Chromatin Remodelling: Histone Modifications

Question 1

Which of the following best defines euchromatin?

Answer 1

a) A region of DNA in which the chromatin has an open structure that permits transcription.
b) A region of DNA in which the chromatin has an open structure that prevents transcription.
c) A region of DNA in which the chromatin has a closed structure that permits transcription.
d) A region of DNA in which the chromatin has a closed structure that prevents transcription.
e) The region of DNA that wraps around a single nucleosome.

Question 2

Which of the following statements about histone acetylation is TRUE?

Answer 2

a) HDAC proteins add acetyl groups to histones.
b) HAT proteins remove acetyl groups to histones.
c) Acetylation makes histones less positively charged, reducing their interaction with DNA and increasing histone mobility.
d) Acetylation of histones predominantly occurs on leucine residues.
e) Acetylated histones act as binding sites for proteins containing chromodomains.

Question 3

Which of the following statements about histone modifications are TRUE?

Answer 3

a) PRC2 methylates H3K27 creating a PRC1 binding site.
b) PRC1 ubiquitinates H2A blocking transcriptional elongation.
c) MLL methylates histone H3K4.
d) NURF binds H3K4me3 and remodels chromatin allowing RNA polymerase II to pass and continue transcription.
e) All of the above statements are true.