2. Bacteria Viruses
Ribosoms Present Absent
Living
attributes
Living Organism Opinions differ on
whether viruses
are a form of life
or organic
structures that
interact with living
organisms.
Number of
cells
Unicellular; one cell No cells; not living
Structures DNA and RNA floating freely in
cytoplasm. Has cell wall and cell
membrane.
DNA or RNA
enclosed inside a
coat of protein.
Cell Wall Peptidoglycan/Lipopolysaccharide No cell
wall.Protein coat
present instead.
Treatment Antibiotics Vaccines prevent
the spread and
antiviral
medications help
to slow
reproduction but
can not stop it
completely.
Enzyms Yes Yes, in some
Nucleus No No
Virulence Yes Yes
Infection Localized Systematis
Benefits Some bacteria are beneficial (e.g.
certain bacteria are required in
the gut)
Viruses are not
beneficial.
However, a
particular virus
may be able to
destroy brain
tumors (see
references).
Viruses can be
useful in genetic
engineering.
Reproduction Fission- a form of asexual
reproduction
Invades a host cell
and takes over the
cell causing it to
make copies of the
viral. destroys the
host cell releasing
new viruses.
Size
3. 4.
5.
6.
7.
8.
9. Person-to-person
Touch
A cold can be caught by shaking the hand of a person who has a cold and who has just used their
hand to wipe their dripping nose. The mucus from the nose will be teeming with cold virus
particles such as the rhinovirus, which causes one third of colds in adults. Once the cold virus
particles are on the hands of the second person they are contaminated and the virus can be
transferred into their nose by their fingers.
Contaminated blood or other bodily fluids
Hepatitis B and HIV can be spread through sexual intercourse or sharing used syringe needles
contaminated with infected blood.
Saliva
A cold or the flu can be caught from the saliva of an infected person when you kiss them.
Air
Measles, mumps and tuberculosis can be spread by coughing or sneezing. A cough or a sneeze
can release millions of microbes into the air in droplets of mucus or saliva which can then infect
somebody else if they breathe in the infected particles.
