Question 1

DNA primase

Accepted Answer

DNA primase synthesizes a short RNA primer that is complementary to a DNA template, which is necessary for DNA polymerase to initiate DNA replication.

Question 2

Based on their experiment with T2 bacteriophages,Hershey and Chase concluded that

Accepted Answer

Hershey and Chase concluded that DNA, not protein, functions as the genetic material based on their experiment with T2 bacteriophages. They labeled either the DNA or protein of the phage and found that only the labeled DNA was transferred into the infected bacteria, leading to the production of new phages. This supported the idea that DNA is the genetic material responsible for controlling the traits of an organism.

Question 3

The synthesis of a growing strand of DNA is carried out by adding nucleotides to the ________ end of an existing strand.

Accepted Answer

DNA polymerases add nucleotides to the 3' end of the growing strand, ensuring directionality of synthesis from 5' to 3'.

Question 4

Which is not a component of nucleic acids?

Accepted Answer

Sulfur is not a component of nucleic acids, while organic nitrogenous base, pentose sugar, and phosphate are all essential components.

Question 5

When a mixture of live nonvirulent bacteria and dead virulent bacteria was injected into mice,Griffith unexpectedly found that the injected mice died.He explained this result by suggesting that the nonvirulent bacteria are being

Accepted Answer

Griffith's observation that the mixture of live nonvirulent bacteria and dead virulent bacteria resulted in the death of the mice suggests that something transformed the nonvirulent bacteria into a virulent form. This phenomenon became known as transformation, and it led to the discovery of DNA as the genetic material.

Question 6

The chemical bond connecting one nucleotide with the next along one strand of a DNA molecule is called a

Accepted Answer

The chemical bond connecting one nucleotide with the next along one strand of a DNA molecule is a phosphodiester bond. This bond is formed between the phosphate group of one nucleotide and the sugar (ribose or deoxyribose) of the next nucleotide, linking them together to form the sugar-phosphate backbone of the DNA strand. The nitrogenous bases protrude from this backbone and form hydrogen bonds with complementary bases on the opposing strand to form the double helix structure of DNA.

Question 7

As the two strands of DNA are unraveled,which enzyme relieves the strain on the two strands?

Accepted Answer

DNA gyrase relieves the strain on the two strands of DNA by introducing negative supercoils ahead of the replication fork.

Question 8

Who originally discovered the process of bacterial transformation?

Accepted Answer

The process of bacterial transformation was first discovered by Frederick Griffith in 1928 while studying the Streptococcus pneumoniae bacterium.

Question 9

Because the two strands of a DNA molecule are ________ to each other,either one can be used as a template to reconstruct the other.

Accepted Answer

The statement says that the two strands of a DNA molecule are complementary to each other, which means that the bases on one strand pair specifically with the bases on the other strand (A with T, and C with G). This complementarity allows either strand to be used as a template to reconstruct the other during DNA replication or transcription.

Question 10

After attaching to a bacterial cell,a bacteriophage typically

Accepted Answer

Bacteriophages inject their DNA into bacterial cells in order to take over the cell's machinery and replicate themselves. This process is essential to the phage life cycle and allows them to spread and infect other bacterial cells.

Question 11

The method of DNA replication,where each original strand is used as a template to build a new strand,is called the

Accepted Answer

The method of DNA replication where each original strand is used as a template to build a new strand is called semiconservative method. This is because each new double-stranded DNA molecule consists of one strand from the original DNA molecule and one newly synthesized strand.

Question 12

________ is the genetic material for all cellular organisms and some viruses.

Accepted Answer

DNA is the genetic material for all cellular organisms and some viruses. RNA is a nucleic acid that plays a role in protein synthesis but is not necessarily the genetic material. Protein and chromatin are associated with DNA but are not the genetic material themselves.

Question 13

Chargaff's rules for the pairing of nitrogen bases is

Accepted Answer

Chargaff's rules state that adenine (A) always pairs with thymine (T) and guanine (G) always pairs with cytosine (C). In other words, A=T and G=C. This pairing rule is known as complementary base pairing.

Question 14

Avery and his coworkers showed that the agent responsible for changing nonvirulent bacteria into virulent bacteria was

Accepted Answer

Avery and his coworkers showed that the agent responsible for changing nonvirulent bacteria into virulent bacteria was DNA, by demonstrating that purified DNA from virulent strains of bacteria could transform nonvirulent strains into virulent ones.

Question 15

Watson and Crick developed a model of DNA in which the two strands twist into the shape of a ________.

Accepted Answer

Watson and Crick developed the double helix model of DNA, in which the two strands twist around each other like a twisted ladder or spiral staircase. The model consists of two strands of nucleotides that are held together by hydrogen bonds between complementary base pairs (A-T and C-G), forming a double-stranded helix structure.

Question 16

Nucleotides have a phosphate group attached at the ________ carbon atom of the sugar.

Accepted Answer

The phosphate group is attached to the 5' carbon atom of the sugar in nucleotides. This linkage between the sugar and phosphate group forms the backbone of DNA and RNA molecules.

Question 17

Which enzyme adds new nucleotides to the end of a growing strand?

Accepted Answer

Polymerase is the enzyme that adds new nucleotides to the end of a growing strand during DNA replication.

Question 18

DNA consists of two antiparallel strands of nucleotides held together by

Accepted Answer

DNA consists of two antiparallel strands of nucleotides held together by hydrogen bonds between the nitrogenous bases. The sugar-phosphate backbone of each strand is held together by covalent bonds. Peptide bonds are the bonds that hold amino acids together in proteins, and ionic bonds are the attractions between oppositely charged ions.

Question 19

Viruses that attack bacteria are called

Accepted Answer

Viruses that attack bacteria are called bacteriophages or phages. Provirus refers to the viral DNA that is integrated into the host cell's genome. Virulent describes a virus that causes severe disease. Lytic refers to the process by which a virus infects a cell, replicates, and causes the cell to burst, releasing new virus particles.

Question 20

Which statement about the Hershey-Chase experiment is false?

Accepted Answer

In the Hershey-Chase experiment, only the DNA was labeled with radioactive phosphorus and the protein was labeled with radioactive sulfur. Therefore, statement D is false as the virus-infected bacteria did not contain radioactive sulfur.

Quiz 14: Dna: the Genetic Material