Chapter 14: DNA The Genetic Material

Question 1

DNA

Answer 1

Deoxyribonucleic acid. A molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. Contains 5-carbon sugar, phosphate group, and nitrogen-containing base (purine or pyrimadine)

Question 2

pyrimidine

Answer 2

Produces RNA and DNA, proteins and starches, the regulation of enzymes and cell signaling.

Question 3

purine

Answer 3

Produces of RNA and DNA, proteins and starches, the regulation of enzymes and cell signaling.

Question 4

thymine dimer

Answer 4

UV light causes a covalent bond to form between adjacent thymine bases on the same strand, in the next round of replication will often cause incorrect base to be substituted in the new strand

Question 5

thymine

Answer 5

a pyrimidine base, C 5 H 6 N 2 O 2, that is one of the principal components of DNA, in which it is paired with adenine.

Question 6

base-pair

Answer 6

Two chemical bases bonded to one another forming a “rung of the DNA ladder.” The DNA molecule consists of two strands that wind around each other like a twisted ladder. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups.

Question 7

origins of replication

Answer 7

A particular sequence in a genome at which replication is initiated. This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses.

Question 8

topoisomerase

Answer 8

Enzyme that cuts and rejoins helix to prevent tangling.

Question 9

DNA ligase

Answer 9

An enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments.

Question 10

replisome

Answer 10

Macromolecular assembly formed by enzymes involved in DNA replication; two main subcomponents: primosome (primase and helicase) and a complex of DNA Pol III enzymes.

Question 11

phosphate group

Answer 11

A functional group or radical comprised of phosphorus attached to four oxygen, and with a net negative charge, thus represented as PO4.

Question 12

adenine

Answer 12

One of the two purine nucleobases (the other being guanine) used in forming nucleotides of the nucleic acids. In DNA, adenine binds to thymine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, which is used for protein synthesis, adenine binds to uracil.

Question 13

uracil genetics

Answer 13

One of four chemical bases that are part of RNA. The other three bases are adenine (A), cytosine (C), and guanine (G). In DNA, the base thymine (T) is used in place of uracil.

Question 14

antiparallel

Answer 14

A single strand of DNA has an inherent polarity. 5’ and 3’ ends.

Question 15

DNA pol I

Answer 15

Acts on the lagging strand to remove primers and replace them with DNA

Question 16

DNA pol III

Answer 16

Main replication enzyme; it is responsible for the bulk of DNA synthesis

Question 17

primase

Answer 17

An enzyme involved in the replication of DNA. DNA primase is a type of RNA polymerase which creates a RNA primer (later this RNA piece is removed by a 5’ to 3’ exonuclease); next, DNA polymerase uses the RNA primer to replicate ssDNA.

Question 18

leading strand

Answer 18

Strand of DNA that is synthesized continuously.

Question 19

telomeres

Answer 19

Structures at the ends of eukaryotic chromosomes protecting the ends of chromosomes from nucleases and maintain the integrity of linear chromosomes; composed of specific DNA sequences.

Question 20

nitrogenous base

Answer 20

Main function of a nitrogenous base is to bond nucleic acids together. A nitrogenous, or nitrogen-containing, base is an organic molecule with a nitrogen atom that has the chemical properties of a base. A nitrogenous base owes its basic properties to the lone pair of electrons of a nitrogen atom.

Question 21

guanine

Answer 21

One of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine.

Question 22

phosphodiester bond

Answer 22

The type of bond that links the nucleotides in DNA or RNA. joins the phosphate group of one nucleotide to the hydroxyl group on the sugar of another nucleotide.

Question 23

semiconservative model

Answer 23

Model of DNA replication. When a doule helix replicates, each of two daughter molecules will have one old and one new strand.

Question 24

DNA gyrase

Answer 24

Topoisomerase involved in DNA replication.

Question 25

lagging strand

Answer 25

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

Question 26

telomerase

Answer 26

Uses internal RNA as a template and not the DNA itself; allows short stretches of DNA to be synthesized.

Question 27

cytosine

Answer 27

Cytosine is one of the four main bases found in DNA and RNA, along with adenine, guanine, and thymine.

Question 28

Chargaff’s rule

Answer 28

The nucleotides C to G and A to T ratios were the same in all organisms.

Question 29

DNA polymerase

Answer 29

Add new bases to the 3’ end of existing strands, extending in the 5’ to 3’ direction; DNA polymerase require a primer to begin synthesis; they cannot begin without a strand of RNA or DNA base-paired to the template (RNA polymerases do not have this requirement, so they usually synthesize the primers.

Question 30

helicase

Answer 30

Enzyme that uses energy from ATP to unwind the DNA template (strands are unstable because their hydrophobic bases are exposed to water).

Question 31

single strand binding protein (SSB)

Answer 31

A protein that coats exposed single strands in order to remain stable

Question 32

Okazaki fragments

Answer 32

Short fragments of DNA that are a result of the synthesis of the lagging strand during DNA replication.