Bacteria
BACTERIA
• Prokaryotic
• Cell wall, cell membrane, cytoplasm
• DNA = in cytoplasm or as a plasmid (circular piece
of DNA)
• Smallest form of life
• Found everywhere
Shapes of Bacteria
Bacteria can obtain their energy in different ways:
Autotrophs
Chemotrophs
Heterotrophs
Decomposers
- Make own food
- Make food from inorganic compounds
- Obtain food from other organisms
- Feed on dead materials
Bacteria live in a variety of conditions:
Obligate Anaerobes
Obligate Aerobes
Facultative Anaerobes
- Do not require oxygen
- Require oxygen to live
- Can exist with or without O2
Bacterial Reproduction
In favorable conditions, bacteria can grow and divide
every 10-20 mins
• Bacteria divide into two bacteria cells = binary
fission
• Some bacteria can exchange genetic material =
conjugation
Video = Youtube
Nitrogen
Bacteria in soil that can convert nitrogen gas
into amonia for plants to use = nitrogen
fixation
Anaerobic bacteria in soil eventually return
nitrogen back to the atmosphere = nitrogen
cycle
Probiotics vs. Antibiotics
Some bacteria are good and others are bad...
E. coli that lives in your intestinal tract, is needed to
help digest food
Probiotics help promote the growth of bacteria
Antibiotics are chemicals that kill bacterial cells or
slow down growth
Viruses
VIRUS
• Non-living
• Structure = protein capsid, genetic
material, tail fibers, tail sheath
• "Lock and key" attachment = fits with the
host cell
• Two reproductive cycles: Lytic or
Lysogenic
• Both require a living host
Lytic Cycle
Virus injects DNA into the cell & takes over the cell to
make more viral DNA
Lysogenic Cycle
Virus injects DNA into cell which then fuses with cells
DNA
Immune System
HUMAN IMMUNE SYSTEM
• 1st Line of Defense
• Integumentary system (skin, sweat, oils, tears, mucus)
• 2nd Line of Defense
• Inflammatory response (and fever)
• Specific Immunity
• Recognize cells as healthy / unhealthy
• Antigens trigger immune response
• Cellular Immunity - T-cells (helper, killer & memory) [WBC]
• Antibody Immunity - B-cells (memory and antibodies)
• HIV - attacks T cells
• Vaccines - acquired immunity
Immunity
• Innate immunity = born with
• Acquired immunity = once exposed to a pathogen, the
body learns
• Immune system works with the integumentary system &
circulatory system to block & prevent invaders from
harming the body
• Fevers causes WBCs to mature faster & creates an
unfavorable environment for invaders
• Vaccinations = prevent disease / jump start to the immune
system