Chapter 10
Bacteria and Viruses
Section One: Bacteria and
Archaea
A. Characteristics
of Bacteria and
Archaea
1
. Members of the Domain Bacteria live in soil,
water
, and
other
organisms.
2
. Members of the Domain
Archaea
are found
in
extreme
environments
such as hot
springs
.
3
. There are more bacteria on Earth than all
other
living things combined.
4
. There are 2.5 billion bacteria per one gram of
soil
.
B. Bacteria Shapes
1
.
Bacilli
-
rod shaped bacteria with a large
surface
area
which
helps them take in
nutrients
.
2
.
Cocci
-
spherical shaped bacteria that do
not
dry
out as
quickly
as bacilli.
3
.
Spirilla
-
long and spiral shaped bacteria
that
use
flagella
at
both
ends to move like
a
corkscrew.
C
. Prokaryote versus Eukaryote
1. Prokaryote
-
Single
-
celled organisms that do
not
contain
a
nucleus.
2. Eukaryote
-
Organisms whose cells do contain a
nucleus
.
D
. Reproduction
1.
Binary Fission
: Asexual reproduction where
one
cell divides into two
cells
.
2. See Figure Three on Page 248.
E
.
Endospores
: Thick
-
walled protective spore which
can
survive
extreme
or harsh environments
for long
periods of time.
F. Classification of Bacteria
1. Bacteria
are classified by how they get their
food
.
a. Examples
: Decomposers,
Producers
2.
Cyanobacteria
: Producers which contain
chlorophyll that allows them to undergo
photosynthesis.
G
. Domain
Archaea
1. There
are three main types:
a.
Heat
lovers
-
Bacteria that live in ocean
vents
and hot springs in temperatures
usually
from 60
°
C to 80
°
C but can survive in
temperatures
of more than 250
°
C
.
b.
Salt
lovers
-
Bacteria that live in
environments
that have high levels of salt,
such
as the Dead Sea and the Great Salt
Lake.
c.
Methane
makers
-
Bacteria that give off
methane
gas and live in swamps and
animal
intestines
.
2. These
bacteria prefer little or no oxygen.
3.
Archaea
differ from bacteria:
a. Not
all
archaea
have cell walls.
b. The
cell walls are chemically different.
Section Two: Bacteria’s Role in the
World
A
.
Nitrogen Fixation
-
Process in which nitrogen
-
fixing bacteria take
nitrogen
from the air and
change it into a form that plants can use.
1
. Nitrogen gas makes up about 78% of the
air
, but plants cannot use this nitrogen
directly
.
2
. So, plants rely on nitrogen fixation to
convert
the nitrogen.
B.
Bioremediation
-
Biological treatment of
hazardous wastes by living organisms from
industries, farms, and cities.
C
.
Lactic Acid
-
Producing Bacteria
-
Bacteria
which break down the sugar in milk which is
called
lactose.
1
. In this process, these bacteria change the
lactose
into lactic
acid.
D
.
Antibiotics
-
Medicines that are used to kill
bacteria.
E. In the 1970’s, scientists put genes for human
insulin into
E. coli
bacteria so that the bacteria
would produce human insulin to be used by
diabetics. (
E. coli
stands for
Escherichia coli
)
F
. Genetic Engineering
-
When scientists change
the genes of bacteria or any other living thing
.
1. Scientists have been genetically
engineering bacteria since 1973.
G
. Harmful
Bacteria
1
. Pathogenic Bacteria
-
Bacteria that causes
diseases
.
a
. These diseases can be treated with
antibiotics
.
H
. Bacterial Diseases
Ulcers
Lyme
Disease
Tuberculosis
Typhoid
Fever
Bubonic Plague
Food Poisoning
Dental Cavities
Strep Throat
Leprosy
Section Three: Viruses
A. Viruses are microscopic particles that get
inside a cell and often destroys the cell.
1. They are tiny, smaller than the smallest
bacteria.
2. Five billion virus particles could fit into a
single drop of blood.
B. Viruses contain protein and genetic material
but they cannot eat, grow, break down food, or
use oxygen.
1
. Viruses cannot function on their own and
can
only reproduce once they are inside
a
living
cell that serves as a host
.
a
.
Host
-
A living thing that a virus or
parasite
lives on or in.
C. Classifying Viruses
1. Viruses can be grouped by their shape,
the
type of disease they cause, their life cycle,
or
the kind of genetic material
they
contain
.
a
. Shape Classification
1) Crystals: Example
-
Polio Virus
2) Spheres: Example
-
Influenza and
AIDS
3
) Cylinders: Example
-
Tobacco
Mosaic
Virus
4) Spacecraft: Example
-
Bacteriophage
2. Every virus is made up of genetic
material inside a protein coat.
3
. The genetic material inside viruses is
either DNA or RNA.
a.
RNA
is made up of one strand of
nucleotides.
b.
DNA
is made up of two strands of
nucleotides.
D. Viral Cycles
1.
Lytic Cycle
-
A cycle in which viruses attack
living cells and turn them into virus
factories. (Active and reproductive cycle)
2.
Lysogenic Cycle
-
A cycle in which each new
cell gets a copy of the virus’s genes when
the host cell divides.
a. These genes can stay inactive for a long
time, but when they become active,
they begin the Lytic Cycle.
E. Treating a Virus
1. Antibiotics do not kill viruses.
2.
Antiviral Medications
-
Medicines that stop
viruses from reproducing.
3. Vaccinations can prevent you from getting
certain viruses.
F. Viral Diseases
Colds
Influenza
AIDS(HIV
)
Rabies
Polio
Warts
Chicken Pox
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