review

Question 1

what are the 4 types of horizontal gene transfer mechanisms?

Answer 1

Conjugation:
DNA acquired directly from another bacterium

Transformation:
DNA acquired from external environment (not from another organism)

Transduction:
DNA acquired from a bacteriophage

Extracellular vesicles:
DNA delivered by vesicle

Question 2

What is one thing that the donor needs in conjugation?

Answer 2

A conjugative mobile genetic element (MGE):
e.g. plasmid, genomic island, etc

Question 3

What does a conjugative MGE have?

Answer 3

• sex pilus genes
• mobility (MOB) genes

Question 4

Mobilizable MGEs (plasmids, genomic islands, etc) have _______ genes but DO NOT have _______ genes

Answer 4

Mobilizable MGEs (plasmids, genomic islands, etc) have MOB genes but DO NOT have sex pilus genes

Question 5

If a bacterium has a mobilizable MGE and a conjugative MGE:

Answer 5

• conjugative MGE produces sex pilus
• mobilizable MGE produces mobility proteins
• mobility proteins deliver mobilizable mGE to the sex pilus that was produced by the conjugative MGE
• mobilizable MGE is transferred to another cell

Question 6

If a bacterium just has a mobilizable MGE, this MGE ________ (can or cannot) be transferred to another cell through conjugation. Why?

Answer 6

If a bacterium just has a mobilizable MGE, this MGE CANNOT be transferred to another cell through conjugation (no sex pilus genes)

Question 7

What is a transformation pilus

Answer 7

basically a DNA uptake pilus

Question 8

Genomic islands are part of the bacterial chromosome that:
- was likely acquired through _______ gene transfer
- _________ (matches or does not match) the surrounding DNA (e.g. GC content)
- usually __________ (can or cannot) be transferred to other cells

Answer 8

Genomic islands are part of the bacterial chromosome that:
- was likely acquired through HORIZONTAL gene transfer
- DOES NOT MATCH the surrounding DNA (e.g. GC content)
- usually CAN be transferred to other cells (mobile genetic element)

Question 9

Genomic island encompasses many different kinds of mobile genetic elements such as:

Answer 9

• transposable elements
• a plasmid that was integrated into the chromosome (e.g, F factor)
• others not covered in this class

Question 10

Plasmid occur _________ the chromosome

a) inside
b) outside

Answer 10

b) outside

Question 11

genomic islands are __________ of the chromosome

a) a part
b) not a part

Answer 11

a) a part of the chromosome

Question 12

what are the types of genomic islands?

Answer 12

Conjugative genomic islands:
- encode everything needed to get cut out of chromosome, get transferred to another cell, and to insert into chromosome of that cell

Mobilizable genomic islands:
- Like mobilizable plasmids; don’t encode for conjugative machinery, but can use sex pilus produced by other MGEs

Question 13

Is a plasmid a genomic island?

Answer 13

Only if its integrated into the chromosome, otherwise no.

Question 14

What is monocistronic mRNA?

Answer 14

when there is only one gene between the promoter and the terminator it forms a short strand of mRNA that only contains one gene (one coding region) which is called a monocistronic mRNA

Question 15

If a ribosome stalls when translating mRNA, can this change the conformation of mRNA? How/how not ?

Answer 15

Yes. Where the ribosome is bound will change how the mRNA folds over itself.

Question 16

in order for translation to occur, the ribosome has to bind to the _____________, which is located where?

Answer 16

ribosome-binding site, which is located right before the start codon

Question 17

What do sequestors do in translation?

Answer 17

they basically hide the ribosome binding site so that translation cannot begin

Question 18

what do anti sequestors do in translation?

Answer 18

they prevent sequestors from forming

Question 19

what do anti anti sequestors do?

Answer 19

block anti sequestors from forming (therefore sequestor can form)

Question 20

what do genes in temporant phases undergo normally:

a) lytic cycle
b) lysogenic cycle

Answer 20

usually lysogenic

Question 21

What is an F+ cell vs an HFr cell vs an F- cell?

Answer 21

F+ cell has an F factor plasmid in the cytoplasm

HFr cell has the F factor plasmid integrated into the bacterial chromosome

and we can go from one to the other, and in reverse. But, when we go in reverse, the F factor might take up some of the chromosomal DNA trying to form the F+ cell again, and this would be called an F’ CELL.

The F’ still has all the sex factor genes and mobility genes, so it can still produce sex pilus and transfer this to other cells. The result of this is that the receiving cell also receives the F’ so its also now considered an F’ cell.