Honors Biology Module 4 Kingdom Fungi Part 2

Honors Biology Module 4 Kingdom Fungi Part 2 October 8, 2015

Class Challenge Bread Molds

Questions from reading and homework

Quiz

Yeasts Yeast is probably the most well-known member of phylum Ascomycota. 1. Most yeasts are saprophytic; 2. They reproduce sexually, producing ascospores; 3. They have a form of asexual reproduction called budding.

When a yeast buds, the nucleus of the cell reproduces inside a single cell. A section of the cell wall and plasma membrane then swell to form a pouch, into which the nucleus and some cytoplasm flow. This pouch with its nucleus is called a bud. The bud continues to grow until it is about the same size as the parent, and then the two cells separate. Budding is distinct from the asexual reproduction that we learned with bacteria, because the daughter cell remains attached to the parent cell as it grows.

Yeasts are typically egg-shaped cells that are only somewhat larger than bacteria. Besides a nucleus, about the only organelle in a yeast cell is a vacuole that stores food substances and certain chemicals that the yeast needs. Certain species of yeast store substances useful to humans in these vacuoles. Some yeasts store vitamins in their vacuoles, so people eat these yeasts in a ground-up form to obtain these vitamins. (brewer’s yeast)

Baker’s Yeast Is a Saccharomyces and is purchased at the grocery store. When mixed with water, these spores mature into yeast cells that can carry on a process called fermentation. Fermentation: The anaerobic breakdown of sugars into smaller molecules

Fermentation Is responsible for making bread dough rise. The yeast mixed with the bread dough feed the sugars in the bread, breaking them down into alcohol and carbon dioxide. Since carbon dioxide is in gas, it pushed its way out of the dough, causing the dough to rise. When the dough is put into the oven, the yeasts are killed and the alcohol evaporates.

The Smell of Bread Baking…. Is a mixture of two things: 1. Alcohol 2. Ozone

Other uses for Yeasts Manufacturing of Alcoholic beverages such as beer and wine. Since one of the products of fermentation is alcohol, yeasts re used to put the alcohol into the alcoholic beverages. Yeast feed on the hops (a plant) and barley to perform the fermentation process in the manufacture of beer.

In the manufacture of wine, yeast feed off the sugars in the grapes (or other fruits) that are used. Note: yeast cannot survive in high concentrations of alcohol, so as the fermentation process continues (greater than 4%) and more alcohol is being produces the alcohol ends up killing the yeast.

Distillation Whiskey that have levels of alcohol much greater than 12% are made by taking a drink with 12% alcohol and boiling it. When the mixture of alcohol and water is boiled, the alcohol boils off at a lower temperature than the water. If you collect the vapors produced by the boiling at this lower temperature and condense them, the result is a solution with a higher concentration of alcohol.

Edible Fungi Phylum Ascomycota Morels, (fruiting body looks like a sponge) See figure 4. 7 The ascospores of these fungi are formed within the holes. Wind and rain release the spores, allowing them to travel.

Toxic and Disease Phylum Ascomycota Just because they may look like a sponge does not always mean they are edible. Many are toxic and deadly. Claviceps (ergot of rye) is deadly to humans. This fungus feeds on the rye. If rye bread is made with this fungus, it would be deadly. Historical Examples? See page 112

Dutch Elm Disease and Chestnut Blight These two diseased affect trees and are caused by fungi in phylum Ascomycota. The chestnut trees were an important source of hardwood lumber in the US. This fungus wiped out the American Chestnut tree. Also, many regions have lost Elm trees due to the fungus that causes Dutch Elm disease.

Zygomycota This phylum contains fungi that form zygospores. They are a zygote surrounded by a hard and protective covering. Zygote: forms as a result of sexual reproduction when each parent contributes only half of the DNA necessary to form the offspring. When those two halves are joined together, a full set of DNA is formed and the offspring can begin to development.

Zygomycota Think bread molds…. (Figure 4. 8 Life cycle of bread mold) 1. Asexually reproduce when a stolon lengthens and forms new filaments. New filaments become new mycelium and then a new fungus. 2. Asexual reproduction involves the production of sporangia (from aerial hyphae) that releases spores. 3. Hyphae can fuse together and sexually reproduce to form a zygospore that can then mature into another fungus.

Rhizopus Most common bread mold These fungi have so many reproductive modes at their disposal, their spores are in the air virtually everywhere. If you leave bread out in the open, bread mold spores will eventually and on it and, within a matter of days, the growing mold will be noticeable.

Phylum Chytridiomycota This phylum contains the single-celled fungi called chytrids. These inhabit muddy and aquatic areas, are saprophytic and feed on decaying water plants. There is one parasitic chytrid, which causes the potato wart, which destroyed many potato crops. Chytrids spores have flagella.

Phylum Deuteromycota: The Imperfect Fungi If scientists cannot determine a sexual reproductive phase in its life, it is placed in this phylum until it can be better classified. Penicillium fungus produces the drug penicillin. See page 115

Antibiotic A chemical secreted by a living organism that kills or reduces the reproduction of other organisms. See page 116 “one interesting fact about anitbiotics…. ”

Phylum Myxomycota Slime Molds behave like a fungi when they reproduce, and they behave like a colonial protists when they feed. As a result, there is arguments for placing them in either kingdom. Most of the time you will observe slime molds in their feeding stage when they resemble colonial protoza. They are found on the bark of decaying logs or between they layers of dead leaves used as mulch. See figure 4. 9

Slime Molds Are usually white, red, orange or yellow. They exist in their feeding stage as a mass of living matter called a plasmodium. There is a genus in kingdom Protista that is given the same name. When given to a slime mold implies that they are slimy to the touch.

Slime Molds They are not harmful to plants or animals as they are almost all saprophytic. • Nonsaprophytic slime molds tend to feed on bacteria, although some are parasitic slime molds.

Slime Molds Can move about as a unit in search of food. When the food supply is exhausted, or when unfavorable conditions occur, the slime mold will produce fruiting bodies that are best described as sporophores. (Fig. 4. 9) Some slime molds produce motile spores (spores that can move on their own) while others produce nonmotile spores.

Slime Mold and Water Slime Mold’s main habitat is water. Wherever dead trees, bark, or leaves are kept moist, slime molds are almost certain to grow. To get rid of slime mold, you simply need to dry the area.

Simbiosis in Kingdom Fungi Lichen are produces by a mutualistic relationship between fungus (usually of phylum Ascomycota) and an alga (usually of phylum Chlorophyta). The alga in the relationship produces food for itself and the fungus by means of photosynthesis, while the fungus supports and protects the alga. This is a mutualistic arrangement.

Despite the fact that the algae which make up the known species of lichens can live independently, the fungi that make them up cannot. The alga produces its own food. It can live with or without the fungus. The fungus just makes its survival easier the fungus, cannot live without the food that the alga produces.

Since a fungus of a lichen cannot live without the alga, you might wonder how lichens reproduce. (I know that was keeping you up at night !) Most lichens reproduce by releasing a dustlike substance called soredium. The soredium contains spores of both the alga and the fungus in a protective case. The soredium is like a spore that contains two different spores. Wherever the spore lands, then both the fungus and alga can grow together.

Mycorrhiza This is fungus contained in the plant roots. Remember Mr. Anderson’s youtube lecture describing this.

Experiment 4. 2 Yeast and the Fermention Process OBJECT: To observe the fermentation process and how yeast reproduce through budding.

Experiment 4. 3 Molds OBJECT: To observe various molds and the differences in how they look both macroscopically and microscopically.

Homework Finish OYO Question for Module 4 Finish Study Guide questions for Module 4 Finish Experiments 4. 2 and 4. 3 in lab book Take Module 4 Test Quiz: Mold life cycle and 3 forms of reproduction Notebook check on October 24 through Module 4 Class challenge: