Lecture 4: Bacterial Genetics

Question 0

What perfect of bacterial and human genomes have known function?

Answer 0

75% B

10% human

Question 1

What shape is bacterial DNA, and how many genes?

Answer 1

Circular

2,000-5,000 genes

Question 2

Why is the 16sRNA gene the genetic basis for identification and classification of bacteria?

Answer 2

Both conserved and variable regions

Question 3

In bacteria, what is an operon?

Answer 3

Genes with related function that all share the same regulatory elements

Question 4

What substances regulate transcription in humans and bacteria?

Answer 4

Humans: proteins interact with promoter
B: metabolic products or deficiencies (nutritional status)

Question 5

In addition to nutritional status, what regulates bacterial transcription?

Answer 5

Cell surface sensing

Quorum sensing

Question 6

What test uses bacteria to predict if an agent could be a carcinogen to eukaryotic cells?

Answer 6

Ames test

Question 7

Which more commonly leads to antibiotic resistance:
Mutations in B Chromosome, or
Acquisition of genes from other B?

Answer 7

Acquisition of genes

Question 8

Which method of gene exchanged involves DNA from dead bacteria taken up non-specifically by live bacteria?

Answer 8

Transformation

Question 9

Which method of gene exchanged allows the S. pneumonii capsule gene to be transferred?

Answer 9

Transformation

Question 10

What are practical uses of transformation?

Answer 10

recombinant hepatitis B vaccine, recombinant insulin,

and virus vectors for gene therapy

Question 11

Why is gene exchange by transformation and recombination rare?

Answer 11

Restriction/modification mechanism
DNA with defined patterns is methylated
Non-host DNA is modified differently than host
Restriction enzymes digest non-host DNA

Question 12

Which gene exchange method is characterized by the F factor plasmid, sex pili, and live bacteria?

Answer 12

Conjugation

Question 13

Which gene exchange method transfers antibiotic resistance genes among intestinal bacteria?

Answer 13

Conjugation

Question 14

Define Hfr as it relates to conjugation

Answer 14

Make with integrated plasmid due to high frequency of recombination

Question 15

Which gene exchange method involves a virus which mediates genetic exchange between bacteria?

Answer 15

Transduction

Question 16

What is generalized transduction?

Answer 16

Lyric

Lyric virus infects bacterium, DNA is released, taken up by bacteriophage virus and carried to another bacterium

Question 17

What is specialized transduction?

Answer 17

Lysogenic
Bacteriophage inserts into B chromosome (lysogeny), produces prophage in xs. Prophage excised itself and bring adjacent B DNA with it. Carried to another bacterium

Question 18

Through what gene exchange method are toxins for diphtheria, botulism, cholera, and scarlet fever transferred?

Answer 18

Transduction

Question 19

What are segments of non-xs DNA that carry genes for antibiotic resistance called?

Answer 19

R-factors

Question 20

What is an at factor which is also an F factor?

Answer 20

A large R factor plasmid

Question 21

What are the two mobile genetic elements?

Answer 21

Transposons and integerons

Question 22

What do compound transposons confer?

Answer 22

Multi-drug resistance

Question 23

What types of genes do transposons usually encode?

Answer 23

Enzymes for drug resistance

Question 24

What is a region of DNA which has several adjacent genes which contribute to pathogenesis of a disease?

Answer 24

Pathogenicity island

Question 25

Through what gene exchange methods can pathogenicity islands be transferred?

Answer 25

Transformation, conjugation, or transduction

Question 26

What is the difference between toxic and non-toxic E. coli?

Answer 26

Presence of Pathogenicity island