Chapter 32. The Control of Gene Expression in Eukaryotes

Question 1

A highly conserved group of small basic proteins found in eukaryotes in association with DNA to form nucleosomes.

Answer 1

histones

Question 2

A domain consisting of a four-helix bundle that binds peptides containing acetyllysine. Also called a bromodomain.

Answer 2

acetyllysine-binding domain

Question 3

Proteins that bind microRNA, forming a complex which then degrades mRNA complementary to the microRNA.

Answer 3

Argonaute family proteins

Question 4

A steroid, such as testosterone, that acts through the androgen receptor to stimulate genes that enhance the development of lean muscle mass.

Answer 4

anabolic steroid

Question 5

A molecule that binds to a receptor protein but does not trigger the signaling pathway. Such molecules are like competitive inhibitors for enzymes.

Answer 5

antagonist

Question 6

Molecules that bind to receptor proteins and trigger signaling pathways.

Answer 6

agonists

Question 7

Cells within an organism that have the same genetic makeup but have different properties owing to differences in gene expression.

Answer 7

cell type

Question 8

A protein that assists RNA polymerase in the initiation of RNA synthesis; binds to a specific promoter element.

Answer 8

transcription factor

Question 9

The repeating unit of chromatin that consists of 200 base pairs of DNA and two each of the histones H2A, H2B, H3, and H4.

Answer 9

nucleosomes

Question 10

Particles resulting from micrococcal nuclease digestion of nucleosomes, consisting of 140-bp DNA and the histone octamer of a nucleosome.

Answer 10

nucleosome core particles

Question 11

Nucleoprotein chromosomal material consisting mainly of DNA and histones.

Answer 11

chromatin

Question 12

DNA binding domains of some eukaryotic proteins that are similar to the prokaryotic helix-turn-helix domain. Homeodomain proteins often form heterodimeric structures, sometimes with other homeodomain proteins, that recognize asymmetric DNA sequences.

Answer 12

homeodomain

Question 13

A means of controlling gene expression in eukaryotes in which each transcription factor, rather than acting on its own to effect transcription, recruits other proteins to build up large complexes that regulate the transcription machinery.

Answer 13

combinatorial control

Question 14

An enzyme that catalyzes the attachment of acetyl groups from acetyl CoA to specific lysine residues in the amino-terminal domains of histones. These enzymes play crucial roles in the modification of chromatin structure that enhances transcription.

Answer 14

histone acetyltransferase (HAT)

Question 15

Proteins that activate transcription by binding to specific transcription factors and then catalytically modifying chromatin components.

Answer 15

coactivator

Question 16

A member of a large family of transcription factors that, on binding of a signal molecule such as a steroid hormone, modify the expression of specific genes by binding to control elements in the DNA.

Answer 16

nuclear hormone receptor

Question 17

A technique for identifying the binding sites of DNAbinding proteins. The protein is cross-linked to DNA to which it is bound in chromatin, and the DNA is fragmented into small pieces. Antibodies to the bound protein are used to isolate the chromatin fragments with the bound protein. The cross-linking is reversed, and the DNA is isolated and characterized.

Answer 17

chromatin immunoprecipitation (ChIP)

Question 18

Regions of the chromosome that are especially sensitive to digestion by exogenous DNAses; such regions are usually located at the 5’ end of actively transcribed genes.

Answer 18

hypersensitive sites

Question 19

An iron-sensitive protein that regulates the translational capability of ferritin mRNA and the stability of transferrin receptor mRNA by binding to a stem-loop structure called an iron-response element in the mRNA molecule.

Answer 19

IRE binding protein (IRP)

Question 20

DNA sequences that have no promoter activity themselves but that can greatly enhance the activity of other promoters; enhancers can exert their stimulatory effect over a distance of several thousand nucleotides.

Answer 20

enhancers

Question 21

Regions of DNA rich in the sequence CpG, usually located at the 5’ region of genes; the cytosine bases of these islands can be methylated to inhibit transcription of the associated gene.

Answer 21

CpG islands

Question 22

Pluripotent stem cells, which have the ability to differentiate into many different cell types on appropriate treatment, generated by introducing genes encoding four transcription factors into skin cells called fibroblasts.

Answer 22

induced pluripotent stem (iPS) cell

Question 23

A domain consisting of a four-helix bundle that binds peptides containing acetyllysine. Also called an acetyllysine-binding domain.

Answer 23

bromodomain

Question 24

The relative absence of 5-methylcytosines near the transcription start site of genes that are actively expressed.

Answer 24

hypomethylation

Question 25

Large protein complexes, which contain domains homologous to those of helicases, that utilize the free energy of ATP hydrolysis to shift the positions of nucleosomes along the DNA and to induce other conformational changes in chromatin.

Answer 25

chromatin-remodeling engine

Question 26

An enzyme that contributes to transcriptional repression by deacetylation of acetylated lysine residues in histones.

Answer 26

histone deacetylase

Question 27

A complex of 25 to 30 subunits conserved from yeast to human beings, that acts as a bridge between transcription factors and promoter-bound RNA polymerase II.

Answer 27

mediator

Question 28

A DNA-binding unit that comprises tandem sets of small domains, each of which binds a zinc ion through conserved sets of two cysteine and two histidine residues.

Answer 28

Cys2His2zinc-finger domain

Question 29

A stem-loop structure found in the mRNAs for ferritin and transferrin receptor that interacts with the IRE-binding protein and regulates the translation of the mRNAs.

Answer 29

iron-response element (IRE)

Question 30

RNA molecule 22-nucleotides in length that possesses the regulatory activity when bound to members of a class of proteins called the Argonaute family.

Answer 30

microRNA (miRNA)

Question 31

An iron-storage protein found primarily in the liver and kidneys.

Answer 31

ferritin

Question 32

A eukaryotic DNA binding unit that consists of a pair of long a helices. Because these pairs are often stabilized by appropriately spaced leucine residues, these structures are often referred to as leucine zippers.

Answer 32

basic-leucine zipper (bZip) protein

Question 33

A membrane protein that binds iron-loaded transferrin and initiates its entry into cells.

Answer 33

transferrin receptor

Question 34

One of a group of proteins, many of which contain bromodomains, that bind to the TATA-box-binding protein to form a complex required for RNA transcription.

Answer 34

TATA-box-binding protein associated factor (TAF)

Question 35

Specific DNA sites containing the consensus sequence 5’-AGGTCANNNTGACCT-3’ that serve as binding sites for the estrogen receptor.

Answer 35

estrogen response element (ERE)

Question 36

A transport protein that carries iron in the blood serum.

Answer 36

transferrin

Question 37

Molecules, such as tamoxifen, that bind to the estrogen receptor but do not trigger activation of the signal pathway.

Answer 37

selective estrogen receptor modulator (SERM)