lecture 32 - microbial genetics Flashcards
What is the bacterial genome typically comprised of?
A single, circular chromosome.
Do bacteria have a nuclear membrane?
No
How is the chromosome of a bacteria contained?
It is restricted to a defined region of the cell called the nucleoid, that is not surrounded by a nuclear membrane
Where are plasmids found?
In the cytosol of bacteria
What is vertical gene transfer?
The transfer of genes from ‘parent’ to ‘offspring’ bacterial cells via binary fission/cell division.
What is horizontal gene transfer?
The transfer of genes between bacteria of the same generation, rather than to offspring
In horizontal gene transfer of bacteria, what component is the transferred gene usually held on?
The plasmid
What is pneumococcal disease?
A bacterial disease that has a smooth (fatal) strain and rough (non-fatal) strain
What is the structure and subsequent properties of the smooth strain of streptococcus pneumoniae?
bacteria has a polysaccharide capsule that protects it from phagocytosis
What is the structure and subsequent properties of the rough strain of streptococcus pneumoniae?
No polysaccharide capsule so can be readily phagocytosed by the body’s immune system
The capsule of streptococcus pneumoniae is an example of what type of selective advantage?
virulence factor
What are the 3 types of horizontal gene transfer in bacteria?
Conjugation, transduction, transformation
What is conjugation, in terms of bacterial horizontal gene transfer?
Transfer of nucleic acid from one bacterium to another via sexual pili
What is transduction, in terms of bacterial horizontal gene transfer?
Transfer of nucleic acids by phage viruses, who take up pieces of host bacteria DNA when undergoing the lysis, and then deposit it into different bacteria.
What is transformation, in terms of bacterial horizontal gene transfer?
The absorption of short fragments of naked DNA (e.g. from dead bacteria) by naturally transformable bacteria
