Bacteria
Good …or Evil?
What are bacteria?
• Single-celled organisms that lack a nucleus
• Prokaryotes – an organism whose cells lack
a nucleus and some other cell structures.
• The genetic material in their cells is not
contained in a nucleus.
Cell Structures
Bacteria Cell structures (cont.)
cell wall - A thin membrane located outside the plasma
membrane and within the capsule.
plasma membrane - A permeable membrane located
within the cell wall. It serves many functions for the cell,
including energy generation and transport of chemicals .
Bacteria cell structures (cont.)
cytoplasm - The jellylike material inside the plasma membrane in
which the genetic material and ribosomes are located.
DNA - The genetic material of the bacterium; it is located within the
cytoplasm.
ribosomes - Small organelles composed of RNA-rich granules that are
sites of protein synthesis. The ribosomes are located within the
cytoplasm.
Bacteria cell structures (cont.)
• flagellum - A long whip-like structure used for locomotion
(movement). Some bacteria have more than one flagellum.
3 Basic Cell Shapes
What do bacteria need to
survive?
•Food
•Energy
A Bacteria’s Diet:
• Bacteria have a wide range of diets.
• heterotrophs (they eat other organisms)
Most heterotrophic bacteria are saprobes (they absorb
dead organic material like rotting flesh).
• autotrophs (they make their own food).
Autotrophic bacteria make their own food, either by
photosynthesis (which uses sunlight, carbon dioxide and
water to make food) or by chemosynthesis (which uses
carbon dioxide, water and chemicals like ammonia to
make food .
Respiration (Energy)
• Process of breaking down food to release energy.
Bacterial Reproduction
http://www.youtube.com/watch?v=gEwzDydciWc
How do Bacteria Reproduce?
Asexual Reproduction:
Binary fission
only one parent
offspring identical to parent
http://www.youtube.com/watch?v=DY9DNWcqxI4
How do Bacteria Reproduce?
Sexual Reproduction:
Conjugation
2 parents
combine genetic material to produce new
organism
does not increase number of bacteria
results in new bacteria, genetically different than
parents
http://www.youtube.com/watch?v=7stZk6TesKk
What are Endospores?
• Bacteria in “hibernation”, taking a rest
• Endospores are small rounded, thick-walled, resting cell
that forms inside a bacterial cell.
• It contains the cell’s genetic material and some of its
cytoplasm.
• When conditions are suitable, it opens up. Then the
bacterium can begin to grow and multiply.
Bacteria: Good or evil?
Evil: They make us sick
Good: involved in oxygen and food production
environmental recycling and cleanup
health maintenance and medicine production