Genome organization Flashcards

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1
Q

Define synteny

A

Refers to two genes that are on the same chromosome

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2
Q

What percentage of the genome codes for protein

A

1.5%

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3
Q

What is the average length of an exon

A

100-200

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4
Q

What percentage of a gene is repetitive DNA?

A

50%

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5
Q

What is the average size of a gene?

A

27k

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6
Q

What are the four levels of DNA compaction?

A
  1. Nucleosome: beads on a string
  2. 30nm fibers
  3. Interphase chromosomes
  4. M-phase mitosis model
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7
Q

What is the diameter of a nucleosome?

A

10 nm

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8
Q

What are the four different proteins that make up the histone?

A

H2A, H2B, H3, H4

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9
Q

How many bp wrap around the histone?

A

146-147

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10
Q

In a complete nucleosome, how many bp?

A

200

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11
Q

What is an example of a function of the chromatin remodeling complex?

A

Spacing between histones

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12
Q

Name four covalent modifications to histone tails

A
  1. Lysine acetylation
  2. Lysine methylation
  3. Serine phosphorylation
  4. Ubiquitination
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13
Q

What enzyme carries out histone acetylation

A

histone acetyl-transferase

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14
Q

What protein is involved in modifying DNA trajectory upon leaving the nucleosome and forming 30nm fiber sturcture

A

Histone H1

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15
Q

The highly condensed form of chromatin

A

heterochromatin

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16
Q

The less condensed form of chromatin

A

euchromatin

17
Q

Define constitutive heterochromatin

A

heterochromatin is tightly packed all the time

18
Q

Define facultative heterochromatin

A

Applies to a region of the genome that is hetero- in some cell types, and not in others

19
Q

Positional effect

A

The need for a gene to be in the right part of the genome in order to be expressed

20
Q

What is able to block heterochromatin movement, and what is an example of this?`

A

Isolators: HS4 sequence

21
Q

What is a “reader writer” complex?

A

A group of proteins that gather more more proteins which work together to compact DNA and create heterochromatin

22
Q

What are tandemly repeated short sequences in the centromere called?

A

alpha satellite DNA

23
Q

What is different about nucleosomes in the centromere?

A

They have a histone H3 variant named CENP-A

24
Q

How many nucleotide pairs in an alpha satellite DNA monomer

A

171

25
Q

What are two examples of interphase chromosome compaction

A
  1. lampbrush chromosomes (amphibian oocytes)

2. polytene chromosomes (drosophila salivary glands)

26
Q

What is the highest level of chromatin compaction?

A

mitotic chromosomes

27
Q

What are two roles of mitotic chromosome compaction?

A
  1. it untangles sister chromatids

2. protects DNA molecules while being pulled to daughter cells

28
Q

What group of proteins are used to compact interphase chromosomes?

A

condensins