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Euk Genes > Chromosomes and Chromatin > Flashcards

Chromosomes and Chromatin Flashcards

1
Q

Network of fibres found throughout inside of cell nucleus

A

Nuclear matrix

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2
Q

DNA attached to the nuclear matrix at __________

A

Matrix attachment regions (MARS)

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3
Q

Chromosomal banding pattern

A

G-bands

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4
Q

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

A

Bands, interbands

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5
Q

DNA of metaphase chromatin is ___________

A

Negatively supercoiled

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6
Q

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

A

Euchromatin

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7
Q

Aggregate of heterochromatin from different chromsosomes

A

Chromocenter

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8
Q

_____ cleaves linked DNA and releases individual nucleosomes from chromatin

A

MNase

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9
Q

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

A

Core, linker

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10
Q

Nucleosome contains ______ and ________

A

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

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11
Q

Histone octamer structure

A

H3-H4 tetramer associated with two H2A and H2B dimers

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12
Q

All core histones have the structural motif of ________

A

Histone fold

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13
Q

Histone code hypothesis

A

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

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14
Q

Bromodomain function

A

Used to recognize acetylated sites on histones

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15
Q

Protein motifs that recognize methyl lysines

A

Chromodomains, PHD domains, Tudor domains

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16
Q

Primary structure of chromatin

A

10-nm fiber string of nucleosomes

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17
Q

Secondary structure of chromatin

A

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

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18
Q

Replication of chromatin requires assembly of ________

A

Nucleosomes

19
Q

Common cause of nucleosome positioning

A

When proteins binding to DNA establish a boundary

20
Q

Translational positioning

A

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

21
Q

Rotational positioning

A

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

22
Q

Histone octamers disassembled ahead of ________ to remove nucleosomes

A

Transcription

23
Q

Where are hypersensitive sites found?

A

Promoters of expressed genes

24
Q

Locus control regions (LCR)

A

Regulate gene clusters

25
Q

Where are LCR found?

A

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

26
Q

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

A

Direct interactions

27
Q

TADs

A

Topologically associated domains

28
Q

How are mammalian chromosomes organized?

A

As strings of TADs about 1 Mb in size

29
Q

Boundary regions between TADs contain _______

A

Insulator elements

30
Q

Specialized chromatin structure that contain hypersensitive sites

A

Insulators

31
Q

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

A

Block

32
Q

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

A

Centromere

33
Q

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

A

Acentric fragment

34
Q

Microtubule organizing center (MTOC)

A

Region from which microtubules emanate, in animal cells the centrosome

35
Q

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

A

Mitotic spindle, kinetochore

36
Q

Centromeres characterized by…

A

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

37
Q

Function of ever-present repetitive centromeric DNA?

A

Unknown

38
Q

Telomere required for ________

A

Stability of the chromosome end

39
Q

Telomere consists of __________

A

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

40
Q

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

A

Telomerase

41
Q

Telomerase expressed in _________

A

Actively dividing cells

42
Q

Loss of telomerase results in _________

A

Senescence

43
Q

Prevent crossing over between telomeres

A

Mismatch-repair system

Euk Genes (13 decks)

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