Transcript Cell Biology Chapter Nine: The Microscopic World • 9.1 Protozoans • 9.2 Bacteria • 9.3 Viruses.

Cell Biology
Chapter Nine: The Microscopic
World
• 9.1 Protozoans
• 9.2 Bacteria
• 9.3 Viruses
Investigation 9B
Investigating
Pond Water
• Which
microscopic
organisms are
found in pond
water?
9.2 Bacteria
• Bacteria are organisms
that consist of a single,
prokaryotic cell.
• Bacterial cells have a
cell membrane that is
surrounded by a tough
cell wall.
Bacteria can live in soil,
water or air.
9.2 Size and shape of bacteria
• Bacteria are not easy
to measure using
meters, centimeters,
or even millimeters.
• Micrometers (μm)
are used to measure
them.
Bacteria are much smaller
than most other cells.
9.2 Size and shape of bacteria
• Bacteria are identified based on the shape of
their cells.
• Rod-shaped bacteria are
called bacilli.
• Ball-shaped bacteria are
called cocci.
• Spirilla are spiral-shaped
bacteria.
Bacilli in your intestine
help with digestion.
9.2 Movement and feeding
• Bacteria get around in
many ways.
– Some bacteria move
using flagella.
– Others have a slimy
layer to grip surfaces.
– Some are carried by the
movement of air or
.
liquids.
9.2 Movement and feeding
• Photosynthetic
bacteria can make their
own food from sunlight
and carbon dioxide, just
like plants.
• Bacteria that break down
dead organisms get their
food by absorbing it.
These blue green
bacteria use sunlight
to make food.
9.2 Bacteria and the
beginning of life
• Scientists believe that bacteria were the first
organisms on Earth.
9.2 The importance of bacteria
• Bacteria are useful in many areas of industry.
– Yogurt and cheese are made with certain types of
bacteria.
– Bacteria break down waste products in sewage.
– Bacteria can help clean up oil spills.
• Bacteria also cause diseases:
– strep throat
– respiratory infections
– infected wounds
9.2 The importance of bacteria
• Bacteria are an
important part of
the nutrient cycles
that all life depends
upon.
9.2 The importance of bacteria
• Bacteria are
“nature’s recyclers.”