10.) In complex eukaryotes, what relationships exist betweenthese DNA elements?
a. Centromeres, tandemly repeated DNA and constitutiveheterochromatin
b.Interphase chromosomes, mitotic chromosomes, nucleosomes,histones.
c. Supercoiling and chromatin
11.) Which of the following statements is true?
a. Histones are an example of a sequence-specific DNA-bindingprotein.
b. The majority of human DNA is not known to be useful to ourcells.
c. Human females have 23 different chromosomes, whereas humanmales have 24.
d. Because nucleosomes play a key role in packaging DNA intochromosomes, they bind to the DNA molecule very tightly and, oncethey are assembled, they cannot be moved.
e. A nucleosome consists of DNA wrapped around eight histoneproteins, plus a short segment of linker DNA.
f. Nucleosomes are found only in mitotic chromosomes.
g. Histone proteins have a high proportion of positively chargedamino acids, which bind tightly to the negatively charged DNAbackbone.
12.) Micrococcal nuclease (MNase) is an enzyme thatnon-specifically cuts exposed DNA in its phosphodiester backbone.Brief digestion of eukaryotic chromatin with micrococcal nucleasegives DNA fragments ~200 bp long. You repeat the experiment, butincubate the samples for a longer period of time. This longerdigestion yields 146 bp fragments. Why? Explain, using a diagram ofthe packaging of DNA by histone proteins into the basic unit ofchromatin.
