Lack a nucleus; nuclear material in the cytoplasm.
Bacteria are prokaryotic organisms.
Bacteria
Microscopic, single-celled.
Have a cell wall, cell membrane, cytoplasm, and plasmids.
Lack a nucleus but contain circular DNA.
Lack mitochondria and other membrane-bound organelles.
*Examples: Lactobacillus, Pneumococcus.
Some perform photosynthesis despite lacking chloroplasts.
Most feed on other living or dead organisms (saprobionts or decomposers).
Cell Component Comparison:
Component
Eukaryotes
Prokaryotes
Cell membrane
Y
Y
Cytoplasm
Y
Y
Genetic material
Y - in a nucleus
Y - in the cytoplasm
Nucleus
Y
N
Cell wall
Some types
Y
Pathogens
A pathogen is a microorganism that causes disease.
Types of Pathogens:
Bacteria
Fungi
Protoctists
Viruses
Pathogenic Bacteria
Don't always infect host cells; can remain in body cavities.
M. tuberculosis: Causes tuberculosis (TB) in humans.
Infects lungs, causing chronic cough and bloody mucus.
Associated with poor hygiene and sanitation.
M. bovis in cows can transmit to humans.
Pathogenic Fungi
More common in plants.
Cattle ringworm and athlete's foot are fungal diseases on the skin surface.
Black Sigatoka: Fungal disease in bananas.
Spreads through leaves, reducing photosynthesis.
Causes leaf parts to die; producing black streaks.
Pathogenic Protoctists
Plasmodium falciparum: Causes severe malaria in humans.
Spread by mosquitoes.
Causes fever, chills, and fatigue.
Viruses
Not usually classified as living organisms; don't carry out all life processes independently.
Only life-process they seem to display is reproduction but even to carry out this process they must take over a host cell’s metabolic pathways in order to make multiple copies of themselves.
Small particles.
Parasitic.
Infect every type of living organism.
Lack cellular structure but have a protein coat and contain DNA or RNA.
Tobacco mosaic virus (TMV): Discolours tobacco leaves, reduces photosynthesis, spread by direct contact and soil contamination, no treatment.
HIV: Leads to AIDS, attacks immune system, spread by sexual contact/bodily fluids/mother to child, controlled by antiretroviral drugs.