3.3 DNA Organization within Chromosomes

Question 1

What do bacterial cells contain for chromosomes?

Answer 1

nucleoid

Question 2

What is a nucleoid?

Answer 2

compact double-stranded DNA molecule

Question 3

What is the most researched bacteria?

Answer 3

e. coli

Question 4

How long is E. coli’s chromosome?

Answer 4

1mm in length

Question 5

Why is E. coli a good research tool?

Answer 5

DNA can be easily isolated and purified for use in cloning strategies

Question 6

When a eukaryotic cell is not actively dividing how is the DNA?

Answer 6

uncoiled in chromatin

Question 7

What are histones?

Answer 7

proteins around which DNA is wrapped

Question 8

Does chromatin have histones?

Answer 8

yes

Question 9

What is the purpose of histones during cell division?

Answer 9

help the chromatin to recoil and condense

Question 10

How “long” can human DNA be stretched?

Answer 10

6 feet

Question 11

What is the length contraction for each chromatin fiber in humans?

Answer 11

10,000 times

Question 12

What charge do histones have?

Answer 12

positive

Question 13

How do histones interact with DNA?

Answer 13

positive charge allows them to bind tightly through electrostatic interactions with the negatively charged DNA

Question 14

What is the phase interphase of cell division?

Answer 14

nondividing portion of the cell cycle

Question 15

What does DNA look like during interphase?

Answer 15

small amount of DNA is coiled around an octomer of histones

Question 16

What is a nucleosome?

Answer 16

octomer DNA bundle

Question 17

What is a solenoid?

Answer 17

six nucleosome packaged into a bundle

Question 18

What is the purpose of H1 histone?

Answer 18

responsible for packing nucleosome into the solenoid

Question 19

Once mitosis begins how are the solenoids further compacted?

Answer 19

into looped domains and then into chromatid

Question 20

What is the process that allows DNA-protein interactions?

Answer 20

chromatin remodeling