DNA Packaging and Organization

Question 1

nucleosomes

Answer 1

where DNA is organized. connected by linker DNA,

Question 2

True or false: Heterochromatin will increase in abundance during the synthesis phase of the cell cycle.

Answer 2

false: Heterochromatin is the tightly-packed, condensed form of chromatin. It would be unlikely to predominate during the synthesis (replication) phase of the cycle, as the DNA must be easily accessible to DNA polymerase and other enzymes during this phase. Euchromatin predominates during the S phase.

Question 3

Select all that apply to complete the following sentence. Histone acetyltransferase:

Answer 3

a. catalyze the transfer acetyl group :Histone acetyl transferase functions to add acetyl groups to histone proteins, a post-translational modification.

b. increase transcription of the DNA associated with the histone: Histone acetyl transferase functions to add acetyl groups to histone proteins, a process that serves as a post-translational modification. This reduces the positive charge held by the basic histone proteins, loosening the DNA-histone conformation and increasing transcriptional activity.

Question 4

tightly packed chromatins

Answer 4

heterochromatin (tight coiled chromatins)

Question 5

loose chromatins

Answer 5

euchromatins (s-phase; allow dna to be readily replicated or transcribed)

Question 6

histones

Answer 6

+ charged at physological pH on their histones tails
- DNA naturally associated with histone proteins
- these interactions are regulated by enzymes that add or remove acetyl groups from + lysine on the histones tails

Question 7

h

Answer 7

h