Question 1

What similarities do bacterial chromosomes have with eukaryotic chromosomes?

Accepted Answer

Both have double-stranded DNA and several types of proteins associated with that DNA (nucleosomes in eukaryotes and HU and H1 proteins in bacteria).

Question 2

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

This category is called moderately repetitive DNA and it includes SINEs (short interspersed elements), LINEs (long interspersed elements), and VNTRs (variable number tandem repeats).

Question 3

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, a class of proteins that participate in the organization of DNA in the nucleus.

Question 4

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

Accepted Answer

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Question 5

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 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 description matches the characteristics of alphoid DNA, which is found in the centromere region and consists of tandem arrays of 170-base-pair sequences. Telomeres are found at the ends of chromosomes, primers are short pieces of DNA used in DNA synthesis, euchromatic regions are areas of chromosomes that are loosely packed and actively transcribed, and telomere-associated sequences are also found at the ends of chromosomes.

Question 7

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

Accepted Answer

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Question 8

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

Accepted Answer

E.coli has a circular, double-stranded DNA as its genetic material. RNA and proteins are also present, but they are not the main genetic material of the bacteria. Double-stranded RNA and polypeptide chains are not present as the genetic material in E.coli.

Question 9

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

Accepted Answer

Eukaryotic chromosomes contain heterochromatin and euchromatin domains that represent condensed and non-condensed regions, respectively. These regions differ in their level of gene expression and accessibility to transcription factors.

Question 10

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

Accepted Answer

Viral chromosomes can be made up of DNA or RNA, but not necessarily both. They do not typically contain significant amounts of protein or lipid-coding sequences.

Question 11

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 large amounts of non-coding DNA, and variability in genome size, is more common in eukaryotes than in prokaryotes. Prokaryotic genomes are generally smaller and more compact, with very little non-coding DNA. Within eukaryotes, there can be significant variability in genome size even among closely related species, whereas prokaryotes tend to have relatively similar genome sizes.

Question 12

What are minisatellites and microsatellites?

Accepted Answer

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Question 13

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

Accepted Answer

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Question 14

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 15

Describe the chromosomal conformations of φX174 and polyomaviruses.

Accepted Answer

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Question 16

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

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Question 17

List several configurations that characterize different viral chromosomes.

Accepted Answer

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Question 18

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

Accepted Answer

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Question 19

List the components of a nucleosome.

Accepted Answer

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Question 20

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...

Quiz 12: DNA Organization in Chromosomes