1. Viruses, Bacteria and Protists
Life Science 2017
Viruses, Bacteria and Protists

2. Viruses
Viruses are tiny, nonliving particles that enter and then reproduce inside living cells.
Require a host to obtain energy and reproduce
Act like parasites or organisms that live on or in a host and cause it harm
Almost all destroy their
host cell

3. Viruses vary widely in shape:
Influenza virus
Spherical
Tobacco mosaic virus
Rod shaped
Bacteriophage
Complex, robotlike shapes
“Bacteria eaters”
Much smaller than cells
(cannot be seen with our
Microscopes)

4. How Viruses Multiply Virus enters the host cell
Virus’s genetic material takes over cell’s functions
Cell is instructed to produce virus’s proteins and genetic material (DNA)
New virus is created

5. Virus Structure
Virus surface proteins must match certain host cell membranes
Like a “lock and key”
Reason why the common cold virus infects cells in the nose and throat – the area where this illness is mostly found in humans

6. Usefulness of Viruses
Gene therapy allows scientists to treat certain diseases
Virus acts as “messenger” of reparative DNA
A vaccine is a substance introduced in the body to help produce chemicals that destroy specific viruses.
Often made from weakened or dead viruses
Host cells now recognize the virus as a threat and know how to fight it

7. Amoeba Sisters
Virus Video

8. Bacteria Many bacteria are harmless or even good for you. Examples:
Yogurt
Coat your skin
Inside nose
**There are more organisms inside your mouth than there are people on Earth.

9. Cell Structures First discovered in 1600s by Anton von Leeuwenhoek
Bacteria are prokaryotes whose genetic material is not contained in a nucleus
Contain:
Cell membrane Cell wall
Ribosomes Flagellum
DNA Cytoplasm

11. Food Autotrophic Heterotrophic Some conduct photosynthesis
Some use chemical substances to make food
Heterotrophic
Examples of foods:
Milk
Meat
Decaying plant matter

12. Role of Bacteria in Nature
Oxygen and food production
Autotrophic bacteria help keep atmospheric oxygen levels stable
Health maintenance
Break down food to create new food ie. making cheese and yogurt
Pasteurization removes harmful bacteria through intense heating
Digestive bacteria help keep you healthy
Medicine production
Can be used in the production of insulin
Environmental cleanup and recycling
Decomposers break down chemicals in oil spills

13. Protists
Euglenoid
Amoeba
Slime Mold

14. What Are the Characteristics of Animal-Like Protists?
Protists are eukaryotes that cannot be classified as animals, plants, or fungi.
This kingdom is very diverse
Most are unicellular
Some are multicellular
Some heterotrophs while others are autotrophs
All live in moist locations
3 categories of protists:
Animal-like
protozoans
Plant-like
algae
Fungi-like

15. Animal-like Protists Heterotrophs Most can move to get food
Unicellular
Called protozoans

16. Protozoan Movement and Life
4 Groups:
with Pseudopods
temporary bulges of the cell that form around food (false foot)
with Flagella
Called flagellates who have long whip-like tales
with Cilia
Hair-like projections that beat in waves to move
Parasites
Not classified by movement but instead by how they obtain energy from other organisms

17. Pseudopods
Cytoplasm moves towards side of cell where food is located and rest of the cell follows and surrounds food
Example:
Amoeba

18. Flagellates Some are harmful and some are beneficial
One breaks down food in intestine of termite
Giardia, found in fresh water, causes hiker’s disease

19. Ciliates Cilia help organism move and sweep food into the cell
Example:
Paramecium

20. Parasites Feed on cells and body fluids of their hosts Example:
Plasmodium
(causes malaria
and is transmitted
By mosquitoes)

21. Plant-Like Protists Commonly called algae Autotrophs
Unicellular or multicellular
Use pigments to capture light energy
Green, yellow, red, brown, orange or black

22. Types of Algae Euglenoids Dinoflagellates Diatoms Red algae
Brown algae

23. Fungus-Like Protists Heterotrophs Cell walls Use spores to reproduce
Spores are tiny cells that can grow into a new organism.
Examples:
Slime molds
Water molds
Downy mildews