Chapter 7!Viruses, Bacteria, Protists, &
Fungi!p. 208
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Vocabulary• virus!• bacteria!• protist!• fungi!• vaccine!• pasteurization!• protozoan!!
• parasite!• host!• pseudopod!• flagellum!• cilia!• decomposer
Virus - a non-living particle that invades
and multiples inside a living cell
Viruses
Is a virus alive? !!
Is it an organism?
A Flu Virus
• non-living!• multiply differently
than organisms!• multiplies inside host!• act like parasites
Characteristics of Viruses
Host - organism on which a virus lives!
!
Parasite - organism that lives on host
and causes it harm
• smaller than cells!• vary in size and shape: rods,
bricks, threads, etc.!• protein coat: protects virus!• inner core made of genetic
material: contains instructions for making new viruses!
• envelope: outer membrane on some viruses
Structure of Viruses
Rod-shaped viruses
Structure of VirusesEach virus contains unique surface proteins. The shape of the surface proteins allows to the virus to attach to certain cells in the host. This “lock and key” action is specific to each virus.
1. Virus attaches to cell!2. Virus enters cell!3. Virus’s genetic material takes
over cell functions!4. Instructs cell to produce
virus’s surface proteins and genetic material!
5. Proteins and genetic material assemble into new viruses
How Viruses Multiply
Active Viruses - !go into action immediately!
Ex. Flu,Colds
A !Common
Cold !Virus
Hidden Viruses - !Genetic material becomes part of cell’s genetic material, but does not appear to affect cell
functions; may stay inactive for years until conditions are just
right to become active!!
Ex. Cold sores!Shingles
Viruses can affect people, plants, and
animals.
A Plant Virus
There are no cures for viral diseases.
How to Treat Viral Diseases!1. Rest!2. Drink fluids!3. Eat wellWhy do you think
each of these helps treat the virus?
Vaccine - substance introduced into the
body to destroy specific disease causing viruses
Preventing Viruses
M-M-R Vaccine
What Diseases Does M - M - R help prevent?
1. Flu!2. Polio!3. Chicken pox!4. Measles
Vaccines
What are these diseases? !Use iPads to learn about them.
Bacteria - !single celled
organisms without a nucleus
Bacteria
Microscopic view of bacteria
Are bacteria alive? !
How do you know?
Hint: Characteristics of
Life…!Do you remember?
Are Bacteria…!1. Made of Cells?!2. Composed of Chemicals?!
!
Do Bacteria…!4. Need Food & Energy?!5. Reproduce?!6. Grow & and Develop?!7. Respond to their Environment?!8. Release Waste?
• Autotrophs or heterotrophs!Who remembers? !Autotrophs vs. heterotroph…!• Conduct respiration and
break down food for energy
Bacteria Need !Food and Energy
Structure of Bacteria
• No nucleus!• Vary in size: largest
about as big as a period at the end of a sentence; some only one millionth of a meter
Bacteria magnified on the
head of a pin
• Shapes: spheres, rods, spirals!
• May have a flagellum
Structure of Bacteria
Flagellum - !whip-like structure that
helps a cell move
Structure of Bacteria
Role of Bacteria1. Produce Oxygen!2. Produce Foods!3. Decomposers!4. Environmental Recycling &
Cleanup!5. Health & Medicine
Not all Bacteria are Bad!
As Autotrophic Bacteria use the sun’s
energy to produce their food, they release
oxygen into the air
Autotrophic bacteria releases oxygen
Cyanobacteria in water is
autotrophic
As Bacteria grow in certain substances they produce foods such as…!• cheese!• pickles!• yogurt!• sour cream
Some bacteria cause food to spoil when they break
down the foods’s chemicals. Spoiled food
usually smells & tastes foul and can make you sick. !To prevent this you can
refrigerate or heat the food.
Pasteurization - heating food to kill bacteria
Louis Pasteur!French scientist!
(1822 - 1895)!Also developed
vaccines for anthrax and
rabies
What do you probably drink every day that is
pasteurized?
And the Answer is…
Hetereotrophic Bacteria in the soil are decomposers -
organisms that break down dead organisms !
They are nature’s “recyclers”.!!
Some bacteria can clean oil or chemicals and help with
environmental cleanup.
Oil-eating bacteria can help clean oil
spills.
Did you know many bacteria living in your body keep you
healthy?!!
• Bacteria in intestines help digest food!
• Bacteria compete for space with harmful bacteria!
• Bacteria is used to produce human insulin which helps those with diabetes
Protists
Protist - !one celled organism
with a nucleus
Protists
1. Animal - like!2. Plant -like
Protozoan - animal-like protist!
• With pseudopods!• With cilia!• With flagella!• Parasites
Animal-Like Protists
Pseudopod - !temporary bulge or
“false foot”, for movement!
!
Amoeba with Pseudopods
Amoeba Feeding
Cilia - !tiny hairs used for
movement
Paramecium with Cilia
Flagellum - !whip-like structure used for movement
Euglena with Flagellum
Who remembers -What is a parasite?
Flea
Tick
Plant-Like Protists
• Diatoms!• Dinoflagellates!• Euglenoids!• Algae
When diatoms die, they slowly sink to the seabed. The buildup of trillions of these shells forms a
crumbly white sediment which is used in manufacturing pool filters and abrasives, !
including toothpaste.
Fungus-Like Protists• Slime Molds!• Water Molds!• Mildews
Slime Mold
Bread Mold
Mildew on Leaf
Fungi - !multi celled organisms
Characteristics of Fungi!• Eukaryotes!• Cell Walls!• Heterotrophs!• Feed by absorbing
Food!• Use spores to
reproduce
Mushrooms
Fungi on Tree
Role of Fungi!• Food!• Decomposers!• Fight diseases!• Cause some plant
diseases!• Help some plant roots!• Lichens
Alexander Fleming!Scotland!
1881 - 1955
Nobel Prize 1945
Lichen = fungus + algae or autotrophic bacteria living in mutualism;!
Pioneer species
Lichens on tree!!
Mutualism!!
Fungus gets food produced by the algae or bacteria. Algae or bacteria get shelter, water,
and minerals from the fungus.