Bacterial Genetics and Virulence Factors

Question 1

We call the circular, extrachromosomal DNA of bacteria _

Answer 1

We call the circular, extrachromosomal DNA of bacteria plasmids
* We can sometimes find viral DNA that encodes bacteriophages inside bacterium

Question 2

Bacterial DNA is (haploid/diploid) and undergoes _ rather than reproduction

Answer 2

Bacterial DNA is haploid and undergoes clonal division rather than reproduction

Question 3

Tetracyclines (like doxycycline) are antibiotics taht target _ subunit of bacterial ribosomes

Answer 3

Tetracyclines (like doxycycline) are antibiotics taht target 30S subunit of bacterial ribosomes

Question 4

Before bacteria can undergo cell division, they must replicate; this is similar to eukaryotic replication except the DNA is much (shorter/longer) so the process is quicker, and replication begins from (one/multiple) ORIs

Answer 4

Before bacteria can undergo cell division, they must replicate; this is similar to eukaryotic replication except the DNA is much shorter so the process is quicker, and replication begins from one single origin of replication

Question 5

Helicase unwinds the DNA and then _ comes in to replicate the DNA strand and proofread

Answer 5

Helicase unwinds the DNA and then DNA pol III comes in to replicate the DNA strand and proofread

Question 6

Because prokaryotes tend to divide at a rapid rate (E.coli every 20 min), the process is prone to errors –> these lead to _

Answer 6

Because prokaryotes tend to divide at a rapid rate (E.coli every 20 min), the process is prone to errors –> these lead to spontaneous mutations
* This helps bacteria evolve

Question 7

_ are DNA sequences that contain protein-coding genes that allow transposition of DNA sequences within a genome

Answer 7

Transposons are DNA sequences that contain protein-coding genes that allow transposition of DNA sequences within a genome
* Transposons allow DNA sequences to jump from plasmid to chromosomal DNA and vice versa
* Factor in drug resistance
* A transposon sequence has to flank both sides of the gene of interest –> enzyme cleaves and ligates

Question 8

The three types of horizontal gene transfer are _ , _ , and _

Answer 8

The three types of horizontal gene transfer are conjugation , transformation , and transduction

Question 9

Bacteria join together in a process called _ ; only bacteria with a _ can undergo this

Answer 9

Bacteria join together in a process called conjugation ; only bacteria with a F plasmid can undergo this
* The F plasmid containd DNA that encodes for a sex pilus

Question 10

The F+ bacterium has a _ which connects to another bacterium that lacks the F plasmid

Answer 10

The F+ bacterium has a sex pilus which connects to another bacterium that lacks the F plasmid

Question 11

When the F+ and F- join, a _ forms and a single strand of the double-stranded F plasmid is transferred across

Answer 11

When the F+ and F- join, a mating bridge forms and a single strand of the double-stranded F plasmid is transferred across
* After, each bacterium synthesizes the necessary complementary strand and restores the double stranded plasmid

Question 12

The integration of an extrachromosomal DNA sequence into the bacterial chromosome at specific insertion sites is called _

Answer 12

The integration of an extrachromosomal DNA sequence into the bacterial chromosome at specific insertion sites is called site-specific recombination

Question 13

Plasmids that contain genes for resistance are called _

Answer 13

Plasmids that contain genes for resistance are called R factors or R plasmids
* The genes are called R determinants
* A single plasmid can contain multiple R determinant

Question 14

_ is the ability of the competent bacterial cells to take up the naked DNA from the environment; usually comes from lysed cells

Answer 14

Transformation is the ability of the competent bacterial cells to take up the naked DNA from the environment; usually comes from lysed cells
* Implementation of the absorbed bacteria into the host occurs through homologous recombination
* Ex: Streptococcus pneumoniae, Haemophilus influenzae type B, E. coli

Question 15

_ is when a bacterial cell becomes invaded with a bacteriophage or bacterial virus

Answer 15

Transduction is when a bacterial cell becomes invaded with a bacteriophage or bacterial virus
* Bacteriophage binds on the surface receptors and injects its DNA into the host

Question 16

(Generalized/ specialized) transduction is a packaging process, while (generalized/specialized) transduction is an excision process

Answer 16

Generalized transduction is a packaging process, while specialized transduction is an excision process

Question 17

In generalized transduction, some bacteriophages get packaged with _ rather than _

Answer 17

In generalized transduction, some bacteriophages get packaged with host bacterial DNA rather than viral DNA
* Gene swapping happens through homologous recombination

Question 18

During specialized transduction, a bacteriophage infects a bacterium and transfers _ , which gets incorporated into the host DNA forming a prophage

Answer 18

During specialized transduction, a bacteriophage infects a bacterium and transfers viral DNA , which gets incorporated into the host DNA forming a prophage –> the viral DNA becomes dormant –> gets passed on to daughter cells

Question 19

When induction occurs, the prophage DNA gets excised in a sloppy manner, taking along some of the _

Answer 19

When induction occurs, the prophage DNA gets excised in a sloppy manner, taking along some of the adjacent host DNA
* Now the next recipient will get the bacteriophage viral DNA and DNA from the previous host

Question 21

Staphylococcus aureus produces _ on its cell wall that binds to the Fc portion of human IgG and prevents the subsequent immune response

Answer 21

Staphylococcus aureus produces protein A on its cell wall that binds to the Fc portion of human IgG and prevents the subsequent immune response
* Recall that IgG normally functions to promote complement activation, opsonization, and phagocytosis

Question 22

S. pneumoniae, Influenzae type B, and Neisseria produce _ protein that binds and degrades IgA antibodies

Answer 22

S. pneumoniae, Influenzae type B, and Neisseria produce IgA protease that binds and degrades IgA antibodies
* Recall that IgA normally prevents pathogens from attaching to the mucuous membranes
* IgA is mostly found in the respiratory mucosa

Question 23

_ protein prevents phagocytosis by preventing opsonization by binding to fibrinogen

Answer 23

M protein protein prevents phagocytosis by preventing opsonization by binding to fibrinogen
* This forms a dense fibrillar barrier on the bacterial surface that interferes with C3b deposition
* Also induces an auto-immune like response due to cross-reactivity
* ex: Streptococcus pyogenes

Question 24

Rheumatic fever is a compliation to group A streptococcal infection that progresses from strep throat; it causes polyathritis, carditis, nodules, etc; this happens because the _ protein is a similar structure to human cellular proteins –> causes antibodies to be produced which inadvertently react with host cells

Answer 24

Rheumatic fever is a compliation to group A streptococcal infection that progresses from strep throat; it causes polyathritis, carditis, nodules, etc; this happens because the M protein is a similar structure to human cellular proteins –> causes antibodies to be produced which inadvertently react with host cells