Virus and Bacteria Outline
I. Virus
II. Bacteria
A. microscopic,disease
A. Archae vs. Eu
B. Non-living because
B. Structure
C. Host cell
C. Reproduction
D. Structure (3 parts)
binary fission vs.
E. Lytic vs. lysogenic
Conjugation
F. Examples
D. Bad, examples
G. vaccine
E. Good, antibiotic
Viruses and Bacteria Notes:
Chapter 18
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: draw and label
• 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:
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 form of a
virus to create antibodies
against the virus
2 minute review with partner
1. What are the 3 parts of a virus?
2. Describe the difference between the
lytic and lysogenic cycles.
Bacteria:(formerly Kingdom Monera)
• Archaebacteria:
–
–
–
–
Prokaryotes
Hetero/autotrophic
Live in extreme environments
Have DNA sequences similar
to eukaryotes and are
thought to be their ancestors
• Eubacteria:
– Prokaryotes
– Hetero/autotrophic
– Live everywhere
Structure of a Bacterial Cell:
DNA
• Strong cell wall;
prevents bursting
• DNA in single
circular chromosome
(no nucleus)
• Plasmid: small ring
of DNA
Shapes of Bacteria: add to notes
• Cocci: round shaped
• Bacilli: rod shaped
• Spirilla: spiral shaped
Bacteria replicate (reproduce) by:
• Binary Fission:
Bacteria reproduce
by dividing in half
(asexual)
• Conjugation:
hollow bridge forms
b/t cells and genes
exchanged (sexualcalled “promiscuity”)
The importance of bacteria: (bad)
• Cause disease
(pathogens)
– Ex: strep throat, tetanus,
Lyme disease, tooth decay,
salmonella, tuberculosis
– Fewer deaths from
bacterial infections because
of sanitation and hygiene
(sterilization/pasteurization by heat,
disinfectants)
The importance of bacteria: (good)
• Recycle nutrients
through decomposition
• Nitrogen fixation:
convert nitrogen into a
form plants can use
• Foods: cheese, yogurt
• Medicines: produce
antibiotics to kill bacteria
by blocking growth
/reproduction; insulin
2 minute review with a partner
1. How do bacteria reproduce?
2. Each give one good thing about
bacteria.
3. Each give something bad caused by
bacteria.