Chapter 16

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information. Which of the following characteristics of DNA is responsible for this?

Sequence of Bases

Origin of Replication

Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides

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

The cell's DNA could not be packed into its nucleus.

Mismatch repair

The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope

Transformation

The conversion of a normal animal cell to a cancerous cell. A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of different species, , transformation results in horizontal gene transfer

Double helix

The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape

Which of the following statements correctly describes the difference between the leading and the lagging strands of DNA during 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.

Euchromatin

The less condensed form of eukaryotic chromatin that is available for transcription

Which of the following statements correctly describes the difference between ATP and the nucleotides used during DNA synthesis?

The nucleotides have the sugar deoxyribose; ATP has the sugar ribose.

DNA Replication

The process by which a DNA molecule is copied; also called DNA synthesis

Telomere

The tandemly repetitive DNA at the end of a eukaryotic chromosome's DNA molecule

Semiconservative model

Type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and one newly made strand

Which of the following characteristics would you expect of a eukaryotic organism that lacks the enzyme telomerase?

a reduction in chromosome length in gametes

Primer

a short stretch of RNA with a free 3' end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication

At a specific area of a chromosome, the sequence of nucleotides below 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'

In an analysis of the nucleotide composition of a molecule of DNA, which of the following combinations of base pairs will be found?

A + C = G + T

Replication Fork

A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized

DNA ligase

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of one DNA fragment to the 5' end of another DNA fragment

Nucleoid

A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated

Okazaki fragments

A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication. Many such segments are joined together to make up the lagging strand of newly synthesized DNA

Bacteriophage

A virus that infects bacteria

DNA polymerase

An enzyme that catalyzes the elongation of new DNA by the addition of nucleotides to the 3' end of an existing chain

Nuclease

An enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides

Virus

An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (caspid) and, sometimes a membranous envelope

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction?

DNA polymerase III

DNA replication is said to be semiconservative. What does this mean?

Each new double helix consists of one old and one new strand

Heterochromatin

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed

Which of the following statements describes the process of transformation in bacteria?

External DNA is taken into a cell, becoming part of the cell's genome.

Which of the following statements correctly describes the structure of chromatin?

Heterochromatin is highly condensed, whereas euchromatin is less compact.

Which of the following is true of DNA during interphase?

It exists as chromatin and is less condensed than mitotic chromosomes.

Which of the following statements accurately describes the structure of a eukaryotic chromosome?

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

In his transformation experiments, what phenomenon did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.

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

No replication fork will be formed

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

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

Antiparallel

Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix ( they run in opposite 5'---> 3' directions)

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). Which two classes of DNA do these different samples represent?

leading strands and Okazaki fragments

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

nucleosome, 30-nm chromatin fiber, looped domain

In E. coli, what is the function of DNA polymerase III?

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