Chapter 10

Question 1

is the complex of DNA and DNA-binding proteins such as histones.

Answer 1

chromatin

Question 2

Histones are by far the most abundant proteins in chromatin and are organized in repetitive units, known as

composed mainly of a dual tetramer

Answer 2

nucleosomes

Question 3

Is formed by each of the core histones (H2A, H2B, H3 and H4)

Answer 3

tetramer

Question 4

The DNA connecting two consecutive nucleosomes is called

Answer 4

linker DNA

Question 5

formed with 2 copies of all the major histones

can only be formed in the presence of DNA

Answer 5

octamer

Question 6

a structural motif composed of three
alpha helices interconnected by two loops

Answer 6

Histones fold motif

Question 7

head to tail between H3 and H4 or H2A and H2B is at the base of the tight DNA binding to the
histones

Answer 7

dimer of histone folds

Question 8

forms a V-shaped structure including three DNA-binding sites.

Answer 8

each dimer

Question 9

placed in the center of the nucleosome

Answer 9

H1 and linker DNA

Question 10

are arranged with helical pitch of 11 nm, the size of a nucleosome

Answer 10

nucleosome units

Question 11

nucleosome arranged in a spiral shape, with the flat sides of disks are facing each other; linker bent inside the spiral

Answer 11

solenoid model

Question 12

nucleosomes from
two DNA portions twist around a central axis.

suggested by electron microscopy observation

Answer 12

zigzag model

Question 13

Another empirical evidence supporting the
zigzag model is the crystal structure of the

Answer 13

tetranucleosome

Question 14

Similarly, histone-depleted chromosomes* are composed of a

Answer 14

chromosomal scaffold

Question 15

A protein complex with ATPase activity that translocates (i.e., slides) nucleosomes along the DNA.

Answer 15

chromatin remodeling complex

Question 16

A class of enzymes
that covalently modify the N-terminal tails of
histones

Answer 16

histone modifying enzymes

Question 17

The inheritance of
characteristics acquired by means that do not
involve the nucleotide sequence of the parental
chromosomes

Answer 17

epigenetic inheritance

Question 18

is the position of nucleosomes in the genome fully random?

Answer 18

no

Question 19

They all hydrolyze ATP to break some bonds between DNA and nucleosome so that the latter can be either
ejected or repositioned

Answer 19

Chromatin remodeling complexes

Question 20

plays
a major role in altering chromatin structure.

Answer 20

Modification of the N-terminal tails of histones (H3 variants)

Question 21

add an acetyl
group to lysine residues

Answer 21

Histone acetyltransferases

Question 22

recognition of
acetylated residues.

Answer 22

Bromodomains

Question 23

recognition of
methylated residues.

Answer 23

Chromodomain

Question 24

a hypothetical code in which successive covalent modifications of histone tails and DNA trigger chromatin remodeling and transcriptional activation
events.

Answer 24

histone code

Question 25

1st PTM to 2nd PTM to function (activation or repression of transcription)

Answer 25

PTM cross-talk.

Question 26

there will be 4 nucleosome types

Answer 26

1. Parental H3-H4 and parental H2A-H2B
2. Parental H3-H4 and new H2A-H2B
3. new H3-H4 and parental H2A-H2B
4. New H3-H4 and new H2A-H2B

Question 27

can recognize specific
PTMs and then act on nearby nucleosomes, expanding a given PTM pattern

Answer 27

Histone modifying complexes

Question 28

are used to recruit specific histone
modifying complexes.

Answer 28

Epigenetic marks

Question 29

can help maintain a closed state–repressing gene expression

Answer 29

HP1 complex