Question 1

A single DNA molecule contains two specific target sites separated by an intervening sequence.If site-specific recombination between these sites causes the intervening sequence to be released as a separate circular DNA molecule containing one target site, then the sites were oriented in

Accepted Answer

When two target sites are oriented in the same direction on a DNA molecule, site-specific recombination can lead to the excision of the intervening sequence as a separate circular DNA molecule.

Question 2

A virus that infects bacterial cells is known as a

Accepted Answer

Bacteriophages are viruses that specifically infect and replicate within bacteria.

Question 3

With respect to DNA structure, polarity means that

Accepted Answer

DNA strands have a 5′ to 3′ directionality, which refers to the orientation of the nucleotides in a strand of DNA or RNA. The 5′ end has a phosphate group attached to the fifth carbon atom of the sugar ring, and the 3′ end has a hydroxyl group attached to the third carbon atom of the sugar ring. This directionality is crucial for processes such as DNA replication and transcription.

Question 4

Crossing-over that occurs only between two specific DNA target sites that are usually less than 200 base pairs long is called

Accepted Answer

Site-specific recombination involves the exchange of genetic material between two specific DNA sites, often facilitated by specific enzymes that recognize these unique sequences. This process can occur in both prokaryotic and eukaryotic organisms and is crucial for various biological functions, including the integration of viral DNA into host genomes and the regulation of gene expression.

Question 5

Exposure of which of the following regions of a molecule of DNA permits the reading of DNA sequence without opening the double helix?

Accepted Answer

The major groove of DNA provides the necessary access for proteins to read the genetic information without the need to open the double helix. This region is wider and more accessible for protein binding, allowing for the recognition of specific DNA sequences.

Question 6

Suppose that in the future, scientists identify bacteria on Mars and these organisms lack a site-specific recombination system.Which components would allow for site-specific recombination to occur in these bacteria?

Accepted Answer

Site-specific recombination requires specific sequences where recombination occurs and an enzyme that catalyzes the recombination process. FRT target sites and Flp recombinase work together in the Flp-FRT recombination system to enable site-specific recombination.

Question 7

Which protein is needed to lay down a segment of RNA complementary to the DNA before replication can begin?

Accepted Answer

Primase is the enzyme responsible for synthesizing a short RNA primer, which serves as a starting point for DNA polymerase to begin DNA replication. This RNA segment is complementary to the DNA strand.

Question 8

Suppose a region of DNA is 100 bp long.How many unique sequences could it potentially represent?

Accepted Answer

Each base pair in DNA can be one of four nucleotides (adenine, thymine, cytosine, or guanine), so for each position in a 100 bp long sequence, there are 4 choices. The total number of unique sequences is therefore $4^{100}$.

Question 9

Which protein relaxes supercoils by nicking the DNA?

Accepted Answer

Topoisomerase relaxes supercoils by creating temporary nicks in the DNA molecule, allowing it to unwind and relieve tension before resealing the breaks.

Question 10

Which of the following properties of RNA is most directly responsible for its ability to form complex shapes?

Accepted Answer

RNA's ability to form complex shapes is primarily due to it being single-stranded, which allows it to fold into various structures through intramolecular base pairing.

Question 11

Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal ¹⁴N medium.You then grew the cells for 3 generations in medium containing ¹⁵N.The outcome would be

Accepted Answer

The answer of Suppose the experiment of Meselson and Stahl...

Question 12

If you repeated the Hershey and Chase experiment designed to determine the molecule of heredity using a virus with RNA as its genetic material, you would expect that

Accepted Answer

The Hershey and Chase experiment originally used bacteriophages with DNA as their genetic material and demonstrated that DNA, not protein, was the molecule transferred to bacteria. If the experiment were repeated with a virus that has RNA as its genetic material, the equivalent result would show that RNA is transferred to the infected cells, hence option C is correct.

Question 13

Which type of virus causes polio and AIDS?

Accepted Answer

Polio is caused by a virus known as poliovirus, which is not listed among the options given. However, AIDS is caused by the Human Immunodeficiency Virus (HIV), which is a type of retrovirus. Therefore, the correct answer is retrovirus (A) for AIDS, but none of the options correctly identifies the virus type for polio.

Question 14

Given the following strand of DNA: 5′ CATAGCCTTA 3′
Which of the following sequences is the complementary DNA strand?

Accepted Answer

The complementary DNA strand is formed by pairing A with T and G with C, but it is also antiparallel to the original strand. Therefore, the correct complementary sequence to 5′ CATAGCCTTA 3′ is 3′ GTATCGGAAT 5′.

Question 15

Z-form DNA is a ________ helix with ________ backbone.

Accepted Answer

The answer of Z-form DNA is a ________ helix with...

Question 16

Avery and colleagues purified a white substance as the transforming principle.Treating this substance with enzymes that destroyed RNA, protein, or polysaccharides did not affect its ability to transform cells, but enzyme that degrades DNA destroyed the transforming ability.These results suggested that

Accepted Answer

The experiment showed that only the enzyme that degrades DNA destroyed the transforming ability, indicating that DNA was the substance responsible for transformation.

Question 17

How many origins of replication does the E.coli chromosome contain?

Accepted Answer

The E. coli chromosome contains a single origin of replication, known as OriC, from which DNA replication is initiated.

Question 18

Which of the following is an example of a protein that can read the sequence of DNA without opening the double helix?

Accepted Answer

Transcription factors can recognize and bind to specific DNA sequences without the need for the DNA double helix to be unwound, allowing them to regulate the transcription of genes.

Question 19

Which of the following contains single-stranded DNA as its genetic material?

Accepted Answer

фX174 is a bacteriophage known for having single-stranded DNA (ssDNA) as its genetic material, unlike humans and E.coli which have double-stranded DNA, and HIV which has RNA.

Question 20

Transformation in bacteria results from the uptake of which molecule?

Accepted Answer

Transformation in bacteria involves the uptake of DNA from their surroundings, which can then be incorporated into their own genome, allowing for genetic changes.

Quiz 6: DNA Structure, Replication, and Recombination

A single DNA molecule contains two specific target sites separated by an intervening sequence.If site-specific recombination between these sites causes the intervening sequence to be released as a separate circular DNA molecule containing one target site, then the sites were oriented in

A virus that infects bacterial cells is known as a

With respect to DNA structure, polarity means that

Crossing-over that occurs only between two specific DNA target sites that are usually less than 200 base pairs long is called

Exposure of which of the following regions of a molecule of DNA permits the reading of DNA sequence without opening the double helix?

Suppose that in the future, scientists identify bacteria on Mars and these organisms lack a site-specific recombination system.Which components would allow for site-specific recombination to occur in these bacteria?

Which protein is needed to lay down a segment of RNA complementary to the DNA before replication can begin?

Suppose a region of DNA is 100 bp long.How many unique sequences could it potentially represent?

Which protein relaxes supercoils by nicking the DNA?

Which of the following properties of RNA is most directly responsible for its ability to form complex shapes?

Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal ¹⁴N medium.You then grew the cells for 3 generations in medium containing ¹⁵N.The outcome would be

If you repeated the Hershey and Chase experiment designed to determine the molecule of heredity using a virus with RNA as its genetic material, you would expect that

Which type of virus causes polio and AIDS?

Given the following strand of DNA: 5′ CATAGCCTTA 3′ Which of the following sequences is the complementary DNA strand?

Z-form DNA is a helix with backbone.

How many origins of replication does the E.coli chromosome contain?

Which of the following is an example of a protein that can read the sequence of DNA without opening the double helix?

Which of the following contains single-stranded DNA as its genetic material?

Transformation in bacteria results from the uptake of which molecule?

Quiz 6: DNA Structure, Replication, and Recombination

A single DNA molecule contains two specific target sites separated by an intervening sequence.If site-specific recombination between these sites causes the intervening sequence to be released as a separate circular DNA molecule containing one target site, then the sites were oriented in

A virus that infects bacterial cells is known as a

With respect to DNA structure, polarity means that

Crossing-over that occurs only between two specific DNA target sites that are usually less than 200 base pairs long is called

Exposure of which of the following regions of a molecule of DNA permits the reading of DNA sequence without opening the double helix?

Suppose that in the future, scientists identify bacteria on Mars and these organisms lack a site-specific recombination system.Which components would allow for site-specific recombination to occur in these bacteria?

Which protein is needed to lay down a segment of RNA complementary to the DNA before replication can begin?

Suppose a region of DNA is 100 bp long.How many unique sequences could it potentially represent?

Which protein relaxes supercoils by nicking the DNA?

Which of the following properties of RNA is most directly responsible for its ability to form complex shapes?

Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal 14N medium.You then grew the cells for 3 generations in medium containing 15N.The outcome would be

If you repeated the Hershey and Chase experiment designed to determine the molecule of heredity using a virus with RNA as its genetic material, you would expect that

Which type of virus causes polio and AIDS?

Given the following strand of DNA: 5′ CATAGCCTTA 3′ Which of the following sequences is the complementary DNA strand?

Z-form DNA is a ________ helix with ________ backbone.

How many origins of replication does the E.coli chromosome contain?

Which of the following is an example of a protein that can read the sequence of DNA without opening the double helix?

Which of the following contains single-stranded DNA as its genetic material?

Transformation in bacteria results from the uptake of which molecule?

Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal ¹⁴N medium.You then grew the cells for 3 generations in medium containing ¹⁵N.The outcome would be

Z-form DNA is a helix with backbone.