Bacterial Genetics and Toxins Flashcards
What is transformation?
- When bacteria pick up naked DNA
What prevents transformation?
Deoxyribonuclease
What bacteria can perform transformation?
SHiN
- Strep pneumoniae
- Haemophilus influenzae (type B)
- Neisseria
What is conjugation?
When DNA is transfered from one DNA to another via a pilus
What does F+ contain?
Sex pilus genes (F- does not)
What is high frequency recombination? (Hfr)
- A strain of bacteria that has incorporated an F factor into its chromosome and can then transfer the chromosome during conjugation
- When F+ genes are in F- cell’s chromosome it becomes a recombinant F- cell
What is transduction?
The sharing of viral DNA from one bacteria to another
What is the main difference between generalised and specialised transduction?
- Geralised the the sharing of pure DNA content into new bacteria via a bacteriophage
- Specialised transduction: bacteriophage with combination of both bacterial and viral DNA ‘unpure’ DNA transfers this to new bacteria
What phage is involved in specialised transduction and not generalised?
Lysogenic phage
- Incorporates viral DNA into bacterial chromosome - making ‘unpure’ DNA
- Also contains lytic phage where DNA is cleaved and viruses released
What type of transduction is rarer and creates a bacteria with different genes from donor and recipient?
Specialised
What 5 bacterial toxins are encoded in a lysogenic phage?
ABCD’S
- Group A strep
- Botulinum toxin
- Cholera toxin
- Diptheria toxin
- Shiga toxin
What is transposition?
When a DNA segment excises itself and inserts itself into the same DNA molecule or an unrelated DNA (e.g plasmid or chromosome)
What kind of toxins are only found on gram negatives?
Endotoxins (on outer cell membrane)
Exotoxins are found on both gram +ve and -ve
What is the structure of exotoxins?
Polypeptide
What is the structure of endotoxins?
Lipid A component of LPS
