The Body of a Fungus
Many fungi have slender filaments called hyphae that are continuous, composed of branching tubes, or made up of long chains of cells joined end-to-end and divided by septa. (p. 601)
A mycelium is a mass of connected hyphae that grows into the material in which the fungus is feeding. (p. 601)
Cell walls are formed of polysaccharides and chitin. (p. 601)
 

How Fungi Reproduce
Fungi exhibit both sexual and asexual reproduction. (p. 602)
Sexual reproduction occurs when the haploid hyphae of two individuals fuse. (p. 602)
Most fungi use spores to reproduce. (p. 602)
 

How Fungi Obtain Nutrients
All fungi secrete digestive enzymes into their surroundings and absorb the organic molecules produced via external digestion. (p. 603)
 

Metabolic Pathways
Humans use the metabolic pathways of fungi for commercial products such as cheese, soy sauce, bread, beer, and wine. (p. 603)
Fungi are also used in bioremediation to rid water or soils of environmental contamination. (p. 603)
 

Ecology of Fungi
Fungi are the principal decomposers in the biosphere and are nearly the only organisms capable of breaking down lignin. (p. 604)
Symbioses fall into many categories, including obligate and facultative. (p. 604)
Fungal species are responsible for billions of dollars of agricultural losses annually, and cause many human and animal diseases, including ringworm and athlete's foot. (p. 604)
Lichens are mutualistic associations between fungi and algae or cyanobacteria, while mycorrhizae are specialized mutualistic associations between plant roots and fungi. (p. 604)

30.2 There are four major groups of fungi.
Phylogenetic Relationships
Although the phylogeny of fungi changes rapidly, currently they are divided into four groups (Chytridiomycota, Zygomycota, Basidiomycota and Ascomycota. (p. 605)
Chytridiomycota
The chytrids are aquatic, flagellated fungi that are the closest living relatives to the first fungi. (p. 606)
Zygomycota
The zygomycetes are a very diverse group that includes many of the common bread molds. (p. 607)
Zygomycotes are named after a characteristic feature of their sexual phase, the zygosporangium. (p. 607)
In zygomycetes, asexual reproduction occurs much more frequently than sexual reproduction. (p. 607)
Basidiomycota
Basidiomycetes include mushrooms, toadstools, puffballs, and many plant pathogens, such as smuts and rusts. (p. 608)
Basidiomycetes are named for their characteristic sexual reproductive structure, the basidium. (p. 608)
Ascomycota
The ascomycetes contain about 75% of known fungi, including bread yeasts, common molds, morels and truffles, and many plant pathogens, such as chestnut blight. (p. 609)
Ascomycetes are named for their characteristic reproductive structure, the ascus. (p. 609)
In ascomycetes, asexual reproduction is very common and takes place by conidia produced at the ends of conidiophores. (p. 609)

30.3 Fungi participate in many symbioses.
Lichens
Lichens are symbiotic relationships between a fungus and a photosynthetic partner that colonize even the harshest habitats on the planet. (p. 611)
Lichens vary in their sensitivity to atmospheric pollutants, and some are used as air quality indicators. (p. 611)
Mycorrhizae
Mycorrhizae are mutualistic relationships between plant roots and certain fungi. (p. 612)
The fungi in mycorrhizal associations increase the amount of soil contact and the total absorption area. (p. 612)
Two principal types of mycorrhizae are arbuscular and ectomycorrhizae. (p. 612)
Endophytes
Endophytic fungi live in the intercellular spaces inside living plants. (p. 613)
Mutualistic Animal Symbioses
A range of fungal-animal symbioses has been identified. These include ruminants and the fungi in their gut, and leaf-cutter ants and specific fungal species. (p. 613)
Fungal Parasites and Pathogens
Candida can cause common oral or vaginal infections. (p. 614)
A chytrid can cause chytridiomycosis in amphibians.
Crop losses due to parasitic or pathogenic fungi are extensive throughout the world. (p. 614)
Aflatoxins can cause kidney or nervous system damage. (p. 614)

BIOLOGY 2
TOPIC:Nervous Tissue

The nervous tissue of animals responds to stimuli within and outside of the body. Incoming information is integrated and a response is made. The response is muscle contraction or secretion by a gland. The end result is the maintenance of body functions or homeostasis

Neuron In all neurons, information flows from dendrites to axons. The cell body contains the nucleus. Long extensions may be surrounded by myelin, a fatty material that insulates and increases the rate of electrical transmission.

BIOLOGY 3
TOPIC: DNA:THE GENETIC MATERIAL

RECOMBINANT DNA TECHNOLOGY

Once Homo sapiens starts to understand something, it seems to be human nature to try to manipulate it. Why should genes be exempt from our tinkering? Over evolutionary time, genes change via random (or not so random) mutation and via recombination during meiosis. These processes might seem random to us (though they are often directed by selective forces we cannot easily fathom, since they are many and complex!). Since the 1970's however, humans have been devising techniques by which they can manipulate genes and modify them in (somewhat) predictable and directed ways. Recombinant DNA technology Genetic engineering:Gene cloning are all ways to say essentially the same thing. They mean:isolating desired DNA fragments joining them in new combinations and introducing the newly combined DNA into a living organism.The idea is simple if the practice is not: select the desired gene (or genes) to be inserted into the organism cut two DNA molecules into fragments with special (restriction) enzymes splice the fragments together in the desired combination introduce the new DNA into a living cell for replication.

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