Chromosomes and Chromatin

Question 1

Network of fibres found throughout inside of cell nucleus

Answer 1

Nuclear matrix

Question 2

DNA attached to the nuclear matrix at __________

Answer 2

Matrix attachment regions (MARS)

Question 3

Chromosomal banding pattern

Answer 3

G-bands

Question 4

In g-bands, ______ are lower in GC content than ______

Answer 4

Bands, interbands

Question 5

DNA of metaphase chromatin is ___________

Answer 5

Negatively supercoiled

Question 6

During interphase, general mass of chromatin is in the form of _________

Answer 6

Euchromatin

Question 7

Aggregate of heterochromatin from different chromsosomes

Answer 7

Chromocenter

Question 8

_____ cleaves linked DNA and releases individual nucleosomes from chromatin

Answer 8

MNase

Question 9

Nucleosomal DNA divided into _____ and _____ DNA depending on susceptibility to MNase

Answer 9

Core, linker

Question 10

Nucleosome contains ______ and ________

Answer 10

200 bp of DNA, two copies of each of core histones (H2A, H2B, H3, H4)

Question 11

Histone octamer structure

Answer 11

H3-H4 tetramer associated with two H2A and H2B dimers

Question 12

All core histones have the structural motif of ________

Answer 12

Histone fold

Question 13

Histone code hypothesis

Answer 13

Combinations of specific histone modifications define function of local regions of chromatin

Question 14

Bromodomain function

Answer 14

Used to recognize acetylated sites on histones

Question 15

Protein motifs that recognize methyl lysines

Answer 15

Chromodomains, PHD domains, Tudor domains

Question 16

Primary structure of chromatin

Answer 16

10-nm fiber string of nucleosomes

Question 17

Secondary structure of chromatin

Answer 17

Interactions between neighboring nucleosomes that promote formation of more condensed fibers, 30-nm fibers folded into higher-order 3D structures

Question 18

Replication of chromatin requires assembly of ________

Answer 18

Nucleosomes

Question 19

Common cause of nucleosome positioning

Answer 19

When proteins binding to DNA establish a boundary

Question 20

Translational positioning

Answer 20

Location of histone octamer at successive turns of double helix, determines sequences in linker regions

Question 21

Rotational positioning

Answer 21

Location of histone octamer relative to turns of the double helix, determines which face of DNA is exposed on nucleosome surface

Question 22

Histone octamers disassembled ahead of ________ to remove nucleosomes

Answer 22

Transcription

Question 23

Where are hypersensitive sites found?

Answer 23

Promoters of expressed genes

Question 24

Locus control regions (LCR)

Answer 24

Regulate gene clusters

Question 25

Where are LCR found?

Answer 25

5' end of a chromosomal domain, consist of multiple DNase hypersensitive sites

Question 26

LCRs control transcription of target genes by ____________, forming looped structures

Answer 26

Direct interactions

Question 27

TADs

Answer 27

Topologically associated domains

Question 28

How are mammalian chromosomes organized?

Answer 28

As strings of TADs about 1 Mb in size

Question 29

Boundary regions between TADs contain _______

Answer 29

Insulator elements

Question 30

Specialized chromatin structure that contain hypersensitive sites

Answer 30

Insulators

Question 31

Insulators are able to ______ passage of effects from enhancers, silencers, and other control elements

Answer 31

Block

Question 32

Constricted region of chromosome that includes site of attachment to the mitotic or meiotic spindle

Answer 32

Centromere

Question 33

Fragment of chromosome that lacks centromere and is lost at cell division

Answer 33

Acentric fragment

Question 34

Microtubule organizing center (MTOC)

Answer 34

Region from which microtubules emanate, in animal cells the centrosome

Question 35

Eukaryotic chromosome held on the ________ by the attachment of microtubules to the ___________

Answer 35

Mitotic spindle, kinetochore

Question 36

Centromeres characterized by...

Answer 36

Centromere-specific histone H3 variant and often have heterochromatin rich in in satellite DNA sequences

Question 37

Function of ever-present repetitive centromeric DNA?

Answer 37

Unknown

Question 38

Telomere required for ________

Answer 38

Stability of the chromosome end

Question 39

Telomere consists of __________

Answer 39

Simple repeating structure with a G-T rich strand that extends beyond A-C strand

Question 40

This enzyme base pairs between RNA template and the protruding single-stranded DNA primer to add tandem repeats to 3' end at each chromosomal terminus

Answer 40

Telomerase

Question 41

Telomerase expressed in _________

Answer 41

Actively dividing cells

Question 42

Loss of telomerase results in _________

Answer 42

Senescence

Question 43

Prevent crossing over between telomeres

Answer 43

Mismatch-repair system