Download What are Bacteria?

What are Bacteria?
Chapter 7, Section 1
What is a Bacterium?
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
One-celled organism.
Prokaryotic.
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(Do not have membrane bound nuclei or
organelles.)
Can live alone or in groups or chains.
Smaller than plant and animal cells.
Who discovered bacteria?

Antonie van Leeuwenhoek (in the later
half of the 17th century).
Where do Bacteria Live?
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Everywhere!
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Including, the soil, the air, your body,
deep sea, hot springs, food…
What does a Bacterial Cell
look like?
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3 basic shapes:
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Cocci – sphere-shaped bacteria
Bacilli – rod-shaped bacteria
Spirilla – spiral-shaped bacteria
What does a Bacterial Cell
look like?
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Typical Cell
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Cytoplasm surrounded by both a cell
membrane and a cell wall.
One circular chromosome (genetic
material).
Ribosomes
What does a Bacterial Cell
look like?

Some Cells:
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Plasmid (smaller circular piece of DNA)
Thick, gelatin-like capsule
Hair-like projections on cell surface
Slime layer (on outside)
Flagella (whip-like tail)
How do Bacteria Reproduce?
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Asexually
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Fission
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Produces two new cells with genetic material
identical to the original cell.
Sexually
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Conjugation
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Two bacterial line up next to each other and
then exchange DNA through a fine tube.
Result is new combinations of genetic
material.
How do Bacteria Obtain Food
and Energy?
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Producers
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Use the sun to make food.
Break down chemicals to make food.
Consumers (majority of bacteria)
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Break down dead organisms.
Parasitic.
How do Bacteria Obtain Food
and Energy?
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Aerobic Bacteria (most bacteria)
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Use oxygen during respiration to break
down food.
Anaerobic Bacteria
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Do not need oxygen in order to survive.