Download Lesson 1 | What are bacteria

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Date
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LESSON 7-1 (pages 231-235)
Lesson Outline
What are bacteria?
A. Characteristics of Bacteria
 __Bacteria_____ are microscopic prokaryotes.
 A typical bacterium consists of DNA and cytoplasm
by a cell membrane and a cell wall.

Bacterial DNA occurs in one coiled, circular
surrounded
_chromosome____.
 Bacteria are much ____smaller______ than plant or animal cells.
 Bacteria generally have one of three basic shapes—sphere (cocci), rod (bacilli),
or __Spiral___ (spirilli).
 Some bacteria take in nutrients from dead organisms or _living hosts.
 Other bacteria make their food using energy from ___light___ or
chemical reactions.
 __Anaerobic_____ bacteria can survive without oxygen.
 __Aerobic ___bacteria need oxygen, as humans do.
 Many bacteria have long whip-like structures called ___flagella___ that
they use for movement.

Bacteria reproduce asexually by ___fission___. This type of cell
division forms two genetically ___identical___ cells.

During __conjugation_____, two bacteria of the same species attach to each other and combine
their genetic material.
B. Endospores
 A(n) __endospore__forms when a bacterium builds a thick inner wall
around its chromosome and part of the cytoplasm.
 An endospore can protect a bacterium from intense heat, cold, or__drought__. It can remain
__dormant__for months or even centuries.
C. Archaea
 Like a bacterium, a(n) __Archaea___has a cell wall but no nucleus
or membrane-bound organelles.
 The ribosomes of Archaea more closely resemble the ribosomes of
___eukaryotes__ than those of bacteria.

Archaea often live in ___extreme__ environments, such as hot springs
and salt lakes.