Microbiology 1-2 Flashcards
What are the three types of bacterial shapes?
Cocci (spherical, bacilli (rod-like) and spirilli
What does a gram stain distinguish between?
Gram negative and gram positive bacteria depending on whether peptidoglycan in present in the cell wall.
What colour will gram positive bacteria stain?
Deep violet due to thick peptidoglycan layer in the cell wall.
What colour will gram negative bacteria stain?
Pink as the layer of peptidoglycan is much thinner than in gram positive bacteria.
What is the structure of gram negative bacteria membranes?
Two membranes (plasma membrane and an outer membrane) with a periplasm of peptidoglycan in the middle.
What is the exception to gram negative and positive bacteria?
Mycobacteria - they have a waxy outer layer instead.
What is flagellum?
A highly complex structure made up of several proteins to facilitate proton-notice force needed for movement. It rotates and properly the bacteria to where it is needed.
What is an injectosome?
Structure evolutionarily related to flagellum that is involved in bacterial internalisation and actin polymerisation.
How large are bacterial genomes?
Big. Between 500 and 4500 proteins.
What percentage of bacterial genes are essential?
40%
What causes strains to be different from one another?
The 60% accessory genes.
How do bacteria replicate?
Binary fission
What is horizontal gene transfer?
Acquisition of genetic information by transfer from an organism that is not the parent and it not normally the same species.
What are the three mechanisms for horizontal gene transfer?
- Transformation (DNA uptake and homologous recombination)
- Conjugation (transmissible plasmid)
- Transduction (replication of bacteria and packaged into phages)
Examples of viruses that enter via the upper respiratory tract?
Influenza
Measles
Pneumonia
MRSA
