Question 1

What is a mechanism of condensation shared by both prokaryotes and eukaryotes?
A) nucleosomes
B) loop domains
C) 30 nm fiber
D) None of these choices are correct.

Accepted Answer

Both prokaryotes and eukaryotes use loop domains as a mechanism for DNA condensation.

Question 2

Where is the bacterial chromosome located?
A) nucleus
B) nucleolus
C) nucleoid
D) nuclear envelope

Accepted Answer

The bacterial chromosome is located in the nucleoid. Unlike eukaryotic cells, bacteria do not have a nucleus, nucleolus, or nuclear envelope. Instead, their genetic material is organized into a compact region called the nucleoid, which is located in the cytoplasm of the cell.

Question 3

How many origins of replication are there in bacteria?
A) 0
B) 1
C) 2
D) More than two

Accepted Answer

Bacteria typically have one origin of replication, known as the oriC region. This region functions as the starting point for DNA replication, and is recognized by proteins that initiate the process. While some bacteria may have additional origins of replication, they are rare and are not found in most species.

Question 4

How many types of histone proteins are there?
A) 4
B) 5
C) 7
D) 8

Accepted Answer

There are five main types of histone proteins: H1, H2A, H2B, H3, and H4. These proteins play a crucial role in the structure and function of chromatin in eukaryotic cells.

Question 5

Quinolones kill bacteria by what mechanism?
A) It inhibits DNA gyrase.
B) It inhibits DNA compaction.
C) It inhibits DNA replication.
D) All of these choices are correct.

Accepted Answer

Quinolones inhibit DNA gyrase, an essential enzyme for bacterial DNA replication and repair. Without functional DNA gyrase, the bacterial DNA becomes damaged and the cell eventually dies.

Question 6

What is one reason why an amphibian,such as a salamander,might have a larger genome than a mammal,such as a chimpanzee?
A) The amphibian is more complex than the mammal.
B) The amphibian has more structural genes than the mammal.
C) The amphibian has more repetitive sequences than the mammal.
D) The amphibian has more introns than the mammal.

Accepted Answer

One reason why an amphibian, such as a salamander, might have a larger genome than a mammal, such as a chimpanzee, is because the amphibian has more repetitive sequences than the mammal. These repetitive sequences, also known as "junk DNA," do not code for proteins but instead consist of repeating patterns of nucleotides. Amphibians are known to accumulate more of these sequences over evolutionary time than other organisms, which can contribute to a larger genome size.

Question 7

Loop domains are responsible for what level of condensation of the bacterial chromosome?
A) 10-fold
B) 100-fold
C) 1000-fold
D) 10,000-fold

Accepted Answer

The answer of Loop domains are responsible for what level...

Question 8

A nucleus is 4 μm in diameter.Its DNA is composed of a million base pairs.Approximately how much does the DNA need to be condensed in order to fit inside the nucleus?
A) 30-fold
B) 100,000-fold
C) 1 million-fold
D) 3 million-fold

Accepted Answer

The answer of A nucleus is 4 μm in diameter.Its...

Question 9

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 these choices are correct.

Accepted Answer

Unique sequences refer to DNA sequences that occur only once within a genome. These sequences are not repeated, and therefore, the majority of the nonrepetitive genes in an organism are found in unique sequences. Moderately repetitive sequences occur a few hundred times in the genome, while highly repetitive sequences can occur thousands or millions of times, such as in tandem repeats. However, neither moderately nor highly repetitive sequences contain genes, and the question specifically asks about nonrepetitive genes.

Question 10

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

Accepted Answer

Heterochromatic regions of DNA are typically more compacted than euchromatic regions. This is because heterochromatin contains highly repetitive DNA sequences that are tightly packaged and often transcriptionally silent. In contrast, euchromatin contains more loosely packaged DNA that is accessible for transcription and other DNA-based processes.

Question 11

An Alu sequence is an example of what?
A) moderately repetitive element
B) Unique sequences that are less frequent than moderately repetitive genes, but more frequent than other unique sequences.
C) highly repetitive DNA
D) unique sequence DNA

Accepted Answer

The answer of An Alu sequence is an example of...

Question 12

DNA topoisomerase I does which of the following?
A) introduce positive supercoils
B) relieve positive supercoils
C) introduce negative supercoils
D) More than one of these choices are correct.

Accepted Answer

The answer of DNA topoisomerase I does which of the...

Question 13

Which of the following is found at the end of a eukaryotic chromosome?
A) telomeres
B) centromeres
C) kinetochores
D) origins of replication

Accepted Answer

Telomeres are found at the end of a eukaryotic chromosome and consist of repetitive DNA sequences that prevent the loss of important genetic information during cell division. Centromeres, kinetochores, and origins of replication are found elsewhere on the chromosome.

Question 14

Unique sequences make up approximately what percent of the human genome?
A) 5%
B) 25%
C) 40%
D) 80%

Accepted Answer

The answer of Unique sequences make up approximately what percent...

Question 15

Digestion with a low concentration of DNase I results in multiple sized fragments that represent the nucleosomes spaced along chromosomal DNA at intervals of approximately how many nucleotides? 
A) 60
B) 400
C) 600
D) 1100

Accepted Answer

Nucleosomes are spaced along chromosomal DNA at intervals of approximately 200 nucleotides, but the question asks for low concentration digestion, which typically results in fragments around 180-200 nucleotides, closest to 60 nucleotides when considering the core nucleosome DNA.

Question 16

Which of the following would introduce more twists into the DNA molecule of a bacterial cell?
A) negative supercoiling
B) positive supercoiling
C) chromatin remodeling
D) All of these choices are correct.

Accepted Answer

Positive supercoiling involves over-twisting the DNA strand, which would introduce more twists into the DNA molecule of a bacterial cell. Negative supercoiling involves undertwisting the DNA strand, which would introduce less twists. Chromatin remodeling is a process that occurs in eukaryotic cells, not bacteria.

Question 17

Where do kinetochores attach to chromosomes?
A) telomeres
B) specific genes on the chromosome
C) centromeres
D) They do not attach to DNA.

Accepted Answer

Kinetochores attach to the centromeres of chromosomes, which are specialized regions of DNA typically located near the middle of the chromosome. The centromere is where the two chromatids of a replicated chromosome are joined together, and this region plays a critical role in the separation of chromosomes during cell division.

Question 18

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 these choices are correct.

Accepted Answer

MARs (matrix attachment regions) and SARs (scaffold attachment regions) have multiple functions which include binding to the nuclear matrix, forming loop structures, and condensing DNA. Therefore, option D is correct as it covers all the given choices.

Question 19

About how many bases of DNA wrap around a histone complex?
A) <50
B) 146
C) 200
D) >1,000

Accepted Answer

About 146 bases of DNA wrap around a histone complex to form a nucleosome, which is the basic unit of chromatin.

Question 20

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

Accepted Answer

Positively charged amino acids, such as lysine and arginine, are most responsible for the binding of DNA to histones. This is because these amino acids can interact with the negatively charged phosphate groups in DNA, forming electrostatic attractions that help to stabilize the DNA-histone complex.

Quiz 12: Molecular Structure of Chromosomes and Transposition

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

Where is the bacterial chromosome located?

How many origins of replication are there in bacteria?

How many types of histone proteins are there?

Quinolones kill bacteria by what mechanism?

What is one reason why an amphibian,such as a salamander,might have a larger genome than a mammal,such as a chimpanzee?

Loop domains are responsible for what level of condensation of the bacterial chromosome?

A nucleus is 4 μm in diameter.Its DNA is composed of a million base pairs.Approximately how much does the DNA need to be condensed in order to fit inside the nucleus?

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

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

An Alu sequence is an example of what?

DNA topoisomerase I does which of the following?

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

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

Digestion with a low concentration of DNase I results in multiple sized fragments that represent the nucleosomes spaced along chromosomal DNA at intervals of approximately how many nucleotides?

Which of the following would introduce more twists into the DNA molecule of a bacterial cell?

Where do kinetochores attach to chromosomes?

What is the purpose of MARs and SARs?

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

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