Chapter 16

Question 1

(1) The conversion of a normal animal cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell.

Answer 1

Transformation

Question 2

A virus that infects bacteria; also called a phage.

Answer 2

Bacteriophages (Phages)

Question 3

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

Answer 3

Double Helix

Question 4

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

Answer 4

Semiconservative Model

Question 5

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

Answer 5

Origins of Replication

Question 6

A Y-Shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are growing.

Answer 6

Replication Fork

Question 7

An enzyme that untwists the double helix of DNA at the replication forks, separating the two strands and making them available as template strands.

Answer 7

Helicases

Question 8

A protein that breaks, swivels, and rejoins strands. During DNA replication, ____ helps to relieve strain in the double helix ahead of the replication fork.

Answer 8

Topoisomerase

Question 9

A short stretch of RNA with a free 3’ end, bound by complementary base pairing to the template strand, that is elongated with DNA nucleotides during DNA replication.

Answer 9

Primer

Question 10

An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3’ end of an existing chain.

Answer 10

DNA Polymerases

Question 11

The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’-> 3’ direction.

Answer 11

Leading Strand

Question 12

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5’->3’ direction away from the replication fork

Answer 12

Lagging Strand

Question 13

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

Answer 13

Okazaki Fragments

Question 14

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3; end of one DNA fragment (such as an Okazaki fragment) to the 5’ end of another DNA fragment (such as a growing DNA chain).

Answer 14

DNA Ligase

Question 15

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.

Answer 15

Nuclease

Question 16

The tenderly repetitive DNA at the end of a eukaryotic chromosome’s DNA molecule that protects the organism’s genes from being eroded during successive rounds of replication.

Answer 16

Telomeres

Question 17

A dense region of DNA in a prokaryotic cell.

Answer 17

Nucleoid

Question 18

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

Answer 18

Chromatin