1. Protists & Fungi Lesson 1 Part 2
Diseases & Biotechnology

2. What is a protist?
Protists are eukaryotes but are not animals, plants, or fungi.
They refer to them as the “odds and ends” of the animal kingdom:
Most of them are unicellular, but some are multi- cellular.
Some are heterotrophs, some are autotrophs and some are, believe it or not, both!
Some protists can move freely and easily but others cannot.
One thing all protists agree on: they all live in moist environments.

3. Three classifications of Protists
Animal-like protists
Plant-like protists
Fungi-like protists

4. Animal-like Protists
They are heterotrophs, able to move around to obtain food.
Most protozoans are unicellular.
There are four types of animal-like protists:
Protozoans with pseudopods: they move and feed by forming temporary bulges of the cells (pseudopods)
Protozoans with cilia: cilia are hair-like projections that move with wave-like motion, kind of like an oar, to sweep food into the organism
Protozoans with flagella: protozoans that use flagella to move
Protozoans that are parasites: protozoans that eat cells and body fluids of their hosts

5. Plant-like Protists
They are autotrophs and use the sunlight to make their own food. We call them algae.
Some are unicellular and others are multicellular.
Some unicellular algae live in colonies (which may have just a few cells or thousands of cells) and most carry out all functions. Some colonies, however, have cells that specialize in certain functions, such as reproduction.
Some types of protists:
Diatoms: have glass-like cell walls
Dinoflagellates: green, orange, and other pigments
Euglenoids: green, found in fresh water
Red algae: seaweeds
Green algae: have green pigments and live in water or on land
Brown algae: seaweeds

6. Fungi-like Protists
They are heterotrophs, have cell walls and use spores to reproduce.
A spore is a tiny cell that is able to grow into a new organism.
Types:
Slime mold: brilliantly colored; live on forest floors and other moist, shady places; feed on bacteria and other microorganisms; live on surfaces of decaying materials; vary in sizes
Water molds & downy mildews: live in water or moist places; looks like fuzz; attacks food crops like potatoes, corn and grapes

7. Examples of Protists Entamoeba histolytica
Causes dysentery, a severe form of amebiasis associated with stomach pain, bloody stools, and fever
Plasmodium, a one-celled parasite transmitted by a mosquito
Causes malaria, which causes flu-like symptoms and intestinal problems
Image above: Plasmodium attacking a red blood cell

8. Fungi Fungi is the plural of fungus (meaning more than one)
Fungi are eukaryotes that have cell walls, are heterotrophs, feed by absorbing their food, and use spores to reproduce.
Fungi need moist, warm places to grow.
For example, they live on moist foods, damp tree barks, lawns coated with dew, damp forest floors, and wet bathroom tiles.
They can be unicellular or multi-cellular.

9. Structure of a fungus
The cells of most fungi are arranged in structures called hyphae, which are branching, thread-like tubes that make up the bodies of multi-cellular fungi.
In some fungi, the hyphae are continuous threads of cytoplasm that contain many nuclei.
Image source:

10. How do fungi eat?
Fungi are heterotrophs, but they do not eat like a typical animal.
Fungi absorb their food in through the hyphae, which often grows around a food source:
The hyphae grow around the food.
Digestive chemicals exit the hyphae to break down the food into smaller substances that can be absorbed.
Some fungi eat dead organisms, others can be parasites feeding on live organisms.
Image source:

11. Reproduction of Fungi Fungi usually reproduce by making spores.
The lightweight spores are surrounded by a protective covering and can be carried easily through air or water to new locations.
Fungi can produce millions of spores, more than will survive.
Conditions must be perfect, such as temperature and moisture, in order for the spores to grow.
There are two ways fungi reproduce:
Asexual
Sexual

12. Asexual reproduction of fungi
This occurs when there is the right amount of water and food.
Cells at the tips of the hyphae divide to form spores.
The spores grow into fungi that are genetically identical to the parent.
Some fungi do not produce spores but rather go through a process called budding.
Budding is when a cell grows away from the body of the parent cell, kind of like a tree budding in the spring to produce a leaf; then the new cell breaks away and lives on its own.

13. Sexual Reproduction of fungi
If growing conditions are unfavorable fungi will reproduce sexually instead.
The hyphae of two different fungi will grow together and exchange genetic material.
Eventually a new structure will grow from the joined hyphae and produce spores, which are genetically different than either parent.

14. Spores & Mold
When mold spores are created through reproduction and released into the air they can cause allergic reactions in humans.
These reactions can range from mild to very serious.
Often times the worst time of the year for this type of allergy is between summer and winter because much of the Earth goes into hibernation, with leaves and flowers dying off and fungi recycling it back into the Earth.

15. Fungi in Nature
Fungi play important roles as decomposers and recyclers on Earth.
Fungi will break down the chemicals in dead organisms.
This process returns nutrients to the soil and cleans up the Earth for free!
Many fungi provide foods for people.
Bread has yeast and yeast is a fungi.
Molds are used to produce cheeses.
People enjoy eating mushrooms, but we cannot eat all mushrooms because some are poisonous.
Some cause diseases but others fight diseases.
The first antibiotic, Penicillin, comes from a mold and helps humans fight off diseases.
Some, though, are parasites and cause diseases like crop diseases, which destroy crops, Athlete’s foot and ringworm.

16. Parasites
A parasite is an organism that feeds on another individual, call a host.
They live either on or inside their host’s body.
Parasites usually specialize for a specific lifestyle.
For example, a tapeworm lives in the host’s intestinal system so the tapeworm doesn’t need a digestive system and doesn’t have one. It absorbs what it needs through the tapeworm’s skin.
Parasites can be viruses, fungi, bacteria or protists.

17. Resources: Epidemic – The World of Infectious Diseases
Welcome Trust Sanger Institute – Press Release on DNA of the tissue destroyer - Genome clues to Amoebic Dysentery
Prentice Hall Science Explorer Grade 8, NC version, 2005
Fungus