Download Bacteria and Viruses

Class Notes 3:
Domain Bacteria, Domain Archae &
Viruses
I. Domain Bacteria
A.
B.
C.
Remember that bacteria are prokaryotes.
This means that they are simple cells.
They do not have a nucleus or organelles!
II. What is the structure of bacteria?
A.
B.
Their DNA can be found in a single circular
chromosome.
They have a cell wall, which prevents the
cell from bursting.
III. How do bacteria reproduce?
A.
B.
There are two ways bacteria reproduce.
Asexually through binary fission and
sexually through conjugation.
IV. Bad Bacteria
A.
B.
Bacteria are responsible for such diseases
as strep throat, tuberculosis, lyme disease,
cavities, and cholera.
Fortunately, we have antibiotics to fight off
bacterial infections.
V. Good Bacteria
A. Nitrogen fixing bacteria live in the roots of
peas and other legumes, adding nitrogen to
the soil.
B. Bacteria recycle dead organisms back into
the earth.
C. Vinegar, yogurt and cheese are all made
with bacteria. Yum!!
D. Good bacteria live in your digestive system.
VI. Domain Archae
A.
B.
C.
Archae are also prokaryotes, and they have
a similar function and appearance to
bacteria.
Molecular evidence shows Archae are not
closely related to bacteria.
Bacteria have a polymer called
peptidoglycan in their cell walls, Archae do
not.
VI. What is a virus?
A.
B.
A virus is considered non-living, so it is not
in a domain.
It invades host cells and uses the
machinery of the invaded cell to make more
viruses.
Influenza-->
VII. What is the structure of a virus?
A.
A typical virus is
made of a DNA or
RNA center,
surrounded by a
protein coat, called a
capsid.
VIII. How viruses work?
A. Lytic Infection
A virus enters the
cell, makes copies
of itself, then causes
the cell to burst
B. Lysogenic Infection
A virus inserts its DNA into the cell. The
host cell copies its own DNA, and also that
of the virus.
C. Viruses and illness
1.
2.
Viruses cannot be destroyed by antibiotics.
A vaccine is a weakened version of a virus
that allows your body to build immunity to
the virus, hopefully preventing you from
becoming ill.
Summary
Why are Bacteria and Archae in separate
domains? What is the difference between
bacteria and viruses?