Chapter 7

Question 1

The DNA code

Answer 1

discovered in 1953 by James Watson and Francis Crick

Question 2

Nucleotide

Answer 2

basic unit of DNA;
phosphate, deoxyribose, nitrogenous base

Question 3

Transcription

Answer 3

1) RNA polymerase binds to the promoter, and DNA unwinds at the beginning of the gene
2) mRNA is synthesized by complementary base pairing
3) the site of synthesis moves along DNA; DNA that has been transcribed rewinds
4) transcription reaches terminator
5) RNA and RNA polymerase are released, and the DNA helix reforms

Question 4

mRNA
tRNA
rRNA

Answer 4

encodes proteins
moves amino acids
forms the ribosomes

Question 5

Enzymes in DNA replication

Answer 5

Helicase
Primase
DNA Polymerase III
DNA Polymerase I
Ligase
Gyrase/Topoisomerase

Question 6

Helicase

Answer 6

unzipping

Question 7

Primase

Answer 7

synthesis of RNA primer

Question 8

DNA Polymerase III

Answer 8

Adding bases to DNA strand, proofreading

Question 9

DNA Polymerase I

Answer 9

Removing primer, closing gaps, removing mismatches

Question 10

Ligase

Answer 10

binds and repairs DNA

Question 11

Gyrase/Topoisomerase

Answer 11

supercoiling

Question 12

DNA Polymerase

Answer 12

in 5’ to 3’ direction

Question 13

Okazaki fragments

Answer 13

formed during the discontinued lagging strand synthesis

Question 14

Prokaryotic Transcription

Answer 14

occurs in nucleoid

Question 15

Bacteria (chracteristics of microbial genomes)

Answer 15

of chromosomes: single (haploid) copies of one or rarely two

type of nucleic acid: circular or linear

no histones, through chromosomes are associated with a small amount of nonhistone protein

Question 16

Archaea (Characteristics of Microbial Genomes)

Answer 16

of chromosomes: 1 haploid

plasmids: in some cells

circular DNA

histones present

Question 17

Eukarya (Characteristics of Microbial Genomes)

Answer 17

chromosomes: two or more (typically diploid)

plasminds: in some fungi, algae, and protozoa

linear DNA in nucleus; circular DNA in mitochondria and chloroplasts, and plasmids

Question 18

First X-Ray picture of DNA

Answer 18

taken in 1952;
created by Rosalind Franklin

Question 19

Nitrogenous Bases of DNA

Answer 19

guanine, cytosine, adenine, thymine

Question 20

DNA Ligase

Answer 20

links the Okazaki fragments to form the lagging strand;
catalyzes the formation of bonds between adjacent nucleotides in DNA;
seals nicks in the sugar-phosphate backbone of DNA

Question 21

Gyrase/Topoisomerase

Answer 21

facilitates supercoiling that allows chromosomes to fit in the space of a bacterial cell

Question 22

Codons

Answer 22

mRNA is translated in;
three nucleotides

Question 23

start codon

Answer 23

translation begins at;
AUG

Question 24

end codon

Answer 24

translation ends at nonsense codons: UAA, UAG, UGA

Question 25

Anticodon (tRNA); Codon (mRNA)

Answer 25

codes for a single amino acid

Question 26

P site (ribosome)

Answer 26

the place where the first tRNA sits

Question 27

A site (ribosome)

Answer 27

the second codon of the mRNA pairs with the second anticodon of the tRNA, carrying the second amino acid at the A site; the seond amino acid bonds to the first one by a peptide bond; this attaches the polypeptide to the tRNA in the P site

Question 28

E site

Answer 28

last site in the ribosome; releases the tRNA

Question 29

Trnascription and Translation

Answer 29

5' to 3' (DNA) 3' to 5' (antisense) 5' to 3' (sense) 5' to 3' (mRNA; gene copy)

Question 30

Ionizing Radiation

Answer 30

inducing DNA breaks on a sugar-phophate backbone (caused by X-rays or Y-rays); can cause a single-strand break or a double-strand break; has enough energy to break away an electron

Question 31

Nonionizing Radiation

Answer 31

causes cellular distress through heat generation that eventually leads to the formation of free radicals; causes atoms to vibrate and heats substances; does not have enough energy to break away electrons

Question 32

Nucleotide analogs

Answer 32

disrupt DNA and RNA replication

Question 33

Frameshift mutagens

Answer 33

result in nonsense mutations

Question 34

Types of mutations

Answer 34

point mutations frameshift mutations

Question 35

Point mutations

Answer 35

most common; one base pair is affected; insertions, deletions, and substitutions

Question 36

Frameshift mutations

Answer 36

nucleotide triplets after a mutation are replaced; inseritions or deletions

Question 37

The effect of a chemical mutagen (nitrous acid; NHO2)

Answer 37

chemically modifies adenine to hypoxanthine; cytosine pairs with hypoxanthine; resulting mutation: cytosine-guanine base pair

Question 38

Plasmids

Answer 38

can replicate independently of the bacterial chromosome; chromosomal fragments must integrate themselves into the bacterial chromosome in order to replicate

Question 39

Three means of genetic recombination in bacteria

Answer 39

conjugation transformation transduction

Question 40

Conjugation

Answer 40

a mean of genetic recombination in bacteria; direct contact through pilus; conjugative proteins replicate the plasmid

Question 41

Transformation

Answer 41

DNA uptake by a bacteria; must include the specific expression of proteins that can take up the DNA

Question 42

Trnasduction

Answer 42

transfer through a virus; bacteriophage transfers DNA from one bacteria to another; virus enters; replicates itself; by mistake replicates bacterial DNA as well; using its protein transfers DNA to another bacetria

Question 43

Genetics

Answer 43

the study of heredity; concerned with 1) how information in nucleic acids is expressed 2) how nucleic acids are duplicated and transmitted to progeny (genotype) 3) these processes account for the characteristics of progeny (phenotype)

Question 44

Additional DNA

Answer 44

plasmids; account for nonessential genes; types: fertility, bacteriocin, virulence, resistance

Question 45

Bacteriocin

Answer 45

antimicrobial peptide that inhibits or kills another bacteria

Question 46

The DNA Code

Answer 46

discovered in 1953 by James Watson Francis Crick; a large molecule; a nucleic acid; two strands form a double helix