COMMUNICABLE
DISEASES
___
INTRODUCTION
Bacteria are prokaryotes (no membrane-bound organelles)
Produce toxins that damage the host cell through :
● Breaking down the cell membrane
● Inactivating enzymes
● Interfering with genetic material and with cell division
Cell Structure
Less than 10 um
Basic shape :
- Rod = bacilli
, 2
- Spherical = cocci
- Comma = vibrios
- Spiralled = spirilla
- Corkscrew = spirochaetes
The cell wall in Gram staining can be depending on how it reacts with chemicals / with
antibiotics
- Gram positive = purple / blue
Eg. MRSA
- Gram negative = red
Eg. E. coli
VIRUS
Non-living
Much smaller than bacteria (few nm)
All natural viruses cause disease
Parasites (use animals/people as hosts)
Can only reproduce inside living cells and adapt quickly to them
BACTERIOPHAGE: invade bacterial cells
Cell Anatomy
DNA/RNA surrounded by a protein capsule
Takes over the metabolism and the genetic material of the host cell by
● inserting its viral DNA
● To reproduce
● New viruses burst out of the cell, destroying it and go on to infect other cells
Eg. Influenza, Tobacco mosaic virus
DISEASES
___
INTRODUCTION
Bacteria are prokaryotes (no membrane-bound organelles)
Produce toxins that damage the host cell through :
● Breaking down the cell membrane
● Inactivating enzymes
● Interfering with genetic material and with cell division
Cell Structure
Less than 10 um
Basic shape :
- Rod = bacilli
, 2
- Spherical = cocci
- Comma = vibrios
- Spiralled = spirilla
- Corkscrew = spirochaetes
The cell wall in Gram staining can be depending on how it reacts with chemicals / with
antibiotics
- Gram positive = purple / blue
Eg. MRSA
- Gram negative = red
Eg. E. coli
VIRUS
Non-living
Much smaller than bacteria (few nm)
All natural viruses cause disease
Parasites (use animals/people as hosts)
Can only reproduce inside living cells and adapt quickly to them
BACTERIOPHAGE: invade bacterial cells
Cell Anatomy
DNA/RNA surrounded by a protein capsule
Takes over the metabolism and the genetic material of the host cell by
● inserting its viral DNA
● To reproduce
● New viruses burst out of the cell, destroying it and go on to infect other cells
Eg. Influenza, Tobacco mosaic virus
