Bacteria and Viruses

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Chapter 7

• Bacteria and Viruses

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Chapter 7

• Lesson 1
• What are Bacteria?

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Lesson 1
Characteristics of Bacteria

• Bacteria are microscopic prokaryotes (they do
  not have a nucleus).
• Bacteria live in almost every habitat on Earth
  and in or on almost every organism, both living
  and dead.

bacteria from Greek bakterion, means small staff
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Lesson 1
Characteristics of Bacteria (cont.)

• A typical bacterium consists of DNA and cytoplasm
  surrounded by a cell membrane and a cell wall.
• Most bacteria have DNA that is one coiled,
  circular chromosome.
• Many bacteria also have one or more small
  circular pieces of DNA called plasmids that are
  separate from their other DNA.

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Lesson 1
Characteristics of Bacteria (cont.)

• Bacteria are much smaller than plant or animal
  cells.
• They have one of three basic shapes
• round or sphere (cocci)
• Rod (bacilli)
• Spiral (spirilli)

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10-1 Bacteria

• single-cell organisms with no nucleus
  (prokaryote.)
• 3 common shapes

Cocci- round
Spirilla- spiral shaped
Bacilli- rod shaped
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Bacteria clustering
diplo - pairing of cells strepto - chains
staphylo - clusters
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Lesson 1
Characteristics of Bacteria (cont.)

• Bacteria live in many different places and obtain
  food in various ways.
• Some bacteria take in nutrients from dead
  organisms or living hosts.
• Some bacteria make their own food using energy
  from light or chemical reactions.

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Lesson 1
Characteristics of Bacteria (cont.)

• Bacteria that can live where there is no oxygen
  are called anaerobic.
• Bacteria that need oxygen are called aerobic.

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Lesson 1
Characteristics of Bacteria (cont.)

• Some bacteria are able to find their resources by
  moving around with special whiplike structures
  called flagella.

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Flagella

• Help bacteria move in watery environments

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Binary Fission

• Bacteria reproduce asexually by fission- cell
  division that forms two genetically identical
  cells.

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Lesson 1

• Genetic variation can be increased by a process
  called conjugation, in which two bacteria of the
  same species attach to each other and combine
  their genetic material.

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Lesson 1
Endospores

• An endospore forms when a bacterium builds a
  thick internal wall around its chromosome and
  part of the cytoplasm.
• An endospore can protect a bacterium from intense
  heat, cold, or drought.
• Endospores can remain dormant for months or even
  centuries.

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Lesson 1
Endospore Formation
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Lesson 1
Archaea

• Prokaryotes called archaea are similar to
  bacteria, but the ribosomes of archaea more
  closely resemble the ribosomes of eukaryotes than
  those of bacteria.
• Archaea contain molecules in their plasma
  membranes that are not found in any other known
  organisms and often live in extreme environments
  such as hot springs and salt lakes.

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Kingdom Archaebacteria

• Live where no other living things are found
• Ex hot springs, beneath ice in Antarctica,
  volcanic vents
• 3 main types
• Salt lovers
• Heat lovers
• Methane makers

The yellow coloring in the water at the Midway
Geyser Basin in Yellowstone National Park is
caused by archaebacteria. Archaebacteria are
known to surviveat extremely high temperatures
like those produced from a geyser.