Genetics and Growth of Prokaryotic Cells

Question 1

Binary fission

Answer 1

A simple form of asexual reproduction seen in prokaryotes. The circular chromosome attaches to the cell wall and replicates while the cell continues to grow in size

Question 2

Virulence factors

Answer 2

Traits that increase pathogenicity, such as toxin production, projections that allow attachment to certain kinds of cells, or features that allow evasion of the host’s immune system –> carried by plasmids

Question 3

Episomes

Answer 3

A subset of plasmids, capable of integrating into the genome of the bacterium

Question 4

Genetic recombination process in bacteria

Answer 4

Transformation, conjugation, and transduction

Question 5

Transformation

Answer 5

Results from the integration of foreign genetic material into the host genome.
Usually bacteria, upon lysing, spill their contents into the vicinity of a bacterium capable of transformation.
Many gram-negative rods are able to carry out this process

Question 6

Conjugation

Answer 6

The bacterial form of mating (sexual reproduction).

Involves 2 cells forming a conjugation bridge between them that facilitates the transfer of genetic material

Question 7

Method of conjugation

Answer 7

Transfer is unidirectional, from donor male (+) to recipient female (-). Bridge is made from appendages called sex pili found on donor male. To form pilus, bacteria must contain plasmids known as sex factors that contain the necessary genes.

Question 8

F (fertility) factor

Answer 8

Best-studied sex factor in E. coli. Bacteria containing it are F+ cells, those without are F- cells.

Question 9

How does F factor get passed on

Answer 9

During conjugation the F+ cell replicates its F factor and donates the copy to the F- cell, converting it to an F+ cell. This enables the cell with new copy to transfer more copies to other cells.

Question 10

what is the process of Hfr/ high frequencey of recombination

Answer 10

Refers to cells that have undergone the following change:
sex factor gets integrated into host genome.
When conjugation occurs, entire genome replicates because it now contains the sex factor.
Donor cell will attempt to transfer an entire copy of its genome into the recipient; however, the bridge usually breaks before full DNA sequence can be moved

Question 11

Transduction

Answer 11

Requires a vector – a virus that carries genetic material from one bacterium to another.

Question 12

How does transduction work

Answer 12

Bacteriophages (viruses that infect bacteria) can accidentally incorporate a segment of host DNA during assembly. When the bacteriophage infects another bacterium, it can release this trapped DNA into the new host cell.
Transferred DNA can then integrate into teh genomre, giving the new host additional genes

Question 13

Transposons

Answer 13

Genetic elements capable of inserting and removing themselves from the genome –> seen in prokaryotes and eukaryotes

Question 14

Stages of bacteria growth

Answer 14

lag, exponential/log, stationary, and death phase

Question 15

Lag phase

Answer 15

In a new environment, bacteria first adapt to the new local conditions during this phase

Question 16

Exponential/log phase

Answer 16

As bacteria adapt, rate of division increases, causing an exponential increase in the number of bacteria in the colony in this phase

Question 17

Stationary phase

Answer 17

As number of bacteria in the colony grows, resources are often reduced –> this reduction of resources slows reproduction

Question 18

Death phase

Answer 18

After bacteria have exceeded the ability of the environment to support the number of bacteria, death phase occurs, marking depletion of resources