The Molecular Basis of Heredity

The Molecular Basis of Heredity

By Lauren Ayers

Multiple Choice

Which of the following results from Griffith’s experiment is an example of transformation?

• Mouse dies after being injected with living S cells.

• Mouse is healthy after being injected with living R cells.

• Mouse is healthy after being injected with heat-killed S cells.

• Mouse dies after being injected with a mixture of heat- killed S and living R cells.

Multiple Choice

Avery and his colleagues' 1944 experiment showed that DNA __________.

• consists of sugars, phosphate groups, and bases

• was the substance that transformed the bacteria in Griffith's experiment

• has two strands held together with hydrogen bonds

• ontains adenine, guanine, thymine, and cytosine

Multiple Choice

A scientist assembles a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have __________.

• the protein and DNA of T4

• the protein of T2 and the DNA of T4

• the protein of T4 and the DNA of T2

• a mixture of the DNA and proteins of both phages

Multiple Choice

Chargaff found that for DNA __________.

• A + T = G + C

• A + T = 50% of the total bases

• the ratio of A to G is close to 1:1 and the ratio of T to C is close to 1:1

• the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1

Multiple Choice

Which of the following techniques was most helpful to Watson and Crick in developing their model for the structure of DNA?

• Radioactive labeling

• X-ray crystallography

• Cloned DNA

• Electrophoresis

Multiple Choice

The two antiparallel strands of nucleotides that form the DNA double helix are held together by

• hydrogen bonds between nucleotide bases

• ionic bonds between guanine and cytosine

• 5' deoxyribose and phosphate bonds

• ovalent bonds between nitrogen atoms in adenine and in thymine

Multiple Choice

The experiments of Meselson and Stahl showed that DNA __________.

• contains complementary base pairing

• codes for the amino acid sequences of proteins

• is composed of nucleotides

• replicates in a semiconservative fashion

Multiple Choice

Which of the following statements accurately describes differences between DNA replication in prokaryotes and DNA replication in eukaryotes?

• Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not.

• Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

• The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes.

• Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.

Multiple Choice

DNA strands are antiparallel. Which of the following statements defines "antiparallel"?

• The double helix structure of DNA creates nonparallel strands.

• A 5' to 3' DNA strand is paired with the 3' to 5' DNA strand.

• Hydrogen bonds between base pairs cause DNA strands to cross.

• One DNA strand contains bases that complement the bases in the opposite strand.

Multiple Choice

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA in DNA replication?

• The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

• The lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together.

• The leading strand is synthesized at twice the rate of the lagging strand.

Multiple Choice

 The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

• DNA ligase, replication fork proteins, adenylyl cyclase

• telomerase, helicase, single-strand binding protein

• nuclease, DNA polymerase, DNA ligase

• telomerase, primase, DNA polymerase

Multiple Choice

Which answer best describes the role of telomerase in replicating the ends of linear chromosomes?

• It adds a 5' cap structure to the chromosome ends that resists degradation by nucleases.

• It causes specific double-strand DNA breaks that result in blunt ends on both strands.

• It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.

• It adds numerous GC pairs, which resist hydrolysis and maintain chromosome integrity.