Download Viruses and Bacteria

 Maintain
homeostasis
 Reproduction
 Cellular organization
 Metabolism (use energy)
 Contain genetic information
Viruses are particles of nucleic acid,
protein, and in some cases, lipids.
•
•Differ
widely on shape and size.
•Viruses
are not considered to be living
because………
• Use the machinery of other cells
to produce more viruses.

A typical virus is composed of a core of
DNA or RNA surrounded by a protein
coat.
 Remind me of the Hershey-Chase
experiment….

A viruses protein coat is called its capsid.
› Proteins on the capsid bind to receptors on
the surface of a cell; most viruses are highly
specific.
 Plant virus infect plant cells.
 Animal viruses infect only certain related
species.
 Bacterial viruses only infect certain types of
bacteria.

What is it?
› A virus that infects bacteria.

Lytic Infection- a virus enters a cell,
makes copies of itself, and causes the
cell to burst.

Lysogenic infection- virus integrates its
DNA into the DNA of the host cell, and
the viral genetic information replicates
along with the host cell’s DNA.
› The viral DNA that’s embedded in the host’s
DNA is called a prophage.
 Does not lyse the cell right away; remains
inactive for a period of time.
 Eventually the prophage will remove itself from
the host cell DNA and will begin synthesizing
new virus particles.

Some viruses contain RNA-> these are
known as retroviruses.
› When they infect a cell they produce a DNA
copy of their RNA.
 Why are they called retroviruses?
 HIV is an example of a retrovirus.

The best way to protect against most
viral diseases lies in prevention, often by
the use of vaccines.
› Regarding vaccines…….

What is a prokaryote?
› Single-celled organisms that lack a nucleus.

Bacteria have been divided into two
groups, what are they?
› Eubacteria and archaebacteria.
 Which is larger?
 Eubacteria

Live almost everywhere, including the
human intestines.
› Escherichia coli (E. coli)

The cell walls of eubacteria contain this:
› Peptidoglycan, a carbohydrate.

Archaebacteria lack the peptidoglycan
of eubacteria, and live in extreme
environments.
› Hot springs
› Utah’s Great Salt Lake
› Includes methanogens
 Where are some methanogens found? What
do they produce?

Shape:
› Bacilli, cocci, and
spirilla.

Cell Walls:
› Gram +/Gram –
› Stains the
peptidoglycan in the
cell walls.

Movement:
› Flagella, glide, some are
stationary.
Proteus vulgaris