Transcript Viruses and Bacteria

The Six Kingdoms:
Chapter 17
Viruses:
 Microscopic
particles that invade cells and
cause disease
 Non-living because they do not grow or
develop or carry out respiration; they can
only reproduce inside living cells (called a
host cell)
Structure of a virus:

Nucleic acid core:
either DNA or RNA
 Capsid: outer
protein coat
 Tail fibers: used to
attach to host cell
Viruses replicate in lytic or lysogenic
cycles: (make a copy)
 Lytic
cycle (active):
 Virus
attaches to host cell
 Injects viral nucleic acid which destroys
host’s DNA
 New viruses made inside the cell
 Host cell pops, releasing virus to infect
other cells
Lytic Cycle:
Lysogenic Cycle:
 Viral
DNA is joined with the host cell’s
DNA (chromosomes) and can be
passed on to daughter cells
 Virus

is present but not active
Explains why some diseases seem to go away
only to reappear later and why some diseases
don’t show up for many years
Lytic and Lysogenic Cycle:
Amoeba sisters …
Examples of Viruses:

HIV, flu, chicken
pox, colds, hepatitis,
measles

Can you guess
which diseases are
caused by lysogenic
cycles and lytic
cycles?

Vaccinations:


Use weakened or dead
form of a virus to create
antibodies against the
virus
How do they work?
6 Kingdoms
 Archaebacteria
 Eubacteria
 Protist
 Fungi
 Plant
 Animal
Bacteria:

Archaebacteria:




Prokaryotes
Hetero/autotrophic
Most ancient kingdom – 3.5
billion years
Live in extreme environments
(deep sea vents/swamps/no
oxygen)
 Eubacteria:
 Prokaryotes
 Hetero/autotrophic
 Live
everywhere
(except extreme
environments)
 Ex: Strep, Tetanus
Structure of a Bacterial Cell:

DNA
Strong cell wall;
prevents bursting
 DNA in single
circular
chromosome
 Plasmid: small ring
of DNA
Bacteria replicate by Binary Fission

Binary Fission:
Bacteria reproduce
by dividing in half
The importance of bacteria:

Cause disease
(pathogens)


Ex: strep throat,
tetanus, Lyme disease
Fewer deaths from
bacterial infections
because of sanitation
and hygiene
The importance of bacteria:

Recycle nutrients
through decomposition
 Foods: cheese, yogurt
 Medicines: produce
antibiotics to kill bacteria

Antibiotic resistance
Yes you need to know this!