Deck 10: Chromosome Organization and Molecular Structure

Question 1

The majority of the nonrepetitive genes in an organism are found in which of the following?

A) Unique sequences
B) Moderately repetitive sequences
C) Highly repetitive sequences
D) None of the answers are correct

Answer 1

A

Question 2

Turning the DNA helix to the right causes

A) positive supercoiling.
B) overwinding.
C) All of the answers are correct.

Answer 2

C

Question 3

Digesting chromatin with a high concentration of DNAse I would yield fragments of what approximate size?

A) 200
B) 400
C) 600
D) 1100

Answer 3

A

Question 4

What types of amino acids are most responsible for the binding of DNA to histones?

A) Hydrophobic amino acids
B) Polar amino acids
C) Positively charged amino acids
D) Negatively charged amino acids

Question 5

What is a mechanism of condensation shared by both prokaryotes and eukaryotes?

A) Nucleosomes
B) Loop domains
C) 30 nm fiber
D) None of the answers are correct

Question 6

Chemicals such as quinolones are antibacterial. How does it kill bacteria?

A) It inhibits DNA gyrase.
B) It inhibits DNA compaction.
C) It inhibits DNA replication.
D) All of the answers are correct.

Question 7

Unique sequences make up approximately what percent of the human genome?

A) 5%
B) 25%
C) 40%
D) 80%

Question 8

Which of the following is found at the end of a eukaryotic chromosome?

A) Telomeres
B) Centromeres
C) Kinetochores
D) Origins of replication

Question 9

How many origins of replication are there in bacteria?

A) 0
B) 1
C) 2
D) More than two

Question 10

DNA topoisomerase I does which of the following?

A) Relax negative supercoils
B) Relax positive supercoils
C) Introduce negative supercoils
D) More than one of the answers are correct

Question 11

An Alu sequence is an example of what?

A) Retroelement
B) Transposable element
C) Highly repetitive DNA
D) All of the answers are correct

Question 12

What is the purpose of MARs and SARs?

A) To bind to the nuclear matrix
B) To form loop structure
C) To condense DNA
D) All of the answers are correct

Question 13

Where is the bacterial chromosome located?

A) Nucleus
B) Nucleolus
C) Nucleoid
D) Nuclear envelope

Question 14

One would expect heterochromatic regions of DNA to be more compacted than euchromatic regions.

Question 15

About how many bases of DNA wrap around a histone complex?

A) < 50
B) 150
C) 200
D) > 1,000

Question 16

Where do kinetochores attach to chromosomes?

A) Telomeres
B) Specific genes on the chromosome
C) Centromeres
D) They don't attach to DNA

Question 17

Loop domains in prokaryotes involve how many base pairs?

A) 10,000
B) 100,000
C) 1000
D) 50,000

Question 18

Negative Supercoiling in bacteria

A) makes the chromosomal DNA more compact.
B) creates tension because of the underwinding of the DNA.
C) can promote DNA strand separations in small regions.
D) All of the answers are correct.

Question 19

Why do amphibians have so much more DNA than humans?

A) Amphibians have more repetitive sequences than do humans.
B) Amphibians are more biologically complex than mammals.
C) Amphibians have more genes than do humans.
D) Amphibians are tetraploid, while humans are diploid.

Question 20

How many types of histone proteins are there?

A) 4
B) 5
C) 7
D) 8

Question 21

Over winding of the DNA decreases the number of turns in the double helix, and thus results in super coils in the DNA.

Question 22

A Barr body is an example of what?

A) Constitutive heterochromatin
B) Facultative heterochromatin
C) Constitutive euchromatin
D) Facultative euchromatin

Question 23

The term genome refers to the complete complement of sequences and genes that an organism possesses.

Question 24

A nucleosome is a combination of ________ and ________.

A) histone proteins, scaffold proteins
B) RNA, transcription proteins
C) DNA, histone proteins
D) RNA, histone proteins
E) DNA, scaffold proteins

Question 25

The origins of replication in eukaryotic chromosomes are spaced about every ________ base pairs.

A) 100,000
B) 1000
C) 100
D) 10
E) 500

Question 26

The zig-zag and solenoid models are associated with the ________ level of DNA organization.

A) histone
B) 11nm fiber
C) beads-on-a-string
D) 30 nm fiber
E) scaffold protein

Question 27

Which of the following is not a mechanism used by bacteria to condense their DNA?

A) Super coiling.
B) Packaging the DNA with histone proteins.
C) Looping of the DNA.
D) Increase or decrease the number of turns in the DNA.
E) Anchoring the DNA loops with DNA-binding proteins.

Question 28

The two processes of wrapping DNA on nucleosomes and arranging them into a 30 nm fiber shorten the DNA by how much?

A) 30-fold
B) 50 fold
C) 1 million-fold
D) 3 million-fold

Question 29

Which of the following assists the alignment of sister chromatids during metaphase?

A) Radial loop domains
B) Cohesin
C) Centromeres
D) Nucleosomes
E) Condensin

Question 30

The different DNA configurations that are generated by super coiling are called topoisomers of one another.

Question 31

The 30 nm fiber is formed from arrays of nucleosomes.

Question 32

Each radial loop domain may contain between 10 and 100 base pairs of DNA.

Question 33

Which of the following represents the highest level of chromosome condensation?

A) Radial loop domain
B) 30 nm fibers
C) Double helix
D) Nucleosome
E) Heterochromatin

Question 34

The majority of bacterial DNA is negatively super coiled.

Question 35

The function of condensin is to

A) cause the chromosomes to uncompact following mitosis.
B) coat the chromosomes and condense them into heterochromatin through the compaction of radial loops.
C) hold the DNA to the histone proteins in the nucleosome core particle.
D) trigger DNA to be compacted in a nucleosome core particle.
E) None of the answers are correct.

Question 36

Which of the following is not part of the structure of the nucleosome core particle?

A) It is composed of an octamer of proteins.
B) There is a linker region between two nucleosomes of about 200 base pairs.
C) There are two copies each of H2A, H2B, H3 and H4.
D) The DNA is wrapped around the core slightly over two complete turns.
E) The DNA wrapped around the core contains 146-147 base pairs.

Question 37

Areas of the chromosome that remain highly condensed are called ________.

A) Euchromatin
B) Facultative heterochromatin
C) Constitutive heterochromatin
D) Barr body

Question 38

Which of the following represents the lowest level of chromosome condensation?

A) Radial loop domain
B) 30 nm fibers
C) Heterochromatin
D) Nucleosome
E) Euchromatin

Question 39

The DNA of a bacterial cell must be compacted about ________ fold to fit within the confines of the cell.

A) 10-
B) 100-
C) 150-
D) 1000-
E) 1,000,000-

Question 40

Which of the following is correctly matched with its description?

A) Highly repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies.
B) Moderately repetitive DNA contains unique sequences, such as genes found in one or a few copies.
C) Nonrepetitive DNA is composed of thousands of copies of many short repeats.
D) Moderately repetitive DNA contains retro elements, such as the Alu sequence.
E) Moderately repetitive DNA contains transposable elements and genes that are expressed in abundance and thus have many copies.

Question 41

The is a strong relationship between organism complexity and genome size in eukaryotes

Question 42

Why do positively charged amino acids appear more often than usual in histone proteins?

A) Histones have a higher molecular mass, which improves DNA compaction.
B) Histones are strongly attracted to the positively charged phosphate backbone of DNA.
C) Histones and DNA have opposite charges, which improves the compaction of DNA into nucleosomes.
D) Histones and DNA have the same charge, which improves the compaction of DNA into nucleosomes.

Question 43

The DNA-protein complex in eukaryotic chromosomes is called the genome.

Question 44

Because of entropy, chromosomes overlap in an interphase nucleus in a random way