Download Virus , Bacteria , and Fungi

Virus, Bacteria,
Protists, and Fungi
Chapters 19-21
What a virus is… and
isn’t.

A virus is not a cell.
– No nucleus, cell membrane, ribosomes,
mitochondria, chloroplasts, etc.

A virus is very small.
– 3000 poloviruses could be contained in the
period at the end of this sentence.

A virus is not complex.
– Genes: Humans (100,000), Bacteria (1000), a
Virus… just 5!
Viral Structure

Nucleic Acid
– DNA or RNA, but not both.

Protein Coat (capsid)
– Protects the nucleic acid from its environment.

Envelope
– Only found in viruses that infect animals.
– Spike-like projections that recognize animal cells
and bind to the cell surface.
Section 19-2
Tobacco Mosaic
Virus
T4 Bacteriophage
Head
DNA
Influenza
Virus
RNA
Capsid
proteins
Capsid
RNA
Tail
sheath
Tail
fiber
Surface
proteins
Membrane
envelope
Viral Replication




Viruses don’t reproduce, they replicate.
Viruses cannot replicate on their own.
Host cells.
Lytic Cycle.
– When the virus enters the cell it immediately begins to
replicate, rapidly killing the cell.

Lysogenic Cycle.
– Viral DNA is inserted into the host cell’s DNA. This DNA,
called a PROPHAGE, may be reproduced several times
and eventually reactivates.
Lytic and Lysogenic Infections
Are viruses alive?

Properties of Life:
– Highly organized. Yes or no?
– Use energy. Yes or no?
– Grow and develop. Yes or no?
– Reproduce. Yes or no?
– Respond and adapt. Yes or no?

Most scientists would say… NO.
Figure 19-11 Viruses and Cells
Section 19-2
What are vaccinations?

The process of injecting a person with
a harmless (weakened or dead) form
of a virus to stimulate the immune
system to produce cells and proteins
that will destroy that type of virus.
Bacterial Structure

Figure 14.10
– Flagella
– Cell Membrane
– Ribosome
– Pili
– Chromosome
– Cell Wall
The Structure of a Eubacterium
Section 19-1
Ribosome
Peptidoglycan
Cell
Cell
wall membrane
Flagellum
DNA
Pili
Survival/Reproduction

Binary Fission: the process by which bacteria

replicate chromosomes and the cell divides.
Power of doubling (1 penny doubled 20 times)
1048576 cents or $10,485.76
Average bacteria doubles every 15-20 minutes

Endospores


– Thick-walled reproductive structures that can
resist heat, drought, and radiation,
sometimes living centuries before breaking
open.
Classifying Bacteria

Archaebacteria (“ancient”)
– Methanogens: produce methane.
– Thermophiles: heated conditions
– Halophiles: salty conditions

Eubacteria
– “True Bacteria” – live in much less harsh
environments than archebacteria. Many types and
ways to classify.
Classifying Bacteria, cont.

Shapes
– Spheres (cocci), rods (bacilli), spirals
(spirilla), chains (streptococci), clusters
(staphylococci).

Cell Wall Composition
– Gram-positive, Gram-negative.


Nutrition (autotroph, heterotroph)
Respiration (aerobes, anaerobes)
The Roles of Bacteria

Decomposers.
– Breakdown dead material.
– Convert (fix) nitrogen into usable forms for
plants.

Symbiosis.
– “You scratch my back – I’ll scratch yours.”

Bacteria can be harmful.
– Slides of deadly bacteria.
Common Diseases Caused by Bacteria
Section 19-3
Disease
Pathogen
Prevention
Tooth decay
Streptococcus mutans
Regular dental hygiene
Lyme disease
Borrelia burgdorferi
Protection from tick bites
Tetanus
Clostridium tetani
Current tetanus vaccination
Tuberculosis
Mycobacterium tuberculosis
Vaccination
Salmonella food poisoning
Salmonella enteritidis
Proper food-handling practices
Pneumonia
Streptococcus pneumoniae
Maintaining good health
Cholera
Vibrio cholerae
Clean water supplies
Section 19-3
Common Diseases Caused by Viruses
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
DNA
Cancer
Retrovirus
RNA
Cancer, AIDS
Adenoviruses
DNA
Respiratory infections
Herpesviruses
DNA
Chickenpox
Poxviruses
DNA
Smallpox
Protists



Common characteristic: EUKARYOTES
Very diverse (20 new kingdoms?)
Three general categories:
– Animal-Like Protists (p. 355-357)
– Plantlike Protists (p. 358-361)
– Funguslike Protists (p. 362-364)
Concept Map
Section 20-1
Protists
are classified by
Animallike
Plantlike
which
which
which
Take in food from
the environment
Produce food by
photosynthesis
Obtain food by
external digestion
Funguslike
which include
Decomposers
Parasites
Animallike Protists: Protozoans
Section 20-2
A.
Zooflagellates
B.
Sarcodines
C.
Ciliates
1. Internal Anatomy
2. Conjugation
D.
Sporozoans
Figure 20-4 An Amoeba
Section 20-2
Contractile vacuole
Pseudopods
Nucleus
Food vacuole
Figure 20-5 A Ciliate
Section 20-2
Trichocysts
Lysosomes
Oral groove
Gullet
Anal pore
Contractile vacuole
Micronucleus
Macronucleus
Food vacuoles
Cilia
Section Outline
Plantlike Protists: Unicellular Algae
A. Chlorophyll and Accessory Pigments
B. Euglenophytes
C. Chrysophytes
D. Diatoms
E. Dinoflagellates
Section 20-3
Euglena
Section 20-3
Chloroplast
Carbohydrate
storage bodies
Gullet
Pellicle
Flagella
Eyespot
Nucleus
Contractile
vacuole
Plantlike Protists: Red, Brown, and
Green Algae
A.
Red Algae
B.
Brown Algae
C.
Green Algae
1. Unicellular Green Algae
2. Colonial Green Algae
3. Multicellular Green Algae
Section Outline
Funguslike Protists
A. Slime Molds
1. Cellular Slime Molds
2. Acellular Slime Molds
B. Water Molds
Section 20-5
Figure 20-23 The Life Cycle of an Slime Mold
Section 20-5
MEIOSIS
FERTILIZATION
Mature
sporangium
Spores
Zygote
Germinating
spore
Young
sporangium
Mature
plasmodium
Feeding
plasmodium
Haploid (N)
Diploid (2N)
Fungi

3 Common characteristics:
– Cell wall are chitin. Same covering as
insects.
– Made of individual filaments, called
hyphae. Tubes full of cytoplasm and
nuclei.
– Masses of hyphae combine to form the
mycelium. This is the body of the fungus.
Hyphae Structure
Section 21-1
Nuclei
Cell wall
Cytoplasm
Cross wall
Cytoplasm
Hyphae With Cross Walls
Nuclei
Cell wall
Hyphae Without Cross Walls
The Life Cycle of a Basidiomycete
Section 21-2
Fruiting body (N + N)
Gills lined
with basidia
Cap
Button
Gills
Stalk
Base
Basidia
(N + N)
Secondary
mycelium (N + N)
FERTILIZATION
HYPHAE FUSE
Primary mycelium (N)
Zygote (2N)
- Mating type (N)
Haploid
+ Mating type (N)
MEIOSIS
Diploid
Basidiospores (N)
How does a fungus eat?


Heterotrophs
Diffusion: most fungi absorb small organic
nutrients from their environment.

Saprophytic: they absorb nutrients from
dead or decaying organic matter.