Chapter 4. DNA, RNA, and the Flow of Genetic Information

Question 1

in elongation of polymers, the initial segment of the polymer that is to be extended and on which elongation is dependent.

Answer 1

Primer

Question 2

template for protein synthesis. The base sequence of mRNA is complimentary to a gene in DNA.

Answer 2

Messenger RNA (mRNA)

Question 3

A nitrogenous base that includes a pyrimidine ring fused with a five-membered imidazole ring; the purine derivatives adenine and guanine are found in nucleotides and nucleic acids.

Answer 3

Purine

Question 4

a purine or pyrimidine base linked to a sugar.

Answer 4

Nucleoside

Question 5

a nitrogenous base that is a six-membered heterocyclic ring containing two nitrogen and four carbon atoms; the pyrimidine derivatives cytosine, uracil and thymine are found in nucleotides and nucleic acids.

Answer 5

Pyrimidine

Question 6

a five-carbon monosaccharide (C5H9O5) that constitutes the carbohydrate moiety of deoxynucleotides; the deoxyribose commonly found in these molecules is 2-deoxyribose.

Answer 6

Deoxyribose

Question 7

a nitrogenous purine or pyrimidine base linked to a sugar that is in turn linked to one or more phosphate groups.

Answer 7

Nucleotide

Question 8

a large ribonucleoprotein assembly that catalyzes the formation of peptide bonds; a molecular machine that coordinates protein synthesis.

Answer 8

Ribose

Question 9

enzymes that catalyze the template-directed, primer-dependent addition of deoxynucleotide units, using deoxynucleotide triphosphates as substrates, to the 3’ end of the DNA chain; chain growth is in the 5’-to 3’-direction; such enzymes replicate and repair DNA.

Answer 9

DNA polymerase

Question 10

an enzyme that synthesizes DNA using an RNA template.

Answer 10

Reverse transcriptase

Question 11

A right-handed double helix with the following characteristics: the two strands are antiparallel; the bases are inside the helix and the phosphates and deoxyribose sugars are on the outside; adenine forms hydrogen bonds with thymine, and guanine forms them with cytosine; the bases in each pair are coplanar; there are 10.4 residues per turn, with a pitch of 35 Å.

Answer 11

B-DNA

Question 12

A structure composed of two intertwined DNA strands such that the sugar-phosphate backbone lies on the outside and the bases on the inside. The two strands run in opposite directions.

Answer 12

double helix

Question 13

A right-handed double helix made up of antiparallel strands held together by A-T and G-C base pairing; it is wider and shorter than B-DNA and is seen in dehydrated DNA as well as in doublestranded regions of RNA and in RNA-DNA helices.

Answer 13

A-DNA

Question 14

the relationship between nucleic acid sequence information and protein sequence information.

Answer 14

Genetic code

Question 15

A linear polymer of nucleotide monomers joined by 3’ to 5’ phosphodiester linkages; each monomer consists of a sugar, a phosphate, and one of four bases. Two of the bases are derivatives of purine - adenine (A) and guanine (G) - and two of pyrimidine - cytosine (C) and thymine (T). The sugar units in DNA are deoxyriboses.

Answer 15

deoxyribonucleic acid (DNA)

Question 16

generation of unique but related mRNA molecules by the differential splicing of the pre-mRNA transcript. By allowing the synthesis of more than one mRNA from a pre-mRNA transcript, alternative splicing increases the coding potential of the genome.

Answer 16

Alternative splicing

Question 17

regions of the pre-mRNA that are retained in the mature mRNA.

Answer 17

Exon

Question 18

a hypothesis that suggests that new proteins arose in evolution by rearranging exons that encoded discrete structural elements.

Answer 18

Exon shuffling

Question 19

regions of the primary transcript that are removed in the mature mRNA; also called intervening sequences.

Answer 19

Intron

Question 20

nucleotide triplet in mRNA that codes for a particular amino acid.

Answer 20

Codon

Question 21

Three-nucleotide sequence of tRNA that base-pairs with a codon in mRNA.

Answer 21

Anticodon

Question 22

RNA molecule 22-nucleotides in length that possesses the regulatory activity when bound to members of a class of proteins called the Argonaute family.

Answer 22

Micro RNA (miRNA)

Question 23

A class of small RNA molecules that bind to mRNA and facilitate its degradation.

Answer 23

Small interfering RNA (siRNA)

Question 24

the duplication of DNA in which one of the strands of each daughter molecule is newly synthesized while the other is unchanged from the parental DNA double helix.

Answer 24

Semiconservative replication

Question 25

A left-handed double helix in which the backbone phosphates zigzag; can be formed by oligonucleotides with alternating sequences of purines and pyrimidines.

Answer 25

Z-DNA

Question 26

cellular protein synthesis, so-named because the four-letter alphabet of nucleic acids is translated into the different amino acid alphabet of proteins.

Answer 26

Translation

Question 27

RNA component of ribosomes, the site of protein synthesis.

Answer 27

Ribosomal RNA (rRNA)

Question 28

the adapter molecule in protein synthesis. It contains an amino acid recognition site as well as a template-recognition site, or anticodon.

Answer 28

Transfer RNA (tRNA)

Question 29

DNA-directed synthesis of RNA catalyzed by RNA polymerase.

Answer 29

Transcription

Question 30

a sequence of DNA or RNA which directs the production of a complementary sequence.

Answer 30

Template

Question 31

a class of small RNAs that are confined to the nucleus. Some of these play a role in splicing.

Answer 31

Small nuclear RNA (snRNA)

Question 32

a large ribonucleoprotein assembly that catalyzes the formation of peptide bonds; a molecular machine that coordinates protein synthesis.

Answer 32

Ribosome

Question 33

A long unbranched polymer consisting of nucleotides joined by 3’ - to - 5’ phosphodiester linkages. In contrast to DNA, the sugar units in RNA are riboses, and one of its four major bases is uracil (U) instead of thymine (T).

Answer 33

ribonucleic acid (RNA)

Question 34

an assembly of proteins and small nuclear RNAs that splices primary transcripts to mature mRNA.

Answer 34

Spliceosomes

Question 35

In messenger RNA, a purine-rich region about 10 nucleotides on the 5’ side of an initiator codon that pairs with the 3’ end of 16S RNA in the 30S ribosomal subunit; helps to determine where translation is initiated on an mRNA molecule.

Answer 35

Shine-Dalgarno sequence

Question 36

A specific sequence of DNA, usually just upstream of a gene, that specifies the site and extent of transcription of the associated gene.

Answer 36

Promoter site

Question 37

a class of enzymes that synthesize RNA molecules complementary to a DNA template.

Answer 37

RNA polymerase

Question 38

the removal of introns and the ligation of exons from precursors of RNA to form mature RNA.

Answer 38

Splicing