Download Chapter 7: Bacteria

Aim: What are the characteristics
of bacteria?
Bacteria
 Antonie van Leeuwenhoek discovered bacteria
 Are in the air, foods, surfaces of things we
touch
 Found underground and at the great depths of
the oceans
 Lives in your body
 Some like extreme temperatures-live in hot
springs
 Others live in cold water, or acidic water, or
salty water
Structure of Bacteria
 Smaller than plant or animal cells
 One-celled that occur alone, in chains or
groups
 3 basic shapes:
1. Spheres:

Called cocci
2. Rods:
 Called bacilli
3. Spirals
 Called spirilla
 Contains cytoplasm surrounded by cell
membrane and a cell wall
 Prokaryotic-no membrane-bound organelles and
nucleus
 Genetic material is located in the one circular
chromosome
 Ribosomes found in cytoplasm
Special Features
 Some bacteria has a thick, gelatinlike capsule
around the cell wall
 Helps protect the bacteria from being
destroyed
 Helps it stick to surfaces
 Some have hairlike projections on its surface
 helps them stick to surfaces
 Slime layer also helps them stick
 Those who live in moist places have a flagella
 Helps them move
Aim: How do bacteria reproduce
and obtain energy?
Reproduction
 Reproduces by fission
 Simplest form of asexual reproduction
 2 new cells with genetic material identical to the
original cell are produced
 Some reproduce through a process similar to
sexual reproduction
 2 bacteria line up next to each other
 Exchange DNA through a tube
 Results in cells with different combinations of
genetic material-may give them an advantage on
surviving
Obtaining Food and Energy
 Some make their food
 Contain chlorophyll and use the Sun’s energy
 Others use energy from chemical reactions
 Called producers
 Some get it from their environment
 Most are consumers
 Break down dead organisms
 Live as parasites
 Aerobe-uses O2 for respiration
 Most bacteria are aerobes
 Anaerobe-is adapted to live without O2
 Several kinds of this bacteria live in the
digestive tract of humans
 Some can’t survive in areas with O2
Aim: What is the difference
between Eubacteria and
Archaebacteria?
Eubacteria
 Grouped according to their:
 cell shape
 structure
 way they obtain food
 type of food they consume
 Wastes they produce
 Method used for cell movement
 Whether its an aerobe or anaerobe
 Some are producers
 Cyanobacteria
 Make their own food used CO2, water, and
energy from the sun
 Produce oxygen as a waste
 Contain chlorophyll and a blue pigment
 Known as blue-green bacteria
 Some are yellow, black or red
 live together in long chains or filaments
 Many covered with gelatinlike substance-able
to live in colonies
 Are an important source of food for some
organisms
 Can cause problems for aquatic life
 Some are consumers
 Grouped based on whether they are gram-
positive or gram-negative
 Composition of the cell wall can determine
how it will react to antibiotics
Archaebacteria
 Found in extreme conditions, such as hot
springs
 One of the first organisms on Earth
 Grouped based on
 Where they live
 How they get energy
 Some live in salty environments
 Some live in acidic or hot environments
 Some are methane producers
 Live in muddy swamps, intestines of cattle
and humans
 Anaerobic
 Use CO2 for energy
 Release methane as a waste
 Used to breakdown sewage material
Aim: How can bacteria be helpful?
Benefits of bacteria
 Some bacteria is responsible for producing
vitamn K- necessary for blood clotting
 Some help digest food in the large intestine
 Some produce antibiotics
 Bacillus produces antibiotic found in
antiseptic ointments
 Bacterial found in the soil produces
streptomycin
 Some are saprophytes- help recycle nutrients
 Used in sewage plants to break down wastes
in CO2 and H2O
 Nitrogen-fixing bacteria
 Change nitrogen in the air to forms that
plants and animals can use
 Animals and plants need nitrogen to make
proteins and nucleic acids
 Saves farmers millions of dollars in fertilizer
 Bioremediation-using organisms to help clean
up or remove environmental pollutants
 Uses bacteria to breakdown wastes and
pollutants into simpler harmless compounds
 Other bacteria use certain pollutants as a
food source
 Only 5%-10% of wastes are treated through
this process
 Scientists researching to make it faster
 Used in the production of foods
 Yogurt
 Cheeses
 Sauerkraut
 Soy sauce
 pickles
 Used to make medicines, enzymes, cleansers
and adhesives
 Methane gas that is released by many bacteria
can be collected and used as fuel
Aim: How can bacteria cause
human diseases?
Harmful Bacteria
 Pathogens-any organism that causes disease
 Bacterial pathogens can cause illness and
disease
 Enter through cut in the body, or inhale them
 Once in your body they multiply
 Some produce toxins-Ex: Botulism
 Some bacteria have endosperms that enable
them to adapt to harsh environments
 All food contains bacteria unless it was
sterilized
 One way to kill bacteria is through
pasteurization
 Usually treated with antibiotics
 Example: penicillin
 Vaccines can prevent bacterial diseases