Download Section 2-Bacteria

Section 2-Bacteria
The Bacterial Cell

Anton van Leeuwenhook makes an
accidental appearance once again with the
discovery of bacteria in the 1600s-by
looking at the scrapings of his teeth, he
discovered “worm-like organisms”
Cell Structures
Bacteria are PROKARYOKES because
they lack structures such as the
mitochondria and golgi bodies.
 The genetic material in their cells is NOT
contained in the nucleus. Bacteria lack a
nucleus.
 The cytoplasm contains the ribosomes
and genetic material.

How Do Bacteria Move?
Bacteria may also have flagellum (whip-like
structures that help bacteria move)
 A Flagellum moves the cell by spinning in
place like a propeller.

Cell Shapes and Sizes
Bacteria vary in size.
 Bacteria have three common shapes:
spherical, rod-like or spiral.
 The chemical makeup of the cell wall
determines the shape of the bacterial cell.
 The shape of the bacteria helps scientist
identify the type of bacteria.

Obtaining Food and Energy
Bacteria must have a source of food and a
way of breaking down food to release its
energy.
 Bacteria can either be autotrophic or
heterotrophic.
 Autotrophic bacteria use energy from the
sun or can use chemicals from their
environment to maker their food.
 Heterotrophic bacteria consume other
organisms or the food other organisms
make.

Respiration
This is the process of breaking down food
for a source of energy.
 Some bacteria need oxygen in order to
break down their food.

Reproduction
When bacteria have plenty of food, the right
temperature and other suitable conditions, they
thrive and reproduce. (Bacteria can reproduce in
as quickly as 20 minutes!)
 Bacteria reproduce by a process called binary
fission.
 Binary fission is a form of a-sexual reproduction
in which one cell divides to form two identical
cells. The cell duplicates its genetic material and
then divides into two separate cells. Each new
copy receives a copy of the parents genetic
material, ribosomes and cytoplasm.

Continued
Asexual reproduction is a reproductive
process that only involves one parent and
produces offspring identical to the parent.
 (Imagine your mom only having you, and
when you were born you were identical
to your mother!)

Sexual Reproduction
Some bacteria at times undergo sexual
reproduction.
 Sexual reproduction requires two parents to
combine genetic material to produce a new
organism that differs from the parent cells.


Another form of sexual reproduction is
conjugation. Conjugation is the process of offering
some genetic material to another bacterium
through a thread-like bridge. After the transfer,
the cells separate.
Endospore Formation
During times of harsh conditions, bacteria
form endospores to survive.
 Endospores are small, rounded, thickwalled cell that contains some of the
bacteria’s genetic material and cytoplasm.
 Because endospores can resist severe
freezing, heating and drying, they can
survive for many years.

Bacteria in Nature
Bacteria are involved in oxygen and food
production, environmental recycling and
cleanup and aid in health maintenance and
medicine production.
 Scientist credit autotrophic bacteria with
providing the first sources of oxygen in
the air.

Bacteria and Food Production

During pasteurization, the food is heated
to a temperature that is high enough to
kill most harmful bacteria without
changing the taste of the food.

Examples of foods affected by bacteria:
cheese, pickled vegetables, dried meats,
sourdough bread
Bacteria in the Environment
Heterotrophic bacteria contribute to the
decomposition of things in the
environment.
 Decomposers are organisms that break
down large organisms into small
chemicals. They are known as nature’s
recyclers.
 Some bacteria help to clean Earth’s land
and water. Ex: the bacteria that “eats” oil
from the ocean.

Health and Medicine
Bacteria in your body actually keeps you
healthy! Ex: Intestinal bacteria keeps your
body regular.
 Some bacteria make vitamins your body
needs.
 Bacteria is also used to make medicines
and can be manipulated to make human
insulin.
