Plasmids

Question 1

What is a plasmid?

Answer 1

Double-stranded, circular, closed DNA with sizes between 1-200 kb
Extra-chromosomal genetic components

Question 2

What do they code for?

Answer 2

Enzymes that are advantageous to the bacterial host

Question 3

Properties as cloning vector:

Answer 3

Small and replicate at a relaxed manner

Question 4

Properties as cloning vector:

Answer 4

Contain single recognition site for one or more restriction enzymes on regions not essential for replication

Question 5

Properties as cloning vector:

Answer 5

Restriction sites, where foreign DNA is inserted, are within genes coding for selective markers so that when foreign DNA is inserted, it inactivates the gene

Question 6

Properties as cloning vector:

Answer 6

Contain one or more selectable markers to enable one to know the transformed cells and maintain plasmid in bacterial population

Question 7

Phenotypes conferred by plasmids:

Answer 7

• antibiotic resistance
• production of antibiotics
• production of colicins
• production of enterotoxins
• production if restriction and modification enzymes
• degradation of complex organic compounds