Bacterial Genetics

Question 1

What does this:

allows coordinated response of multiple genes to environmental changes

Answer 1

control of gene expression

Question 2

What does the operan do?

Answer 2

it can activate or turn off expression of a gene or group of genes

Question 3

How is the operan kept under control?

Answer 3

by the promoter or repressor DNA sequence

Question 4

What does control of gene expression in pathogens alow for?

Answer 4

quorum sensing
pathogenicity islands
toxin production
hemolysin production

Question 5

What is responsible for the degredation of lactose?

Answer 5

lactose operon

Question 6

What is a good example of transcription initiation?

Answer 6

lactose operon

Question 7

What is the most common form of control of gene expression in bacteria?

Answer 7

negative regulation

Question 8

Lactose degredation involves how many enzymes?

Answer 8

three

Question 9

On a chromosome, where are structural genes located?

Answer 9

next to one another

Question 10

What are the three control genes in the lactose operon?

Answer 10

promoter
operon
regulatory gene

Question 11

In the lactose operon, what does the promoter do?

Answer 11

it is the region of DNA where RNA polymerase initiates transcription

Question 12

In the lactose operon, what does the operon do?

Answer 12

acts as traffic light for transcription of structural genes

Question 13

In the lactose operon, what does the regulatory gene do?

Answer 13

codes for repressor protein

Question 14

In the absence of lactose, what does the lac operon do?

Answer 14

operon gets repressed by binding of repressor protein to operator sequence

Question 15

What happens when lactose is present?

Answer 15

lactose binds to repressor protein and reverses the repression

Question 16

The operon is regulated by the product of the (blank)

Answer 16

regulatory gene

Question 17

What are the mutations you get with a single base change?

Answer 17

silent mutation

missense mutation

Question 18

What is a missense mutation?

Answer 18

a change in amino acid

Question 19

What is a silent mutation?

Answer 19

no change in encoded amino acid

Question 20

What are the mutations involved with changing numerous bases?

Answer 20

frameshift

null mutation

Question 21

What 2 ways can you get a null mutation?

Answer 21

• extensive insertion, deletion or gross rearrangement

- by recombination or genetic engineering

Question 22

What happens when you get a null mutation?

Answer 22

you destroy gene function

Question 23

Is mutation an efficient means for development of antibiotic resistance?

Answer 23

no!!! (because such a small mutation would never be able to incorporate enough DNA to cause resistance)

Question 24

What are the three ways you can get genetic exchange?

Answer 24

transformation
conjugation
tranduction

Question 25

What is transformation?

Answer 25

the uptake of naked DNA

Question 26

What is conjugation? | How does it work?

Answer 26

one-way direct cell-to-cell transfer of DNA through the sex pilus

Question 27

What is the common way for transfer of antibiotic resistance between species?

Answer 27

conjugation

Question 28

What is transduction?

Answer 28

transfer of genetic material via bacterial viruses

Question 29

Can you get transduction between very different species?

Answer 29

not really... its usually between the same or closely related species

Question 30

What is transformation?

Answer 30

uptake of naked DNA

Question 31

What does transformation require?

Answer 31

a competent cell

Question 32

What bacterial species can undergo transformation?

Answer 32

streptococcus pneumoniae | Neisseria gonorrhea

Question 33

Can you artificially cause transformation?

Answer 33

yes via electroporation or inducing changes in membrane permeability

Question 34

How is the naked DNA integrated into a chromosome in transformation?

Answer 34

via homologous recombination

Question 35

What is this: | one way transfer of DNA from a donor (male) cell to a recipient (female) through a sex pilus

Answer 35

conjugation

Question 36

What does conjugation require?

Answer 36

direct cell contact | F factor

Question 37

What is an F factor?

Answer 37

a special fertility factor found in the donor cell

Question 38

How is the F factor stably maintained?

Answer 38

within a plasmid

Question 39

WHat is a plasmid?

Answer 39

small genetic elements that can replicated indepenently of the bacterial chromosome

Question 40

What is an episome?

Answer 40

a plasmid that can integrate into the host chromosome

Question 41

How do you transfer the F factor in conjugation?

Answer 41

with the F plasmid and F pilus

Question 42

What does the F plasmid have within it?

Answer 42

all the genes necessary for its own transfer ability to make sex pilus ability to initiate DNA synthesis at the transfer origin of the plasmid

Question 43

When you the bacteria has an F plasmid does this make it male or female?

Answer 43

male

Question 44

During mating for conjugation what happens to the F plasmid?

Answer 44

it transfers its self make the recipient F+

Question 45

What does the F pilus do?

Answer 45

binds to recipient F- cell and brings pair in close proximity

Question 46

What is the F pilus made up of?

Answer 46

repeating units of a single protein called F pilin

Question 47

How do you make high frequency recombinant cell?

Answer 47

You get recombination b/w F factor and chromosome at a specific site and then insertion of F factor.

Question 48

Explain how to the transfer of chromosomal genes via F factor works

Answer 48

You have an Hfr cell and a F- cell. There is site specific cleavage at the replication origin (oriT), genes adjacent to F factor go into chromosome of recipient bacteria then F factor goes last.

Question 49

how can you manipulate bacteria into doing Hfr?

Answer 49

reciprocal recombination

Question 50

What was the first way to map genes?

Answer 50

via diruption of transfer at various time points in Hfr

Question 51

What can plasmids do?

Answer 51

give bacteria resistance, encode for toxins and attachment proteins, aid in metabolic pathways

Question 52

What can give bacteria resistance to many antibacterial compounds including heavy metas, mercurials and toxic anions?

Answer 52

plasmids

Question 53

What all can plasmids give bacteria resistance to?

Answer 53

antibiotics metals radiation bacteriophages

Question 54

What can plasmids create?

Answer 54

``` bacteriocins (compounds toxic for other bacteria) virulece factors (toxins, attachment proteins) ```

Question 55

What can plasmids participate in?

Answer 55

various metabolic pathways

Question 56

What do transposons do?

Answer 56

transfer DNA within a cell

Question 57

What are the 2 ways transposons can transfer DNA within a cell?

Answer 57

from one position to another in genome | between diferent molecules of DNA, e.g plasmid to genome

Question 58

What are simple transposons?

Answer 58

insertion sequence and transpoase gene

Question 59

What are insertion sequences?

Answer 59

inverted repeats that provide ends needed for recognition by transpoase

Question 60

(blank) is an enzyme that binds to the ends of a transposon and catalyzes the movement of the transposon to another part of the genome by a cut and paste mechanism or a replicative transposition mechanism.

Answer 60

Transposase

Question 61

Unlike homologous recombination, transposase does not require regions of (blank) for insertion

Answer 61

extensive homology

Question 62

What are complex transposons?

Answer 62

they include insertion sequences and carry additoinal genes (ie antibiotic resistance or toxin production)

Question 63

What are conjugal resistance plasmids?

Answer 63

They carry RTF (resistance transfer factor) that can carry drug resistant transposons :)

Question 64

Are conjugal resistance plasmids dangerous?

Answer 64

super dangerous!

Question 65

What is the abreviation for drug resistance tranposons?

Answer 65

r-determinant

Question 66

What does RTF (resistance transfer factor) do?

Answer 66

encodes genes needed for conjugal transfer

Question 67

What is the mechanism for multiple drug resistance (transposon component -r factor), mechanism for transfer to new bacteria (RTF) and if the plasmid carries multiple resistance genes, treatment with one antibiotic promotes resistance to multiple antibiotics?

Answer 67

conjugal resistance plasmid

Question 68

What is a bacteriophage?

Answer 68

it is a virus that infects bacteria

Question 69

What is transduction?

Answer 69

genetic transfer mediation by bacterial viruses (bacteriophages)

Question 70

How does transduction work?

Answer 70

During process of viral replication, portions of the bacterial chromosome may be packaged into the bacteriophage particle.

Question 71

What is generalized transduction?

Answer 71

Viral particles contain ONLY bacterial DNA It is random due to accidental packaging of host DNA (i.e virus destorys bacterial cell and accidently packages itsef with bacterial DNA and then infects a new bacteria and inadvertently gives that new bacteria the old bacterias skill set)

Question 72

What is specialized transduction?

Answer 72

Phage is in host cell and steals some of its genes and then leaves the cell and incorporates itself into the genome of a new cell so that the new cell (bacteria) now has the properties of the first cell. (this has both viral and bacterial DNA)

Question 73

T or F | Many bacterial virulence genes are encoded by temperate bacteriophage, e.g., diphtheria toxin

Answer 73

T

Question 74

So what is the lytic cycle?

Answer 74

When a phage enters a host cell and replicates to the point of killing the host cell

Question 75

What is the lysogenic cycle?

Answer 75

phage intergrates its DNA into bacterial chromosome and allows bacteria to reproduce normally thus replicating the viral DNA (on occasion the virus can excise from the bacterial chromosome and initiate a lytic cycle)

Question 76

Generalized transduction is one way for transfer of genetic information from one bacterium to another. Which of the following is a property of generalized transduction?

Answer 76

Transducing phage particles contain only bacterial DNA

Question 77

Transformation is the transfer of DNA from a donor to a recipient cell

Answer 77

As naked DNA in solution

Question 78

What is the most common means by which bacterial cells control gene expression?

Answer 78

Transcription control, most often via repressor proteins that block transcription