1. Protists and Fungi
Chapter 17.1, 18.1, & 18.3

2. Kingdom Protista: the most diverse of all eukaryotes
Ch 17.1

3. Protists Protists: eukaryotes that are not animals, plants, or fungi
Most protists are unicellular and free-living (not parasitic)
Protists have the typical eukaryotic cell structure, including internal membranes, a nucleus surrounded by a nuclear envelope, and organelles such as mitochondria and chloroplasts (in some species)

4. Protist Complexity
Being mostly unicellular, protists are considered the simplest form of eukaryotic organism
Most human cells are highly specialized, carrying out only certain tasks
The protist's one cell must consume and process food, respond to stimuli, excrete wastes, and reproduce
Protists can justifiably be considered the most complex of eukaryotic cells, since each cell must carry out all of an organism's life functions.

5. Protist nutrition used for classifying
Scientists group protists by lifestyle: animal-like, fungus-like, and plant-like protists
Protozoans: Animal-like; heterotrophs that ingest (eat) food
Algae: Plant-like; autotrophic making food through photosynthesis

6. Fungi
Ch 18.1 & 18.3

7. Structure & Function of Fungi
Hypha: a thread of cytoplasm; many hyphae together make up the body of a fungus
Mycelium: interwoven mat of hyphae that functions as the feeding structure of a fungus
functions as the feeding structure of a fungus
fungal mycelium can grow as much as a kilometer of hyphae each day as it branches within its food

8. What’s the world’s largest organism?
Scientists have discovered one enormous mycelium in Oregon that measures 5.5 kilometers across and spreads through almost 9 square kilometers of forest (larger than 1,600 football fields)
Scientists also estimate that this fungus is at least 2,400 years old
Qualifies as one of Earth's oldest and largest living organisms

9. Mycelium
The branching mycelium enables the fungus to obtain food by absorptive nutrition
Absorptive nutrition: method by which fungi absorb small organic molecules from their surroundings
First, the fungus digests food outside its mycelium by secreting powerful enzymes into its surroundings
These enzymes break down complex molecules into smaller molecules the mycelium can absorb

10. Fungi’s role Many fungi play an important role as decomposers
Fungi recycle nutrients such as nitrogen and carbon by breaking down organic material
Common food sources for fungi are fallen logs, bodies of dead animals, or the wastes of living organisms
Parasitic fungi absorb nutrients from the cells or body fluids of living hosts
Parasitic fungi cause about 80 percent of all plant diseases

11. Reproduction of Fungi
Fungi reproduce by releasing large numbers of microscopic spores
Spores: haploid single cell with a thick wall that functions in the dispersal stage in fungal reproduction
spread by the wind and can withstand unfavorable conditions for long periods of time
Most fungi produce spores asexually by mitosis at the tips of specialized hyphae
Many fungi also produce spores sexually
Haploid hyphae from different mycelia fuse together and combine their genetic material

12. Fungi have a major impact on other life
Ch 18.3

13. Lichens Lichens: mutualistic pairing of a fungus and an alga
The photosynthetic algae feed the fungus
The fungal mycelium provides a suitable habitat for the algae, helping to absorb and retain water and minerals
Lichen actually consists of millions of tiny algal cells within a mesh of fungal hyphae

14. Lichens
One benefit of symbiosis is that lichens are able to live in environments where neither fungi nor algae could live alone
Lichens are important pioneer organisms on newly cleared rock and soil surfaces, such as burned forests and volcanic flows
In the arctic tundra, caribou graze on lichens at times of the year when other foods are unavailable
As tough as lichens are, however, many do not tolerate air pollution
Their absorption of minerals from rain and moist air makes them particularly sensitive to chemicals such as sulfur dioxide
The death of sensitive lichens in an area can be an early warning of poor air quality.

15. Micorrhizae
Micorrhizae: symbiotic relationships between fungal hyphae and plant roots
The fungi absorb water and essential minerals from the soil and provide these materials to the plant
The fungal mycelium greatly increases the surface area of the root in contact with the soil, which increases the plant's absorption of water and minerals
The sugars produced by the plant nourish the fungi

16. Disease causing fungi
Of the 100,000 known species of fungi about 30 percent are parasites, mostly on or in plants
Dutch elm disease- has eliminated most elm trees in North America
The fungus was accidentally introduced into the United States on logs sent from Europe after World War I
Only about 50 species of fungus are known to be parasitic in humans and other animals
Among these are yeast infections of the lungs, some of which can be fatal
Other fungal parasites produce a skin disease called ringworm, so named because it appears as circular red areas on the skin
Some fungi attack the feet and cause intense itching and sometimes blisters- known as athlete's foot, is highly contagious, but it can be treated with various fungicides

17. Athlete’s Foot

18. Ring Worm

19. Commercial use of fungi
The distinctive flavors of certain kinds of cheeses come from the fungi used to "ripen" them
Yeasts are particularly important in baking, brewing, and winemaking
Used in making of antibiotics
In addition to edible mushrooms, other edible fungi include truffles
In nature, truffles release strong odors that attract mammals and insects that dig up the fungi and disperse their spores

20. Role of fungi in chemical cycling
Fungi and bacteria are the principal decomposers that supply ecosystems with the nutrients essential for plant growth
The air is so loaded with fungal spores that as soon as a leaf falls or an insect dies, it is covered with spores that quickly grow into fungal hyphae
Without decomposers, elements such as carbon and nitrogen would accumulate in organic matter
Plants and the animals they feed would starve because elements taken from the soil would not be returned

21. Questions? Which of the following is a symbiotic relationship?
Penicellium
Bread mold
Yeast
lichen
What do fungi produce that allows them to break down dead organisms?
How do humans use fungi?
To flavor certain foods
As a source of antibiotics
As ingredients in baking and brewing
All of the above

22. Questions? What is an important role of fungi in an ecosystem?
What is the cause of the human disease ring worm?