Exam 2 Flashcards

1
Q

What is mainly responsible for the attraction between histones and DNA?

A

Histones have a positive charge and DNA has a negative charge

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2
Q

What is the region of a chromosome where spindle fibers attach?

A

Centromere

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3
Q

What surrounds the centromere?

A

Heterochromatin

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4
Q

What is the physical role of centromeres?

A

Act as the site of assembly for kinetochore

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5
Q

What type of sequences make up euchromatin?

A

Unique

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6
Q

Is crossing over common in euchromatin or heterochromatin?

A

Euchromatin

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7
Q

Is DNA methylation high or low in euchromatin?

A

Low

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8
Q

What type of sequences make up heterochromatin?

A

Repeated

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9
Q

What is the double-stranded DNA in between two nucleosome cores that holds the cores of the histone together?

A

Linker DNA

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10
Q

When is heterochromatin replicated?

A

Late S phase

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11
Q

What are centromeres necessary for?

A

Chromosome seperation

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12
Q

Briefly describe the structure of a nucleosome.

A

Segment of DNA wound around eight core histone proteins

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13
Q

Is transcription more frequent in euchromatin or heterochromatin?

A

Euchromatin

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14
Q

Is DNA methylation high or low in heterochromatin?

A

High

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15
Q

What is the function of a telomere?

A

Protects the end of chromosomes from deterioration and from fusion with neighboring chromosomes

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16
Q

What is the multiprotein structure responsible for the events during chromosome seperation?

A

Kinetochore

17
Q

What health relevance do shortened telomeres have?

A

Shorter life span and an increased incidence of disease

18
Q

Where is Euchromatin located?

A

On chromosome arms

19
Q

What does DNase I sensitivity correlate with?

A

Gene activity

20
Q

What histone modification is commonly occuring in heterochromatin?

A

Hypoacetylation

21
Q

What is a small cylindrical cell organelle, located near the nucleus in the cytoplasm of most eukaryotic cells, that divides in perpendicular fashion during mitosis?

A

Centriole

22
Q

What histone modification is commonly occuring in euchromatin?

A

Hyperacetylation

23
Q

Where is heterochromatin located?

A

At centromeres, telomeres, and other specific places

24
Q

What is the basic unit of DNA packaging in eukaryotes?

A

Nucleosome

25
Q

When is euchromatin replicated?

A

Throughout the S phase

26
Q

What occurs when DNA is overrotated and the helix turns on itself?

A

Positive supercoiling

27
Q

What occurs when DNA is underrotated and the helix twists on itself in the opposite direction?

A

Negative supercoiling

28
Q

What enzyme is responsible for adding and removing turns in the coil?

A

Topoisomerase