Question 1

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus)and bacterial cells.In this experiment,how is transformation (altered phenotype)displayed?
A)The bacteria are transformed (by phage DNA)into virus synthesizing cells.
B)The bacteria are transformed from live to dead by the virus.
C)The bacteria are transformed from rough to smooth by the virus.
D)The bacteria are transformed into a virus.
E)Transformation is not exhibited by a virus-infected bacterial cell.

Accepted Answer

The Hershey-Chase experiment demonstrated that DNA, not protein, is the genetic material of phage viruses, which transform bacteria by injecting their DNA, causing the bacteria to produce more viruses.

Question 2

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus)and bacterial cells.In these experiments,they used radioactivity to label nucleic acids (in this case DNA)and proteins.What do radioactive sulfur and phosphate specifically label?
A)Sulfur labels DNA,and phosphate labels protein.
B)Sulfur labels both protein and DNA.
C)Phosphate labels both protein and DNA.
D)Sulfur labels protein,and phosphate labels DNA.
E)None of the answer options are correct.

Accepted Answer

Radioactive sulfur specifically labels proteins while radioactive phosphate specifically labels nucleic acids such as DNA. Therefore, sulfur would label any proteins present in the bacteriophage, while phosphate would label the DNA in the bacteriophage.

Question 3

Chargaff's rules do NOT hold for which of the following genome types?
A)yeast
B)bacteria
C)single-stranded DNA virus
D)invertebrates
E)Archaeobacteria

Accepted Answer

Chargaff's rules state that in any DNA molecule, the amount of adenine (A) is equal to thymine (T) and the amount of guanine (G) is equal to cytosine (C). This holds true for most genome types, including yeast, bacteria, invertebrates, and archaeobacteria. However, single-stranded DNA viruses do not follow this rule as they often have a skewed base composition with a higher amount of certain bases than others.

Question 4

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus)and bacterial cells.If phage are labeled with radioactive sulfur and allowed to infect bacterial cells,the radioactive sulfur will be localized to:
A)the inside of infected cells (in phage DNA).
B)the outside of infected cells (in phage ghosts).
C)in newly synthesized phage viruses in the host bacterial cell.
D)No radioactivity will remain after infection.
E)The sulfur will be metabolically consumed,and therefore the radioactivity will be destroyed.

Accepted Answer

When the phage are labeled with radioactive sulfur, the radioactivity will be localized to the outside of infected bacterial cells (in phage ghosts) as the phage protein coat contains sulfur but the bacterial cells do not. Therefore, option B is the correct choice. The other options are not valid because the radioactive sulfur will either be inside the phage or will be destroyed/metabolized during infection.

Question 5

Based on its association with chromosomes,this was once considered the hereditary molecule before the discovery of DNA.
A)phospholipids
B)proteins
C)glycogen
D)cholesterol
E)None of the answer options are correct.

Accepted Answer

Before the discovery of DNA, it was believed that genes were made up of proteins because they were the predominant substance found in chromosomes. However, it was later discovered that DNA is the genetic material and carries the hereditary information.

Question 6

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus)and bacterial cells.If phage are labeled with radioactive phosphate and allowed to infect bacterial cells,the radioactive phosphate will be localized to:
A)the inside of infected cells (in phage DNA).
B)the outside of infected cells (in phage ghosts).
C)newly synthesized phage viruses in the host bacterial cell.
D)No radioactivity will remain after infection.
E)The phosphate will be metabolically consumed,and therefore the radioactivity will be destroyed.

Accepted Answer

Radioactive phosphate will be incorporated into the phage DNA, which will be located inside the infected bacterial cells.

Question 7

Which statement below best describes the situation between nucleotides on opposite strands in a DNA molecule?
A)A-T and C-G bonding between opposite strands involves two hydrogen bonds for either pair.
B)A-T and C-G bonding between opposite strands involves three hydrogen bonds for either pair.
C)A-T bonding between opposite strands involves two hydrogen bonds,whereas G-C bonding between strands involves three hydrogen bonds.
D)A-T bonding between opposite strands involves three hydrogen bonds,whereas G-C bonding between strands involves two hydrogen bonds.

Accepted Answer

A-T bonding between opposite strands involves two hydrogen bonds, whereas G-C bonding between strands involves three hydrogen bonds.

Question 8

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus)and bacterial cells.Sulfur was used to label cellular components in this experiment because of its presence in the amino acid(s):
A)histidine.
B)methionine and cysteine.
C)tyrosine.
D)glycine.
E)serine.

Accepted Answer

Methionine and cysteine are the amino acids that contain sulfur. By labeling the viral proteins with radioactive sulfur, Hershey and Chase were able to determine that viral DNA, and not protein, was the genetic material responsible for transformation in bacteria.

Question 9

Evidence of transformation of R strain cells by biomolecules from S strain cells includes:
A)the R strain cells begin to produce high levels of neurotoxin.
B)the transformed R strain cells gain the ability to kill mice.
C)isolation of smooth-looking cells from animals infected with R strain cells that had been incubated with heat-killed S strain cells.
D)the R strain cells produce neurotoxin and gain the ability to kill mice
E)the R strain cells gain the ability to kill mice,and smooth-looking cells were isolated from animals infected with R strain cells previously incubated with heat-killed S strain cells.

Accepted Answer

The answer of Evidence of transformation of R strain cells...

Question 10

Of the three key building blocks of DNA,which type(s)of building block stabilizes the structure via weak van der Waals interactions (through stacking)and regular hydrogen bonds?
A)phosphate
B)deoxyribose
C)nitrogenous bases
D)both phosphate and nitrogenous bases
E)All of the answer options are correct.

Accepted Answer

The nitrogenous bases stabilize the structure of DNA via weak van der Waals interactions through stacking and regular hydrogen bonds. Phosphate groups provide a negative charge and help to form the backbone of DNA, while deoxyribose sugars connect the individual nucleotides.

Question 11

Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design.The key difference was:
A)purifying S strain DNA and RNA from other biomolecules.
B)systematically eliminating the impact of classes of S strain biomolecules using enzymatic digestion before mixing with R strain live cells.
C)injecting S strain DNA directly into R strain cells and observing the change in phenotype.
D)Avery used Escherichia coli rather than Streptococcus as it is easier to transform.
E)All of the answer options are correct.

Accepted Answer

Avery and his colleagues systematically eliminated the impact of classes of S strain biomolecules using enzymatic digestion before mixing with R strain live cells. This allowed them to determine that DNA was the transforming factor.

Question 12

Mendel identified evidence for the location of genes on separate structures (chromosomes)through his:
A)electrophoresis experiments.
B)purification of chromosomes from pea plants.
C)identification of dominant and recessive alleles of genes.
D)identification of independent assortment of distinct genes during meiosis.
E)use of high resolution microscopic techniques.

Accepted Answer

Mendel identified the independent assortment of distinct genes during meiosis, which provided evidence for the location of genes on separate structures, later known as chromosomes. This was a crucial discovery for the field of genetics, as it laid the foundation for the understanding of the physical basis of inheritance. However, the other options listed were not directly related to Mendel's discovery of the location of genes on chromosomes.

Question 13

Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design.They found that the enzyme ______________ was effective at destroying the transforming capacity of S strain biomolecules.
A)protease (protein destruction)
B)RNase (RNA destruction)
C)DNase (DNA destruction)
D)polysaccharide-destroying enzymes
E)lipase (lipid destruction)

Accepted Answer

Avery and colleagues used DNase, an enzyme that specifically breaks down DNA, to show that the transforming factor present in the S strain bacteria was indeed DNA. If the transforming ability was destroyed by DNase, but not by other enzymes such as protease or RNase, it meant that DNA was the key component responsible for transformation.

Question 14

Smooth (S)and rough (R)strains of Streptococcus pneumonia are distinct because of their ability to cause illness (death in rodents).This trait is controlled by genes that regulate:
A)the production of a protective polysaccharide coat (capsule)around each cell.
B)the production of lethal toxins.
C)the speed of bacterial growth.
D)the metabolic rate of microbial glycolysis.
E)the bacterial ability to penetrate through the membrane of animal cells.

Accepted Answer

The ability to cause illness (death in rodents) in S. pneumonia is controlled by genes that regulate the production of a protective polysaccharide coat (capsule) around each cell. The smooth strains have a thick capsule that protects them from phagocytosis by immune cells, whereas rough strains lack a capsule and are more easily phagocytosed.

Question 15

What structural feature of DNA suggests a possible method of its replication?
A)The nucleotides between nucleotide strands are complementarily paired.
B)The hydrogen bonds between A-T and G-C are the same on all DNA molecules.
C)The DNA strands run anti-parallel.
D)The phosphate bonds in the backbone of all DNA molecules.

Accepted Answer

The complementary pairing of nucleotides (A with T and G with C) suggests a method of replication where each strand serves as a template for the formation of a new complementary strand.

Question 16

Of the three key building blocks of DNA,which type(s)of building block is/are structurally different in RNA molecules?
A)phosphate
B)deoxyribose
C)nitrogenous bases
D)both deoxyribose and nitrogenous bases
E)All of the answer options are correct.

Accepted Answer

RNA contains ribose instead of deoxyribose and uracil instead of thymine as a nitrogenous base, making both deoxyribose and nitrogenous bases structurally different in RNA compared to DNA.

Question 17

Which statement best describes the arrangement of components in a DNA molecule?
A)Nucleotides are located toward the outside of the strands and phosphates toward the interior.
B)Nucleotides are located toward the inside of the strands and the phosphates toward the outside.
C)Nucleotides,as well as the phosphates,are located toward the inside of the strands.
D)Nucleotides,as well as the phosphates,are located toward the outside of the strands.

Accepted Answer

The arrangement of components in a DNA molecule is such that the nucleotides (which consist of a sugar molecule, a nitrogenous base, and a phosphate group) are located toward the inside of the strands, while the phosphate groups are toward the outside. This creates a backbone of alternating sugar and phosphate molecules on the outside, with pairs of nitrogenous bases (which form the "rungs" of the DNA ladder) connecting the two strands in the middle.

Question 18

In the classic experiment by Griffith,evidence of the action of a hereditary biomolecule was identified by:
A)growth of the bacterial cells.
B)transformation (phenotypic change)of the R strain by S strain biomolecules.
C)rapid death of mice following injection with bacteria.
D)isolation of pure DNA from the S strain cells.
E)the ability of heat to destroy deadly biomolecules.

Accepted Answer

In the classic experiment by Griffith, evidence of the action of a hereditary biomolecule was identified by transformation (phenotypic change) of the R strain by S strain biomolecules. When heat-killed S strain bacteria were mixed with live R strain bacteria, the R strain bacteria were transformed into the S strain phenotype. This transformation was due to the uptake of genetic material (DNA) from the dead S strain bacteria by the live R strain bacteria. This experiment provided the first evidence for the role of DNA as the hereditary material.

Question 19

Of the three key building blocks of DNA,which type(s)of building block is/are negatively charged and oriented on the outside of the double helical structure?
A)phosphate
B)deoxyribose
C)nitrogenous bases
D)both phosphate and nitrogenous bases
E)All of the answer options are correct.

Accepted Answer

Phosphate groups are negatively charged and located on the outside of the double helix, while deoxyribose and nitrogenous bases are oriented on the inside.

Question 20

Which of the following is/are NOT a key structural property displayed by the heritable (transforming)material?
A)The structure must contain complex information (genetic code).
B)The structure must be composed of rare/unusual elements.
C)The structure must allow or tolerate small changes that facilitate nonlethal variation.
D)The structure must be enzymatically active,able to mediate cellular metabolism.
E)The structure must be composed of rare/unusual elements and must be enzymatically active,able to mediate cellular metabolism.

Accepted Answer

The answer of Which of the following is/are NOT a...

Quiz 7: Dna: Structure and Replication

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells.In this experiment,how is transformation (altered phenotype) displayed?

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells.In these experiments,they used radioactivity to label nucleic acids (in this case DNA) and proteins.What do radioactive sulfur and phosphate specifically label?

Chargaff's rules do NOT hold for which of the following genome types?

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells.If phage are labeled with radioactive sulfur and allowed to infect bacterial cells,the radioactive sulfur will be localized to:

Based on its association with chromosomes,this was once considered the hereditary molecule before the discovery of DNA.

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells.If phage are labeled with radioactive phosphate and allowed to infect bacterial cells,the radioactive phosphate will be localized to:

Which statement below best describes the situation between nucleotides on opposite strands in a DNA molecule?

Alfred Hershey and Martha Chase examined transformation using bacteriophage (bacterial DNA virus) and bacterial cells.Sulfur was used to label cellular components in this experiment because of its presence in the amino acid(s) :

Evidence of transformation of R strain cells by biomolecules from S strain cells includes:

Of the three key building blocks of DNA,which type(s) of building block stabilizes the structure via weak van der Waals interactions (through stacking) and regular hydrogen bonds?

Oswald Avery and colleagues strengthened scientific support that DNA was the transforming factor by replicating the Griffith experiment with some important differences in experimental design.The key difference was:

Mendel identified evidence for the location of genes on separate structures (chromosomes) through his:

Smooth (S) and rough (R) strains of Streptococcus pneumonia are distinct because of their ability to cause illness (death in rodents) .This trait is controlled by genes that regulate:

What structural feature of DNA suggests a possible method of its replication?

Of the three key building blocks of DNA,which type(s) of building block is/are structurally different in RNA molecules?

Which statement best describes the arrangement of components in a DNA molecule?

In the classic experiment by Griffith,evidence of the action of a hereditary biomolecule was identified by:

Of the three key building blocks of DNA,which type(s) of building block is/are negatively charged and oriented on the outside of the double helical structure?

Which of the following is/are NOT a key structural property displayed by the heritable (transforming) material?