Chromatin

Question 1

Who discovered chromosome

Answer 1

Flemming

Question 2

What is a chromatin

Answer 2

Condensed form of dsDNA in the nucleus of eukaryotes

Question 3

Two types of chromatin

Answer 3

Euchromatin (lightly stained) and Heterochromatin(darkly stained)

Question 4

Which type of chromatin is transcriptionally inactive

Answer 4

Heterochromatin

Question 5

In Go stage where are the chromatin attached to? Explain in brief

Answer 5

Attached to nuclear lamina of the nuclear matrix by the AT rich region MARs.

Question 6

Centromere

Answer 6

Constricted region of the DNA, doesn’t have any DNA but have repeating sequences. Two type point and regional centromere

Question 7

Regional centromere and eg

Answer 7

Consist of megabase pairs, gives attachment to multiple spindle microtubules. Eg. Alphoid DNA of humans. 5 mb have upto 171bp repeating sequence

Question 8

Point centromere

Answer 8

Made of upto 125bp sequence and attaches to single spindle microtubule.
For eg in Saccharomyces cerevisiea, have CDE1, CDE2 and CDE3

Question 9

Different types of centromere on the basis of position

Answer 9

Metacentric, submetacentric, acrocentric, telocentric

Question 10

The centromere that lies in the middle is called

Answer 10

Metacentric

Question 11

The centremere that appears L shaped during anaphase movement

Answer 11

Submetacentric

Question 12

Centromere at the end of the chromosome

Answer 12

Telocentric

Question 13

What are monocentric and holocentric

Answer 13

The chromosome having single kinetochore is monocentric and chromosome having multiple kinetochore is holocentric

Question 14

Example of holocentric

Answer 14

C. elegans

Question 15

What are telomere and their function

Answer 15

They are the structure that are present at the end of the chromosome. They help in maintaining the integrity of chromosome and ensure that full the replication takes place

Question 16

What is present at the end of telomere

Answer 16

G rich sequence of single stranded 3’ overhang of 50 to 300 nucleotide. Highly conserved.

Question 17

Telomere of human

Answer 17

TTAGGG

Question 18

How many times telomere of human are repeated

Answer 18

300 to 8000 times

Question 19

How are telomeres protected from nucleolytic attack

Answer 19

Shelterin complex

Question 20

How many proteins does shelterin complex have and what are their names

Answer 20

TRF1, TRF2, POT1, TIN2, RAP1 and TPP1

Question 21

What is t loop

Answer 21

It is the end of telomere found in mammals and helps in the stability of chromosome ends.

Question 22

Which protein binds to the telomere sequence

Answer 22

Trf 1 and trf 2

Question 23

How is G tetraplex is formed

Answer 23

Guanine bases associate with one another, and a four guanine associate with one another they form g tetraplex.

Question 24

What are replicons

Answer 24

Replicons are found in chromatin. They have their own origin of replication. They are typically small, 40 kb to 100 kb.

Question 25

How many origin of replication sides does human have

Answer 25

30,000 ORI

Question 26

Who coined the term chromosome

Answer 26

Waldayer

Question 27

Which is the largest chromosome?

Answer 27

Chromosome 1

Question 28

What are histones and their two categories

Answer 28

Histones are small basic and very conserved proteins. Classified into replication dependant and replication independent histones.

Question 29

Which are the replication dependent histones? Which one among them are the most conserved?

Answer 29

H1, H2A, H2B, H3 and H4. H3 and H4 are the most conserved.

Question 30

Which histone shows appreciable variation between species?

Answer 30

H1

Question 31

How many H1 histone subtypes mammal contain?

Answer 31

Eight.

Question 32

Which isoform of H1 histone is present in avian erythrocytes

Answer 32

H5

Question 33

Which type of histone is present throughout the cell cycle

Answer 33

Replication independent histones

Question 34

Which type of histone have poly A tail

Answer 34

Replication independent histones

Question 35

Histones which are Arginine rich

Answer 35

H3 and H4

Question 36

What is the enzyme that cuts DNA between the nucleosome?

Answer 36

MNase (micrococcal nuclease)

Question 37

Where is MNase derived from?

Answer 37

Streptococcus aureus

Question 38

What is the weight in bp of nucleosome and chromatosome

Answer 38

Nucleosome is 200 base pair and chromatosome is 165 base pair

Question 39

What are present in fish sperm and other sperm instead of histones?

Answer 39

Protamine

Question 40

Nucleosomes are separated by which DNA

Answer 40

Linker DNA (50 to 70bp)

Question 41

What are the small positively charged protein which are associated with linker DNA

Answer 41

H1, linker histone

Question 42

What are the histones called that help in incorporation of histones in nucleosomes?

Answer 42

Histone chaperone

Question 43

Name the different types of histone chaperone.

Answer 43

ASF1, HIR protein, CAF1 and NAP1

Question 44

What is the charge of chaperones?

Answer 44

Negative

Question 45

What is the major type of chromatin during interphase and Go phase

Answer 45

30nm fibre

Question 46

Two types of model in 30nm

Answer 46

Solenoid and zigzag model

Question 47

Where does the solenoid model present? Does it have a centre?

Answer 47

In euchromatin and it doesn't have a centre

Question 48

What are the proteinaceous structurs found at the base of metaphase chromosome

Answer 48

Chromosome Scaffold

Question 49

What are the non histone protein in scaffold?

Answer 49

Condensin, kinensin family member and type 2 topoisomerase

Question 50

Where does the scaffold attaches to the fibre?

Answer 50

At the SAR (scaffold attachment region)

Question 51

What are the proteins that are made of SMC?

Answer 51

Condensin

Question 52

What are the core components of SMC

Answer 52

Condensin and cohesin

Question 53

SMC proteins contain of two domains what are these?

Answer 53

Walker A domain (nucleotide binding site) and Walker B domain (catalytic domain)

Question 54

What is the diameter of metaphase chromosome and chromosome

Answer 54

300nm and 700nm

Question 55

Who coined the term euchromatin and heterchromatin

Answer 55

Heitz

Question 56

Where does Euchromatin regions have acetylation and methylation

Answer 56

H3K4 and H3K79

Question 57

Where are Heterochromatin regions marked with deacetylation and methylation

Answer 57

H3K9