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Flashcards in Genome organization Deck (28)
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1

Define synteny

Refers to two genes that are on the same chromosome

2

What percentage of the genome codes for protein

1.5%

3

What is the average length of an exon

100-200

4

What percentage of a gene is repetitive DNA?

50%

5

What is the average size of a gene?

27k

6

What are the four levels of DNA compaction?

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

7

What is the diameter of a nucleosome?

10 nm

8

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

H2A, H2B, H3, H4

9

How many bp wrap around the histone?

146-147

10

In a complete nucleosome, how many bp?

200

11

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

Spacing between histones

12

Name four covalent modifications to histone tails

1. Lysine acetylation
2. Lysine methylation
3. Serine phosphorylation
4. Ubiquitination

13

What enzyme carries out histone acetylation

histone acetyl-transferase

14

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

Histone H1

15

The highly condensed form of chromatin

heterochromatin

16

The less condensed form of chromatin

euchromatin

17

Define constitutive heterochromatin

heterochromatin is tightly packed all the time

18

Define facultative heterochromatin

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

19

Positional effect

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

20

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

Isolators: HS4 sequence

21

What is a "reader writer" complex?

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

22

What are tandemly repeated short sequences in the centromere called?

alpha satellite DNA

23

What is different about nucleosomes in the centromere?

They have a histone H3 variant named CENP-A

24

How many nucleotide pairs in an alpha satellite DNA monomer

171

25

What are two examples of interphase chromosome compaction

1. lampbrush chromosomes (amphibian oocytes)
2. polytene chromosomes (drosophila salivary glands)

26

What is the highest level of chromatin compaction?

mitotic chromosomes

27

What are two roles of mitotic chromosome compaction?

1. it untangles sister chromatids
2. protects DNA molecules while being pulled to daughter cells

28

What group of proteins are used to compact interphase chromosomes?

condensins