Deck 11: Chromosome Structure and DNA Sequence Organization

Question 1

What similarities do bacterial chromosomes have with eukaryotic chromosomes?

Answer 1

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

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

Answer 2

The amount of DNA per structure (virus particle,bacterium,cell)increases as one goes from viruses to eukaryotic cells.Viral chromosomes may be composed of single-stranded or double-stranded RNA or DNA,whereas bacterial and eukaryotic DNA is double-stranded.Bacterial DNA is considered to be a covalently closed circle; the "global" structure of eukaryotic chromosomes is uncertain.Although some proteins are associated with viral and bacterial DNA,the regularly spaced histones of eukaryotic chromosomes are unique.

Question 3

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

Answer 3

One base pair is 0.34 nm; therefore,51,365 bp X 0.34 nm/bp = 17,464 nm or 17.46 ?m.

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?

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.

Question 6

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

A)circular,double-stranded DNA
B)linear,double-stranded DNA
C)RNA and protein
D)circular,double-stranded RNA
E)polypeptide chains

Question 7

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

Question 8

Describe the chromosomal conformations of ?X174 and polyoma viruses.

Question 9

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?

Question 10

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

A)composite DNA; telomeres and heterochromatin
B)dominant DNA; euchromatin and heterochromatin
C)multiple gene family DNA; hemoglobin and 5.0S RNA
D)moderately repetitive DNA; SINEs,LINEs,and VNTRs
E)permissive DNA; centromeres and heterochromatin

Question 11

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

Question 12

List the components of a nucleosome.

Question 13

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

Question 14

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

A)histones
B)glycoproteins
C)lipids
D)H1 histones
E)nonhistone chromosomal proteins

Question 15

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

A)called heterochromatin and euchromatin
B)uniform in the genetic information they contain
C)separated by large stretches of repetitive DNA
D)each void of typical protein-coding sequences of DNA
E)void of introns

Question 16

List several configurations that characterize different viral chromosomes.

Question 17

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 ________.

A)telomeres
B)primers
C)alphoid families
D)euchromatic regions
E)telomere-associated sequences

Question 18

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

A)protein- or lipid-coding sequences
B)DNA only
C)DNA or RNA
D)RNA only
E)DNA,RNA,or protein

Question 19

What are minisatellites and microsatellites?

Question 20

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 ________.

A)viruses than in bacteria
B)RNA viruses than in DNA viruses
C)eukaryotes than in prokaryotes
D)the alphoid rather than the diphloid family
E)prokaryotes than in eukaryotes

Question 21

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

Question 22

In the formation of nucleosomes,one histone class,H1,is not directly involved,yet it does associate with DNA to form higher-level chromosomal structures.Where does this histone (H1)associate?

Question 23

In contrast with euchromatin,heterochromatin contains more genes and is earlier replicating.

Question 24

In situ hybridization allows one to "visualize" the location of labeled RNA or DNA in a tissue or cell.

Question 25

Briefly state what is meant by repetitive DNA.

Question 26

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

Question 27

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

Question 28

The E.coli chromosome is circular and double-stranded DNA.

Question 29

What is meant by SINE in terms of chromosome structure? by LINE? Why are they called "repetitive"?

Question 30

Viral genomes are always linear,double-stranded DNA.

Question 31

What is the function of a TERRA (telomere repeat-containing RNA)?

Question 32

Telomerase is an enzyme involved in the replication of the ends of eukaryotic chromosomes.

Question 33

Each human contains an identical set of VNTRs.

Question 34

How do VNTRs relate to DNA fingerprinting?