Transcript Bacteria Powerpoint #2

Kingdom Monera – Bacteria
Characteristics and Diversity
www.onacd.ca
Bacteria were first
identified in 1677 by
Antonie van
Leeuwenhook after
he developed a
primitive version of
the compound
microscope.
He originally called all
single celled
organisms he had
discovered
“animalcules” and
they were later
separated into
groups, one of which
included bacteria.
A few bacteria that cause human disease
Salmonella bacteria (red) :
causes Salmonella poisoning
E.Coli bacteria
Helicobacter pylori: can
cause ulcers, stomach
cancer…
Tetanus bacteria
Bacterial Shapes
Bacterial shape influence the ability of
the bacteria
-to attach to surfaces
-acquire nutrients
-move through liquids
-escape predators
Bacteria are found in three distinct shapes
Rod shaped : Bacilli
ex. Anthrax (Bacillus anthraxis) & Tetanus (Clostridium tetani)
2. Spherical shaped
Can be found as single cocci, pairs (diploid),
chains, or clumps
Single cocci
2. Spherical shaped
Can be found as single cocci, chains, or
clumps
Diploids – pairs of spherical shaped bacteria
ex. Neisseria (can cause gonorrhea, bacterial meningitis
& septicemia)
Bacterial
meningitis
Neisseria : gonorrhea
2. Spherical shaped
Chains of spherical shaped bacteria
ex. Streptococcus ( cause a variety of human disease
including meningitis, flesh eating disease, and bacterial
pneumonia)
2. Spherical shaped
Chains of spherical shaped bacteria
ex. Streptococcus ( cause a variety of human disease
including meningitis, flesh eating disease, and bacterial
pneumonia)
2. Spherical shaped
Clusters of spherical shaped bacteria
ex. Staphylococcus aureous (can cause a variety of
human infections including skin infections, Toxic Shock
Syndrome, meningitis….)
3. Spiral shaped
Actually are a form of rod
shaped bacteria
Leptospirillum
Bacterial Structure
Example: bacillus structure
Internal cell structures
Surrounded by a cell membrane
• Acts as a barrier and holds in proteins and other
parts of the cytoplasm
• Allows for transport of energy and materials across
it via a concentration gradient
Single ring of genetic material (chromosome)
encased in a nucleoid
External cell structures
Cell Wall
• Composed of peptidoglycan (as opposed to cellulose in plant cells)
• Two types
• Gram positive – have a thick cell wall
• Gram negative – have a thin cell wall and most bacteria fall into this
category
• Important in antibiotic use as antibiotics affect the ability to produce a cell
wall
Flagella
• Used for motility and are driven by energy
• Can be found alone, at each end, in clusters at the poles or all over the cell
Pili (sing. Pilus)
• Used for transferring genetic material between cells
Fimbriae
• Fine filaments of protein that aid in the attachment to other cells
Specialized External Structure:
Endospore:
-adaptation to survival during unfavorable conditions
-form dormant or resting cells
-resistant to severe physical and chemical stresses
-simply constructed of a central core of DNA that is surrounded by an
impenetrable layer
- can remain viable for millions of years
-are capable of causing some serious diseases:
ex. Anthrax (Bacillus anthraxis) & Tetanus (Clostridium tetani)
Bacteria have recently been classified by the
environment that they live in
1. Archaebacteria – live in an environment
without oxygen
2. Eubacteria – live in an environment with
oxygen
(archae= old)
(eu= true)
Bacteria can also be grouped according to
their type of respiration
•
•
•
Obligate aerobes – must have oxygen to survive
Obligate anaerobes – can only grow in the
absence of oxygen
Facultative anaerobes – prefer environments with
oxygen but can live in environments without
oxygen
Nutrition: How do bacteria get the food
(carbon) and energy they need to survive?
Some are autotrophs (collect their own energy)
Photosynthetic - use of light for energy
Chemosynthetic – use of chemical substances for energy
Some are heterotrophs (obtain food from other sources)
Saprophytic (obtain raw materials from dead and
decomposing matter)
Parasitic
Symbiotic / mutualistic (ex. Bacteria in the human colon)
Some are chemotrophs (perform fermentation)
Modes of Bacterial disease transmission
• Direct contact
• Airborne droplets
• Bacterial toxins in
food (ingestion)
• Fecal contamination
of food
• Water
• Vector bites (ex.
Mosquito)