AP Bio Midterm Key Terms Ch. 16

Question 1

bacteriophage

Answer 1

A virus that infects bacteria; also called a phage.

Question 2

DNA ligase

Answer 2

A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of a new DNA fragment to the 5’ end of a growing chain.

Question 3

DNA polymerase

Answer 3

An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.

Question 4

double helix

Answer 4

for of native DNA, referring to its adjacent polynucleotide strands wound into a spiral shape

Question 5

helicase

Answer 5

enzyme that untwists the double helix of DNA at the replication forks

Question 6

lagging strand

Answer 6

a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork

Question 7

leading strand

Answer 7

new continuous complementary DNA strand synthesized along the template strand in the mandatory 5’ to 3’ direction

Question 8

mismatch repair

Answer 8

cellular process that uses special enzymes to fix incorrectly paired nucleotides

Question 9

nuclease

Answer 9

enzyme that hydrolyzes DNA and RNA into their component nucleotides

Question 10

nucleotide excision repair

Answer 10

process of removing and then correctly replacing a damaged segment of DNA using the undamaged strand as a guide

Question 11

Okazaki fragment

Answer 11

short segment of DNA synthesized on a template strand during DNA replication; many Okazaki fragments make up the lagging strand of newly synthesized DNA

Question 12

origin of replication

Answer 12

site where the replication of a DNA molecule begins

Question 13

phage

Answer 13

a virus that infects bacteria; also called a bacteriophage

Question 14

primase

Answer 14

an enzyme that joins RNA nucleotides to make the primer

Question 15

primer

Answer 15

A polynucleotide with a free 3´ end, bound by complementary base pairing to the template strand, that is elongated during DNA replication.

Question 16

replication fork

Answer 16

A Y-shaped region on a replicating DNA molecule where new strands are growing.

Question 17

semiconservative model

Answer 17

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.

Question 18

single-strand binding protein

Answer 18

During DNA replication, molecules that line up along the unpaired DNA strands, holding them apart while the DNA strands serve as templates for the synthesis of complementary strands of DNA.

Question 19

telomerase

Answer 19

An enzyme that catalyzes the lengthening of telomeres. The enzyme includes a molecule of RNA that serves as a template for new telomere segments.

Question 20

telomere

Answer 20

The protective structure at each end of a eukaryotic chromosome. Specifically, the tandemly repetitive DNA at the end of the chromosome’s DNA molecule

Question 21

topoisomerase

Answer 21

A protein that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.

Question 22

transformation

Answer 22

(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.