Chapter 2, Section 2: Bacteria
The Bacterial Cell
I.
Cell structures
a. Bacteria discovered by Anton van Leeuwenhoek in the late
1600s
b. Unicellular
c. Prokaryotes (genetic material not contained in a nucleus)
d. Flagella – help bacteria cells to move by spinning in place like a
propeller
II.
Cell Shapes and Sizes
a. Three different shapes:
i. Spherical
ii. Rod-like
iii. Spiral
b. Vary in size and are measured in micrometers (1 micrometer =
one millionth of a meter)
Obtaining Food and Energy
III.
Obtaining Food
a. Must have a food source and a way of breaking down the food
to release its energy
b. Can be autotrophs (use sun’s energy as plants do or use energy
from chemicals in the environment)
c. Can be heterotrophs (gain energy from the organisms they
consume)
IV.
Respiration
a. Need a constant supply of energy to carry out life processes
b. Respiration is the process of breaking down food to release its
energy
c. Most bacteria need oxygen to break down their food, but some
will die if oxygen is present
Reproduction: bacteria reproduce best under proper conditions: plenty
of food, proper temperatures, and other stable conditions
V.
Asexual Reproduction: involves only one parent to produce
offspring that are identical to the parent
a. Binary fission: one bacteria cell divides to form two identical
cells
i. Each new cell receives a complete copy of the parent
cell’s genetic material, some cytoplasm, and ribosomes
VI.
Sexual Reproduction: involves two parents combining their genetic
material to form a new organism that is different from both
parents
a. Conjugation: one bacterium transfers genetic material to
another bacterium through a threadlike bridge
VII.
Endospore formation
a. In harsh conditions some bacteria form endospores
b. Endospores are small, rounded, thick-walled resting cells that
form inside a bacterial cell’s genetic material and cytoplasm
i. Protect genetic material and cytoplasm from freezing,
heating, and drying conditions