1. Pathogenic Bacteria and Viruses
The bad guys

2. VIRUSES VARY IN STRUCTURE
due to the different proteins that
make up the viral coat
HOWEVER the essential design is
the same: A core of nucleic acid
wrapped in a protein coat.
A VIRUS LACKS CELL
‘MACHINERY’ therefore a
virus is not alive

3. Ex: BACTERIOPHAGE –attacks bacteria

4. BACTERIOPHAGES
attack bacteria

5. Ex: HIV; INFLUENZA
These have an additional
layer - the envelope -
surrounding the coat

6. REPRODUCTION: The LYTIC CYCLE:
Virus enters host, destroying host DNA.
Replicates self like mad, until cell bursts
releasing 100’s of new viruses, ready to
invade more host cells.

7. 1. Virus enters cell; it’s DNA/RNA is incorporated into host DNA.
REPRODUCTION :
The LYSOGENIC CYCLE:
1. Virus enters cell; it’s
DNA/RNA is incorporated
into host DNA.
2. Host cells lives, producing
more viral DNA/RNA as it
divides.
3. Virus lives on in host for
life with periodic outbreaks
The original recombinant DNA!

8. A VIRUS CAN MOVE
from the lysogenic
to the lytic cycle
i.e. herpes viruses
have it for life, but only the occasional outbreak

9. BACTERIA ARE
PROKARYOTES:
DNA localized (but not
bound by a membrane)
in the cytoplasm
Other Structures:
PLASMIDS of DNA
RIBOSOMES for
protein production
CELL MEMBRANE
and a CELL WALL
FLAGELLA for motion

10. TYPICAL BACTERIA SHAPES
cocci, bacilli, spirilla

11. Bacteria form ENDOSPORES
when conditions are not
optimal for survival.
Endospores can lie dormant
for 1000’s of years!

12. BINARY FISSION – asexual reproduction

13. CONJUGATION – sexual
reproduction; plasmid DNA
moves between two organisms
via PILI on cell surface