Bacteria and VirusesBrought to you by Mr. Brinkman
Taxonomy• The branch of biology dealing with the
classification of life.• 1700s 2 kingdoms: plant and animal• 1800s 3 kingdoms: plant, animal, and
protista• 1950-1990s 5 kingdoms: plant, animal,
protista, fungi, monera• Present: 6 kingdoms: eubacteria,
archaebacteria, protista, animal, plant, fungi
Prokaryotes
• Traditionally all prokaryotes
• Presently, the prokaryotes are divided into two kingdoms.– Archaecbacteria– Eubacteria
Eubacteria• Larger of the two kingdoms• Live almost everywhere• Vital for life functions and
industry• Both helpful and harmful
Archaebacteria• Comes from the Greek word
archaio which means “ancient”• Believed by many to be the earliest
organisms to inhabit the earth• All live in harsh environments• 3 separate phyla:
1. Methane-producing bacteria (methanogens)• Intestinal tracts
of animals• Bottoms of
swamps• Used for
sewage treatment
2. Salt-loving bacteria (Halophiles)
• Thrive in high salinity waters where no other life can exist.
• Great Salt Lake
• Dead Sea
3. Hot-acidic loving (thermoacidophiles)• Thrive at
temperatures as great as 180ºF and pHs as low as 2.
• Natural springs.• Yellowstone
National Park
Facts about bacteria:• Found everywhere• Very small. Much smaller than any
cell in our body.• No membrane-bound structures or
nucleus. (prokaryotes)• Usually surrounded by a cell wall
and a capsule for additional protection.
General structure:
Classification according to shape.1. Coccus (spherical)
Can be single cells
Pairs
Chains
2. Bacillus (rod)• Single cells• Pairs• Chains
• example– anthrax
3. Spirillum(spiral)
Only exist as single cells
Example:cholera, syphillis
Shapes:
Metabolic Needs• Aerobic• The most common type• Cannot live without oxygen
• Anaerobic• Cannot live in the presence of
oxygen• Gets energy through fermentation
(CO2)
Heterotrophic bacteria• Decomposer• Feed off the remains of dead
plants and animals. Seldom cause disease
• Parasites• Live on or in other living
organisms. Often cause disease
Autotrophic bacteria• Photoautotroph• Use sunlight to convert carbon
dioxide into energy• Ex. cyanobacteria
• Chemoautotroph• Use inorganic chemical compounds
to convert carbon dioxide into energy.
Genetic material• Nucleoid= a
single circular chromosome containing the DNA and RNA.
• Endospore = tough protective coat that covers and protects the nuclear material.
Reproduction• All reproduce asexually
• Usually through binary fission
• Under certain conditions, bacteria can reproduce very quickly–A small colony can double in 20
minutes.
Binary fission• The most
common type of asexual reproduction.
• A single cell splits to form two daughter cells
Exchange of DNA Conjugation
= genes move from one cell to another
Endospores• A thick covering
around the DNA that allows the bacterium to remain dormant for long periods of time. If necessary, many years.
Helpful bacteria• Decompose food wastes• Produce vitamins• Produce antibodies• Genetic engineering• Decomposition of dead plants and
animals• Industry & agriculture
Plant roots• Found on the
roots of plants. • Can be helpful
in ‘fixing’ nitrogen for plant use.
• Rhizobium nodules on roots of soybeans
VIRUSES
• Are they living or non-living?• Contain genetic material• Lack organelles
Cannot reproduce unless inside a host cell.
• The word virus comes from the Greek word for POISON
• Cause many diseases.
How big is a virus?• Much smaller than
bacterial cells.• Scientists have
only recently, last 60 years, learned anything about viruses
• Classified according to the types of cells they attack.
Virus structure:• A center core of DNA or RNA
surrounded by a protein coat called a capsid.
2 main types of viral reproduction:• LYTIC CYCLE1. Injects its nucleic acid (DNA or
RNA) into the cell to take over cellular activities.
• LYSOGENIC CYCLE1. Coexists with the cell without
destroying the host cell
Lytic cycle
Lysogenic cycle
RETRO-VIRUS
• Direct the production of proteins by the host cell.
• RETROVIRUS = A special type of virus that can make DNA which will produce new RNA, which, in turn, makes proteins that produce new viruses.
• Ex. AIDS VIRUS
Diseases caused by microorganisms:• Pathogens: disease-causing
agents• BACTERIAL DISEASE:1) Damage cells and tissues
directly2) Release toxins to interfere
with normal cellular activity
Common bacterial diseases:• LymeS disease• Tetanus• Strep throat• Tuberculosis• E. coli poisoning
Controlling bacterial disease.• ANTIBIOTICS• 1928. Discovery
of penicillin by Sir Alexander Flemming
• Came from a mold.
Common methods of bacterial infection.• Food & water
(E. coli)• Coughing &
sneezing• Sexually
transmitted.• Carried by
insects
Food disease prevention• Keep hands, and cooking utensils clean
• Canning and preservation techniques with food.
• Pasteurization• Freezing
How do we prevent viral diseases?
• Cannot be treated with ordinary antibiotics
• Vaccinations. The word comes from the vacca Latin for “cow”.
• A vaccine is a weakened form of a virus that is used to stimulate the immune system to produce antiviral substances.
Edward Jenner (1749-1823)• British
physician• Developed the
first vaccine in 1798 for the viral disease smallpox.
• Considered the “Father of Immunology”
Common viral diseases:• AIDS• Measles• Chickenpox• Smallpox• Influenza• The common cold• West Nile• Polio
SMALL POX
• Viral disease that is believed to have originated in Egypt at least 2000 years ago.
• Characterized by pox lesions and boils.
• Spread to the Americas by Spanish conquistadors.
• Jenner’s vaccine was developed after observing a bovine disease: “cowpox”
Eradication of smallpox:Or is it?• In 1967 the World Health
Organization launched a global effort to eradicate smallpox.
• 1978 : Last known case of smallpox.
• 1980 : W.H.O. declares the world free of smallpox.
• Is there any smallpox virus left?
Viroids and Prions• Viroid• Small disease causing
particle.• Affect plants
• Prion• Small disease causing particle.• Affects animals.• example:
MAD COW DISEASE