Exam 12: DNA Organization in Chromosomes

Chromosomal regions that represent evolutionary vestiges of duplicated copies of genes that have underdone sufficient mutations to render them untranscribable are called_________ .

When native chromatin is digested with micrococcal nuclease,what significant result occurs?

Chromatin of eukaryotes is organized into repeating interactions with protein octamers called nucleosomes.Nucleosomes are composed of which class of molecules?

List the components of a nucleosome.

How was it experimentally determined that "puffs" are transcriptionally active?

This figure represents supercoiled,circular,double- stranded DNA: If this molecule of DNA originated as a linear molecule with a linking number L of 30,which was then circular unwound,the L for the unwound circular molecule would be_________ .

What are histones,and how are they arranged in nucleosomes?

In addition to highly repetitive and unique DNA sequences,a third category of DNA sequences exists.What is it called,and what types of elements are involved in it?

What is the relationship between topoisomers?

A particular variant of the lambda bacteriophage has a DNA double- stranded genome of 51,365 base pairs.How long would this DNA be?

Viral chromosomes exist in a variety of conformations and can be made up of _________

Although mutations have been observed in many different genes,they have not been isolated in histones.Why does this seem reasonable? If one wanted to produce antibodies to histones,would it be an easy task? Explain your answer.

The condition that some organisms contain much larger amounts of DNA than are apparently "needed" and that some relatively closely related organisms may have vastly different amounts of DNA is more typical in _________.

Explain how linear DNA can be supercoiled.

Briefly describe the makeup of VNTRs variable number tandem repeats).

Describe the chromosomal conformations of ΠX174 and polyomaviruses.

How do VNTRs relate to DNA fingerprinting?

What is unusual about the amino acid composition of histones? How is the function of histones related to the amino acid composition? Of which histones are nucleosomes composed?

Describe the basic structure of a nucleosome.What is the role of histone H1?

Approximately how much of the mammalian genome is composed of repetitive DNA?