Gene Expression

Question 1

Changes to the chemical groups that associate with DNA profoundly affect which parts of the genome are accessible to transcription factors and under which conditions. Such changes to the molecules that bind to DNA that are transmitted to daughter cells when the cell divides are termed _________literally, “__________.”

Answer 1

epigenetic

outside the gene

Question 2

Specific classes of ______ and ______ molecules carry out epigenetic changes, and much of the genome encodes these modifiers of gene expression.

Answer 2

proteins and RNA

Question 3

do not alter the DNA base sequence, although they are passed from one cell generation to the next.

Answer 3

Epigenetic changes

Question 4

A more complete portrait of gene expression emerges through_______, which considers all proteins made in a cell, tissue, gland, organ, or entire body

Answer 4

proteomics

Question 5

_______patterns change over time and in different cell types.

Answer 5

Gene expression

Question 6

The subunit composition of_____\ changes in the embryo, fetus, and after birth.

Answer 6

hemoglobin

Question 7

As a pancreas forms, ________ diverge from shared stem cells and their daughters specialize.

Answer 7

progenitor cells

Question 8

tracks all of the proteins in a cell, tissue, organ, or organism under specific conditions.

Answer 8

Proteomics

Question 9

Much of the control of gene expression occurs in two general processes.

Answer 9

chromatin remodeling

microRNAs, bind the 3′ ends of certain mRNAs, preventing their translation into protein

Question 10

_____, interactions of the histone proteins associated with DNA with other chemical groups expose some sections of DNA to transcription factors and shield other sections, blocking their expression.

Answer 10

chromatin remodeling

Question 11

______, bind the 3′ ends of certain mRNAs, preventing their translation into protein.

Answer 11

microRNAs

Question 12

play a major role in exposing DNA when and where it is to be transcribed, and shielding it when it is to be silenced.

Answer 12

Histones

Question 13

enzymes add or delete small organic chemical groups to histones in a process called

Answer 13

chromatin remodeling

Question 14

adds or removes certain organic chemical groups to or from histones. The pattern of binding controls whether the DNA wrapped around the histones is transcribed or not.

Answer 14

Chromatin remodeling

Question 15

The three major types of small molecules that bind to histones are

Answer 15

acetyl groups, methyl groups, and phosphate groups

Question 16

The key to the role histones play in controlling gene expression lies in_________. They bind to very specific sites on certain histones, particularly to the amino acid lysine.

Answer 16

acetyl groups (CH3 CO2 )

Question 17

a group of proteins called an_______ attracts the enzyme (acetylase) that adds acetyl groups to specific lysines on specific histones.

Answer 17

enhanceosome

Question 18

Adding______ groups to these lysines neutralizes their positive charge.

Because DNA carries a negative charge, this change moves the histones away from the DNA, enabling transcription factors to enter, bind, and begin transcription.

Answer 18

acetyl

Question 19

Enzymes called______ remove acetyl groups, which shuts off gene expression.

Answer 19

deacetylases

Question 20

are also added to or taken away from histones. When it binds to a specific amino acid in a specific histone type, a protein is attracted that shuts the DNA off.

Answer 20

Methyl groups (CH3 )

Question 21

As ______are added, methylation spreads from the tail of one histone to the adjacent histone, propagating the gene silencing.

Answer 21

CH 3groups

Question 22

Methyl groups also control gene expression by binding to______ at about 10,000 places in the genome.

Answer 22

cytosines

Question 23

These changes in gene expression are heritable from cell generation to cell generation, but they do not alter the DNA base sequence—that is, they are_______.

Answer 23

epigenetic

Question 24

Addition and removal of acetyl groups, methyl groups, or phosphate groups are examples of

Answer 24

epigenetic changes

Question 25

Effects of _______ can sometimes be seen when MZ (identical) twins inherit the same diseasecausing genotype, but only one twin is sick.

The reason for the discordance may be different patterns of______ of the gene.

Answer 25

methylation

Question 26

__________histones allow transcription to begin.

Answer 26

Acetylated

Question 27

determines which genes are transcribed.

Answer 27

Chromatin remodeling

Question 28

act later in gene expression, preventing the translation of mRNA transcripts into protein.

Answer 28

MicroRNAs

Question 29

belong to a class of RNA molecules called noncoding RNAs, so-named because they were not among the first three major classes of RNA described (mRNA, tRNA, and rRNA).

Answer 29

MicroRNAs

Question 30

Control of gene expression._______ opens to allow transcription factors to bind, whereas______ bind to specific mRNAs, blocking their translation into protein.

Answer 30

Chromatin

microRNAs

Question 31

(3) groups bind to histone proteins, controlling transcription

Answer 31

Acetyl, phosphate, and methyl

Question 32

(2) groups turn on transcription;(1) groups turn it off.

Answer 32

Acetyl and phosphate

methyl

Question 33

bind to the control regions of specific mRNAs, blocking translation.

Answer 33

MicroRNAs