Chapter 10

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