Microbial Genetics

Question 1

Describe both vertical and horizontal gene transfer

Answer 1

Vertical gene transfer: from ‘parent’ to ‘offspring’
Horizontal gene transfer: directly from one organism to another

Question 2

What are the two important attributes transferred horizontally by bacteria

Answer 2

• Virulence factors: attributes that help bacteria survive in the host, sometimes at a cost to the host. A good example are the capsules of streptococcus pneumonia
• Antibiotic resistance: Attributes that reduce the effectiveness of antibiotics against the targeted bacteria. A good example s the plasmid carrying Beta-Lactamase enzyme which inactivated penicillin.

Question 3

What are the three horizontal gene transfer strategies (and outline what they are)?

Answer 3

• Transformation: DNA from dead or dying bacteria are released into the body/environment. They will then enter live bacteria and transform it into something else
• Transduction: Bacteriophage sits on bacteria and injects its DNA into it. That DNA will then replicate inside the cell and eventually the cell will burst and release lots of new bacteriaphages
• Conjugation: Involves a ‘sex pilus’ where plasmids from one bacteria are sent through the tube to the other bacteria

Question 4

What is phage therapy?

Answer 4

The therapeutic use of bacteriophages (viruses that specifically kill bacteria) to treat pathogenic bacterial infections.