Ch. 8 Microbial Genetics

Question 1

Genotype

Answer 1

the genetic makeup of an organism

Question 2

phenotype

Answer 2

expression of the genes

Question 3

Short tandem repeats (STRs)

Answer 3

repeating sequences of noncoding DNA

Question 4

Vertical gene transfer

Answer 4

flow of genetic information from one generation to the next

Question 5

DNA replication

Answer 5

• Topoisomerase and gyrase relax the strands
• Helicase separates the strands
• A replication fork is created

Question 6

DNA polymerase

Answer 6

adds nucleotides to the growing DNA strand

Question 7

Energy needs

Answer 7

– Energy for replication is supplied by nucleotides
– Hydrolysis of two phosphate groups on ATP
provides energy

Question 8

Risbosomal RNA (rRNA)

Answer 8

integral part of ribosomes

Question 9

Transfer RNA (tRNA)

Answer 9

transports amino acids during protein synthesis

Question 10

Messenger RNA (mRNA)

Answer 10

carries coded information from DNA to ribosomes

Question 11

transcription begins when RNA polymerase binds to the

Answer 11

promoter sequence on DNA

Question 12

transcription stops when it reaches the

Answer 12

terminator sequence on DNA

Question 13

Codons

Answer 13

groups of three mRNA nucleotides that code for a particular amino acid

Question 14

61 sense codons

Answer 14

encode the amino acids

Question 15

degeneracy

Answer 15

each amino acid is coded by sever codons

Question 16

Start Codon

Answer 16

AUG

Question 17

Stop codons

Answer 17

UAA, UAG, UGA

Question 18

tRNA molecules also have an

Answer 18

anticodon that base-pairs with the codon

Question 19

exons

Answer 19

regions on DNA that code for proteins

Question 20

introns

Answer 20

regions of DNA that do not code for proteins

Question 21

small nuclear ribonucleoprotiens (snRNPs)

Answer 21

remove introns and splice exons together

Question 22

repression

Answer 22

inhibits gene expression and decreases enzyme synthesis
-mediated by repressors, proteins that block transcription

Question 23

Induction

Answer 23

inhibits gene expression and decreases enzyme synthesis
- initiated by an inducer

Question 24

Promoter

Answer 24

segment of DNA where RNA polymerase initiates transcription of structural genes

Question 25

Operator

Answer 25

segment of DNA that controls transcription of structural genes

Question 26

Operon

Answer 26

set of operator and promoter sites and the structural genes they control

Question 27

inducible operon

Answer 27

structural genes are not transcribes unless an inducer is present

Question 28

repressible operons

Answer 28

structural genes are transcribes until they are turned off

Question 29

corepressor

Answer 29

represses the expression of genes

Question 30

catabolite repression

Answer 30

inhibits cells from using carbons sources other than glucose

Question 31

cyclic AMP (cAMP)

Answer 31

builds up in a cell when glucose is not available

Question 32

riboswitch

Answer 32

part of an mRNA molecule that binds to a substrate and changes the mRNA structure

Question 33

microRNAs (miRNAs)

Answer 33

base pair with mRNA to make it double-stranded

Question 34

mutation

Answer 34

a permanent change in the base sequence of DNA

Question 35

Mutagens

Answer 35

agents that cause mutations

Question 36

Spontaneous mutations

Answer 36

occur in the absence of a mutagen

Question 37

base substitution (point mutation)

Answer 37

change in one base in DNA

Question 38

missense mutation

Answer 38

base substitution results in change in an amino acid

Question 39

nonsense mutation

Answer 39

base substitution results in a nonsense (stop) codon

Question 40

frameshift mutations

Answer 40

-insertion or deletion of one or more nucleotide pairs -shifts the translational "reading frame"

Question 41

Nitrous acid

Answer 41

causes adenine to bind with cytosine instead of thymine

Question 42

nucleoside analog

Answer 42

incorporates into DNA in place of a normal base; causes mistakes in base pairing

Question 43

photolyases

Answer 43

separate thymine dimers

Question 44

nucleotide excision repair

Answer 44

enzymes cut out incorrect bases and fill in correct bases

Question 45

Spontaneous mutation rate

Answer 45

1 in 10^9 replicated base pairs or 1 in 10^6 replicated genes

Question 46

mutagens increase the mutation rate to

Answer 46

per 10^-5 or 10^-3 replicated gene

Question 47

positive (direct) selection

Answer 47

detects mutant cells because they grow or appear different than unmutated cells

Question 48

negative (indirect) selection

Answer 48

detects mutant cells that cannot grow or perform a certain function

Question 49

auxtotroph

Answer 49

mutant that has a nutritional requirement absent in the parent - use of replica plating

Question 50

Ames test

Answer 50

exposes mutant bacteria to mutagenic substances to measure the rate of reversal of the mutation

Question 51

Genetic recombination

Answer 51

exchange of genes between two DNA molecules; creates genetic diversity

Question 52

Crossing over

Answer 52

two chromosomes break and rejoin, resulting in the insertion of foreign DNA into the chromosomes

Question 53

Vertical gene transfer

Answer 53

transfer of genes from an organism to its offspring

Question 54

Horizontal gene transfer

Answer 54

transfer of genes between cells of the same generation

Question 55

moblie genetic elements

Answer 55

move from one chromosome to another or from one cell to another

Question 56

plasmids

Answer 56

self-replicating circular pieces of DNA

Question 57

Conjugative plasmid

Answer 57

carries genes for sez pili and transfer of the plasmids

Question 58

dissimilation plasmids

Answer 58

encode enzymes for the catabolism of unusual compounds

Question 59

resistance factors (R factors)

Answer 59

encode antibiotic resistance