Question 1

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 ________.

Accepted Answer

The presence of excess DNA and large variation in genome size is much more common in eukaryotes than in prokaryotes. Prokaryotes typically have relatively small and compact genomes, whereas eukaryotes can have much larger genomes with varying amounts of non-coding DNA.

Question 2

Describe the chromosomal conformations of φX174 and polyomaviruses.

Accepted Answer

single-stranded DNA, circular; double-stranded DNA, circular, respectively

Question 3

Eukaryotic chromosomes contain two general domains that relate to the degree of condensation. These two regions are ________.

Accepted Answer

Eukaryotic chromosomes contain two general domains that relate to the degree of condensation, called heterochromatin and euchromatin.

Question 4

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?

Accepted Answer

The answer of What is unusual about the amino acid...

Question 5

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

Accepted Answer

The answer of What are histones, and how are they...

Question 6

In human chromosomes, satellite DNA sequences of about 170 base pairs in length are present in tandem arrays of up to 1 million base pairs. Found mainly in centromere regions, these DNA sequences are called ________.

Accepted Answer

The described satellite DNA sequences of about 170 base pairs in length that are present in tandem arrays of up to 1 million base pairs are called alphoid families. These sequences are most commonly found in centromere regions of human chromosomes. Telomeres are the repetitive DNA sequences found at the ends of linear chromosomes. Primers are short nucleotide sequences that are complementary to a DNA template strand and serve as starting points for DNA synthesis. Euchromatic regions are lightly packed chromosomal areas that contain actively transcribed genes. Telomere-associated sequences are specific DNA sequences that are found in close proximity to telomeres.

Question 7

List the components of a nucleosome.

Accepted Answer

The answer of List the components of a nucleosome....

Question 8

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

Accepted Answer

Viral chromosomes can be made up of either DNA or RNA, depending on the specific virus. They do not necessarily contain protein- or lipid-coding sequences, and they do not consist of both DNA and RNA or all three (DNA, RNA, and protein).

Question 9

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.

Accepted Answer

The answer of Although mutations have been observed in many...

Question 10

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

Accepted Answer

The answer of A particular variant of the lambda bacteriophage...

Question 11

In E. coli, the genetic material is composed of ________.

Accepted Answer

In E. coli, the genetic material is composed of circular, double-stranded DNA.

Question 12

What similarities do bacterial chromosomes have with eukaryotic chromosomes?

Accepted Answer

The answer of What similarities do bacterial chromosomes have with...

Question 13

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

Accepted Answer

Nucleosomes are composed of histones, which are a class of proteins that package DNA in eukaryotic cells.

Question 14

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?

Accepted Answer

Moderately repetitive DNA includes different types of transposable elements such as SINEs, LINEs, and VNTRs, which are repeated throughout the genome but not in high numbers. The other options either do not exist (composite DNA, dominant DNA, and permissive DNA) or refer to specific types of sequences (multiple gene families).

Question 15

How does a polytene chromosome differ from a typical eukaryotic chromosome?

Accepted Answer

The answer of How does a polytene chromosome differ from...

Question 16

What are minisatellites and microsatellites?

Accepted Answer

The answer of What are minisatellites and microsatellites?...

Question 17

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

Accepted Answer

The answer of Describe the basic structure of a nucleosome....

Question 18

Compare and contrast the chromosome structure of viruses, bacteria, and eukaryotes.

Accepted Answer

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Question 19

List several configurations that characterize different viral chromosomes.

Accepted Answer

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Question 20

In instances in the eukaryotic genome, DNA sequences represent evolutionary vestiges of duplicated copies of genes. What are such regions called and what are their characteristics?

Accepted Answer

The answer of In instances in the eukaryotic genome, DNA...

Quiz 12: DNA Organization in Chromosomes