Transcript Bacteria and Viruses

Chapter 19
• Complete the top left portion of the graphic
organizer, recording the Characteristics of
Kingdom Archaebacteria and Kingdom
Eubacteria.
• Include the Cell Type, Cellular Organization,
Mode of Nutrition, Cell Wall Component and
Habitat.
Record the answers to the following
questions on the back of your paper:
1. Which of the following characteristics
is NOT true of both Archaebacteria and
Eubacteria?
A. Unicellular
B. All heterotrophic
C. Prokaryotic
D. Have cell walls
2. Which bacterial kingdom lives in
extreme habitats?
A.Archaebacteria
B. Eubacteria
3. What does the root “eu-” mean?
A.Nucleus
B. New
C.True
D.Green
Bacteria are the simplest
and oldest life forms
– fossils show bacteria that are 3.5 billion
years old!
• The oldest fossil evidence on earth is that of
Archaebacteria.
• Archaebacteria are believed to be the
ancestors of both Eubacteria and the other
eukaryotic kingdoms
peptidoglycan
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Cell wall
DNA
Bacteria are categorized according
to their shape and arrangement.
Bacterial Shapes:
• Coccus – spherically shaped
• Ex: Streptococcus
• Bacillus – rod shaped
• Ex: Clostridium botulinum
• Spirillum – spiral shaped
• Ex: Spirillum
Arrangements of shapes:
• single cells or in groups
• Diplo – two
• Ex: Diplococcus (two spheres)
• Strepto – in chains
• Ex: Streptococcus (spheres in a chain)
• Staphylo – in clumps
• Ex: Staphylococcus (a clump of spheres)
On the back of your paper, Identify
these bacterial cells:
4.
5.
6. What would be the name of this
bacterial cell?
A.Diplobacillus
B. Streptococcus
C.Staphylococcus
D.Streptobacillus
On the back of your paper, draw
the following bacterial cells:
7. Diplospirillum
8. Streptobacillus
9. Staphylococcus
Bacteria and You – Good uses
• Foods made with bacteria: yogurt, cheese, sour
cream
• Decomposition
• Bacteria are prevalent in sewage treatment plants,
can be used to clean up oil spills, etc.
• Digestion
Bacteria and You (cont)
• Bacteria can be pathogenic (disease causing) – Not
Good!
• Can damage tissues (ex-Mycobacterium
tuberculosis) or can release toxins (ex: Dental
cavities and Streptococcus)
• Antibiotics - compounds that block the growth and
reproduction of bacteria
• Penicillin – 1st antibiotic
Record your answer on the back
of your paper
10. Which bacterial kingdom is
“disease-causing”?
A. Archaebacteria
B. Eubacteria
Viruses
• Virus = poison in Latin
• Viruses are nonliving
• Don’t fulfill all criteria for life. Viruses do not
meet these characteristics of living things:
• Cannot reproduce on their own - must
infect host cell to reproduce
• lack enzymes for metabolism – must
infect host cell to carry out metabolism
• don’t grow
Virus Shape and Structure
• Viruses have 2 component parts:
1. Nucleic acid core - (DNA or RNA)
2. Capsid (protein coat) surrounds Nucleic acid
core– gives the virus its distinct shape
Examples:
How does a virus infect cells?
1. The virus recognizes a host cell at a
specific receptor site.
2. The virus and host cell interlock like a
puzzle; a lock and key
3. The virus then destroys the cell’s DNA
and takes over metabolic functions
• This specificity explains why each virus
can only invade certain types of cells.
Virus Examples
• HIV – white blood cells
• Polio- nerve cells
• Adenovirus (cold virus)- adenoid tissue
• Hepatitis- liver cells
Type of Viral Infections
1. Lytic Cycle: the virus destroys the host cell by
causing it to lyse (burst)
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Examples of Lytic Viruses:
Adenovirus (cold virus)
Meningitis
Polio
Bacteriophage
protein coat
Bacteriophage DNA
Bacterial
chromosome
Bacteriophage attaches to
bacterium’s cell wall
Bacteriophage enzyme lyses the
bacterium’s cell wall, releasing
new bacteriophage particles that
can attack other cells.
Bacteriophage injects DNA
into bacterium
Bacteriophage proteins
and nucleic acids
assemble into complete
bacteriophage particles
Bacteriophage takes over
bacterium’s metabolism,
causing synthesis of new
bacteriophage proteins and
nucleic acids
Bacteriophage
Bacteriophage DNA
Bacteriophage protein
• Lysogenic Viruses attack the host cell, but do
not immediately kill it
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Viral DNA/RNA (prophage) is inserted into the
host cell’s DNA/RNA
Host cell continues normal functioning, but will
replicate the prophage every time it divides
This cycle may continue for years, but can go
in to the lytic cycle at any time
Examples
• Herpes Simplex I and II
• Human Immunodeficiency Virus (HIV)
Bacterial
chromosome
Bacteriophage DNA
Bacteriophage injects DNA
into bacterium
Bacteriophage DNA (prophage)
can exit the bacterial
chromosome
Lytic
Cycle
Bacteriophage enzyme lyses the
bacterium’s cell wall, releasing new
bacteriophage particles that can
attack other cells
Lysogenic
Cycle
Bacteriophage DNA
(prophage) may replicate with
bacterium for many
generations
Bacteriophage DNA forms
a circle
Prophage
Bacteriophage proteins and nucleic
acids assemble into complete
bacteriophage particles
Bacteriophage DNA inserts
itself into bacterial
chromosome