AP Bio Chapter 13 and 14

If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine?

0%

Enzyme used during replication to attach Okazaki fragments to each other

DNA ligase

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium?

Extract plasmid DNA from bacterial cells. Cut the plasmid DNA using restriction enzymes. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. Use ligase to seal plasmid DNA to nonplasmid DNA. Transform bacteria with a recombinant DNA molecule.

Which of the following statements best describes the eukaryotic chromosome?

It consists of a single linear molecule of double-stranded DNA plus proteins.

Which of the following statements accurately describes why Taq polymerase is used in PCR?

It is heat stable and can withstand the heating step of PCR.

Figure 1 shows some relevant details of a model of how a deoxynucleotide, in this case dTMP, is added to a growing strand of DNA. Figure 1. Model showing details of adding a deoxythymidine monophosphate ( dTMP) nucleotide to a growing strand of DNA. The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5' to 3' direction?

The phosphate group, attached to the 5' carbon of the dTMP, forms a covalent bond with the oxygen atom attached to the 3' carbon of the growing strand.

How does a bacterial cell protect its own DNA from restriction enzymes?

by adding methyl groups to adenines and cytosines

Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. Your strategy should be to

cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.

During DNA replication, which of the following enzymes separates the DNA strands during replication?

helicase

Which of the following modifications is most likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?

increasing the length of the DNA fragment

Which of the following enzymes synthesizes short segments of RNA?

primase

An Okazaki fragment has which of the following arrangements?

5' RNA nucleotides, DNA nucleotides 3'

At a specific area of a chromosome, the following sequence of nucleotides is present where the chain opens to form a replication fork: 3'-C C T A G G C T G C A A T C C-5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5'-A C G U U A G G-3'

Why is it so important to be able to amplify DNA fragments when studying genes?

A gene may represent only a millionth of the cell's DNA.

Figure 1 illustrates a model of the molecules involved in DNA replication and their placement relative to each other. Figure 1. Model including molecules involved in DNA replication. Which of the following correctly explains where DNA replication will begin on the 5'-3' strand oriented , reading from left to right?

DNA replication will be initiated immediately to the left of the RNA, since DNA polymerase requires an RNA primer.

A student analyzed a viral genome and found that the genome had the following nucleotide composition. • 28% adenine • 20% thymine • 35% cytosine • 17% guanine Which of the following best describes the structure of the viral genome?

Double-stranded DNA

Which of the following statements correctly describes chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Which of the following statements correctly describes one characteristic of histones?

Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.

Why do histones bind tightly to DNA?

Histones are positively charged, and DNA is negatively charged.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

A model of a process involving nucleic acids is shown in Figure 1. Figure 1. Model of a process involving nucleic acids Which of the following best explains what process is represented in Figure 1 ?

New DNA strands are being synthesized in the 5' to 3' direction from their DNA templates.

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

No replication fork will be formed

Which of the following best describes a characteristic of DNA that makes it useful as hereditary material?

Nucleotide bases in one strand can only be paired with specific bases in the other strand.

Which of the following statements best explains the structure and importance of plasmids to prokaryotes?

Plasmids are circular, double-stranded DNA molecules that provide genes that may aid in survival of the prokaryotic cell.

Which of the following statements describes one difference between DNA replication in prokaryotes and DNA replication in eukaryotes?

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

Erwin Chargaff investigated the nucleotide composition of . He analyzed from various organisms and measured the relative amounts of adenine (A), guanine (G), cytosine (C), and thymine (T) present in the of each organism. Table 1 contains a selected data set of his results. Which of the following statements best explains the data set?

Since the %A and the %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.

What is meant by the description "antiparallel" regarding the two strands of nucleic acids that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

DNA and RNA are nucleic acids that can store biological information based on the sequence of their nucleotide monomers. Figure 1 shows a short segment of each of the two types of nucleic acids. Which of the following best describes a structural difference between DNA and RNA?

The backbone of DNA contains deoxyribose, whereas the backbone of RNA contains ribose.

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

The cell's DNA couldn't be packed into its nucleus.

A scientist adds a chemical to a culture of dividing cells in order to disrupt DNA replication. The replicated DNA produced by the cells is double-stranded, but sections of it lack covalent bonds between adjacent nucleotides (Figure 1). Figure 1. Replicated DNA produced after a chemical is introduced. Which of the following claims is best supported by the data?

The chemical inhibits DNA ligase.

Which of the following statements best explains how the genes for antibiotic resistance can be transmitted between bacteria without the exchange of bacterial chromosomal DNA?

The genes for antibiotic resistance are located on a plasmid that can be passed to neighboring bacteria.

Which of the following best explains why ligase is required for DNA replication?

The lagging strand cannot be replicated continuously, and ligase is needed to join the fragments.

Which of the following sets of materials is required by both eukaryotes and prokaryotes for DNA replication?

double-stranded DNA, four kinds of DNA nucleotides, primers, origins of replication

During DNA replication, which of the following enzymes covalently connects segments of DNA?

ligase

In which order do the necessary enzymes act to repair a thymine dimer by nucleotide excision repair?

nuclease, DNA polymerase, DNA ligase

Which of the following lists of structures correctly represents the order of increasingly higher levels of organization of chromatin?

nucleosome, 30-nm chromatin fiber, looped domain

What is the function of topoisomerase?

relieving strain in the DNA ahead of the replication fork

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand binding proteins

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

the 30-nm chromatin fiber

The leading and the lagging strands of DNA formed during DNA replication differ in that

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 difference between ATP and the nucleoside triphosphates used during DNA synthesis is that

the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

What is the function of DNA polymerase III?

to add nucleotides to the 3' end of a growing DNA strand

When DNA replicates, each strand of the original DNA molecule is used as a template for the synthesis of a second, complementary strand. Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?

D

Suppose you are provided with an actively dividing culture of Escherichia coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

DNA in both daughter cells would be radioactive.

Enzyme used to position nucleotides during DNA replication

DNA polymerase

During DNA replication, which of the following enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

DNA polymerase I

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

DNA polymerase III

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end.

Cells that contain only circular chromosomes are most probably which of the following?

Bacterial cells