucleotides in a row count as a triplet and code for a single amino acid

Transcription Factor: proteins that recognize and bind to specific short DNA sequences, such that their interaction with these sequences, causally affects expression of genes.

Promoter: DNA sequence that initiates gene transcription; includes sequences recognized by RNA polymerase and its accessory proteins.

General TXN Factors: are proteins that help to position Pol II correctly on the promoter, the region of a gene where transcription is initiated, pull aside the two strands of DNA and then move Pol II into the elongation mode.

TBP: Transcription is an essential step in using the information from genes in our DNA to … The site on the DNA from which the first RNA nucleotide is transcribed

Activators: A protein that binds to a specific regulatory region of DNA to stimulate transcription of an adjacent gene.

Repressors: A protein that binds to a specific regulatory region of DNA to prevent transcription of an adjacent gene.

Constitutive Genes: is a gene that is transcribed continually as opposed to a facultative gene, which is only transcribed when needed. A housekeeping gene is typically a constitutive gene that is transcribed at a relatively constant level.