Kandpal - Chromatin Structure and Transcription

Question 1

What are Eukaryotic gene expressions regulated by?

Answer 1

Chromosome structure

Question 2

Can gene’s be turned on and off?

Answer 2

Yes, by switching between 2 alternative structures of a chromosome.

Question 3

What is another name for organized structure of a chromosome?

Answer 3

Chromatin

Question 4

If DNA is inactive, what is another name?

Answer 4

Heterochromatin

Question 5

What is another name for an active sequence?

Answer 5

Euchromatin

Question 6

How many units of an octamer of histones are required?

Answer 6

146 bp

Question 7

What is the suffix for short arm metaphase chromosome?

Answer 7

P

Question 8

What is the suffix for a long arm metaphase chromosome?

Answer 8

Q

Question 9

How man turns of DNA does a nucleosome have?

Answer 9

2 turns

Question 10

What is the shape of a nucleosome?

Answer 10

Flat disk

Question 11

Name the 4 core histones.

Answer 11

H2A, H2B, H3 and H4

Question 12

Out of the core histones, which ones are most conserved?

Answer 12

H3 and H4. While H2A and H2B show variation

Question 13

Out of the 4 core histones which one is the linker histone?

Answer 13

H1

Note: Also the compacter.of DNA

Question 14

Name the 3 histone modifiers.

Answer 14

1. Acetylation
2. Methylation
3. Phosphorylation

Question 15

During the histone modification, which one adds and which one removes acetyl?

Answer 15

HAT’s (HIstone Acetyl Transferases) for addition.

HDAC’s (Histone Deacetylase Complexes) for removal.

Question 16

During the histone modification, which one adds methyl and removes methyl?

Answer 16

Histone methyl transferase for addition.

Histone demethylases removes methyl

Question 17

What reduces the positive charge of Lysine?

Answer 17

Acetylation - loosening of chromatin structure

Question 18

What is the name of modification of histones which occur in different combinations?

Answer 18

Histone Code

Question 19

When decondensation of Interphase of chromosomes occurs, what portion of the chromosome becomes highly expressed?

Answer 19

The loop gets exaggerated.

Question 20

Which phase of interphase condenses chromosomes?

Answer 20

Metaphase

Question 21

What phase decondenses chromosomes?

Answer 21

Interphase

Question 22

Is epigenetic always controlled by DNA sequence?

Answer 22

No. It never is.

Question 23

What is epigenetic control brought about by?

Answer 23

Modification of DNA bases and histones.

Question 24

What is histone modification?

Answer 24

It is acetylation and found in active chromatin

Question 25

T or F. Methylation of cytosines in CpG dinucleotides of promoter truns off the promotor.

Answer 25

True.

Question 26

During what time of fertilization does inactivation occur?

Answer 26

Within 2 weeks of fertilization. 500 to 1000 cells

Question 27

What type of RNA does inactivation mediated by?

Answer 27

Xist RNA (Inactivates 1 chromosome)

Question 28

T or F. Majority of genes are expressed equally.

Answer 28

True

Question 29

What is called when a gene is not expressed?

Answer 29

Imprinting.

Question 30

What is PWS?

Answer 30

Prader-Willi Syndrome Mild to moderate mental retardation Hypotonia and poor feeding in infancy Short stature, small hands and feet and small external genitalia Compulsive overeating and massive obesity Microdeletion of 15q11-q13 Deletion inherited from father (maternal allele of the gene is imprinted).

Question 31

What is AS?

Answer 31

``` Angelman Syndrome Severe mental retardation with absence of speech Seizures Jerky gait Large mouth with a prominent tongue Happy disposition and excessive laughter Microdeletion of chromosome 15q11-q13 Deletion inherited from mother (paternal copy of the gene is imprinted). ```

Question 32

What is MECP2 and is its function?

Answer 32

Methyl cytosine binding protein encoding gene

Question 33

What is Rett Syndrome?

Answer 33

It is a X-linked disorder limited to females. | Some causes are inability to speak and walk

Question 34

What does DNMT3 stand for and what kind of syndrome is it?

Answer 34

De Novo Methyltransferase. It is a immunodeficiency, chromosome instability and facial anomalies

Question 35

What occurs when there is a mutation in ATRX?

Answer 35

Mental retardation, urogenital abnormalities and alpha thallasemia.