Chapter 6.2

Question 1

What are the different types of histones that wrap around DNA? How many copies

Answer 1

• H2A, H2B, H3, H4 and H1

- >two copies wrap around DNA

Question 2

What are the functions of H2A, H2B, H3 and H4 histone proteins?

Answer 2

• they wrap around 200 base pairs of DNA

- >forming a nucleosome

Question 3

What is the function of H1 histone protein

Answer 3

• it seals off the DNA as the DNA leaves and enters the nucleosome
• > therefore, H1 adds stability to the structure

Question 4

Are most nucleoproteins acid-soluble?

Answer 4

• yes

- >therefore, they tend to stimulate processes such as transcription

Question 5

What is heterochromatin

Answer 5

• chromatin that remains compacted during interphase
• > appears dark under light microscopy
• > has DNA with highly repetitive sequences

-note heterochromatin is transcriptionally silent

Question 6

What is euchromatin

Answer 6

• dispersed chromatin
• > appears light under light microscopy
• > contains genetically active DNA
• > uncondensed

Question 7

What is a telomere? What are its functions

Answer 7

• a repeating unit at the end of DNA
• > some of it is lost during every round of replication
• > it is there to make sure that no actual information is lost during every round of replication
• telomeres also have high GC content
• > this prevents unraveling at the end of the chromosomes
• > in some sense, they essentially knot off the end of the chromosome

Question 8

Are centrosomes made up of heterochromatin

Answer 8

• yes

- >it is made up of repeat sequences with high GC content