Unit 6: Chapter 15 BSG

The genome of a newly discovered virus has the following nucleotide composition: 22% guanine, 16% cytosine, 34% adenine, and 28% uracil. Based on the nucleotide composition, the genome of this virus is most likely made of which of the following?

• single-stranded DNA

• double-stranded DNA

• single-stranded RNA

• double-stranded RNA

Prokaryotic genomes are packaged into chromosomes in the.

• circular; nucleoid region

• circular; nucleus

• linear; nucleoid region

• linear; nucleus

Energy is required to separate the two strands of the DNA double helix because of the hydro-gen bonds between the base pairs. Based on the base pair content, which of the following would require the least amount of energy to separate the strands of DNA?

• 20% G, 20% C, 30% A, 30% T

• 30% G, 30% C, 20% A, 20% T

• 15% A, 15% T, 35% G, 35% C

• 25% G, 25% C, 25% A, 25% T

Which of the following correctly describes a struc-tural difference between DNA and RNA?

• DNA has a five-carbon sugar; RNA has a four-carbon sugar.

• DNA has thymine; RNA has uracil.

• DNA has adenine; RNA has cytosine.

• DNA is typically single-stranded; RNA is typi-cally double-stranded.

After one round of DNA replication, which of the following results would support the statement "DNA replication is semiconservative"?

• All DNA molecules have one strand contain-ing N-14 and one strand containing N-15.

• 50% of the DNA molecules only contain N-14. and 50% of the DNA molecules only contain N-15.

• All DNA molecules only contain N-15.

• All DNA molecules only contain N-14.

After two rounds of DNA replication, which of the following results would support the statement "DNA replication is semiconservative"?

• All DNA molecules have one strand contain-ing N-14 and one strand containing N-15.

• 50% of the DNA molecules only contain N-14, and 50% of the DNA molecules only contain N-15.

• All DNA molecules only contain N-15.

• 50% of the DNA molecules contain only N-14, and 50% of the DNA molecules have one strand containing only N-15 and one strand containing only N-14.

Why does DNA replication proceed continuously on one strand of the double helix but discontinu-ously on the other strand of the double helix?

• One strand of the double helix contains thy-mine, and the other strand contains uracil.

• Only G and C nucleotides appear on one strand of the double helix, and only A and T nucleotides appear on the other strand of the double helix.

• RNA polymerase can only synthesize RNA primers on one strand of the double helix.

• DNA polymerase can only add new nucleo-tides in the 5' to 3' direction.

The enzyme unwinds the double helix of DNA, and the enzyme. relieves the supercoiling created by this unwinding.

• helicase; topoisomerase

• DNA polymerase; topoisomerase

• DNA polymerase; ligase

• helicase; ligase

The enzyme. adds new nucleotides to both the lagging and leading strand, and the enzyme joins the discontinuous segments synthesized on the lagging strand.

• helicase; topoisomerase

• DNA polymerase; topoisomerase

• DNA polymerase; ligase

• helicase; ligase

Which of the following are small, circular pieces of extranuclear DNA that can be found in either prokaryotes or eukaryotes?

• Okazaki fragments

• RNA primers

• plasmids

• linear chromosomes