CHAPTER 20.4: RED, BROWN, AND GREEN ALGAE By: Courtney Pham

Red Algae  Red algae are able to live at great depths due to their efficiency in harvesting light energy.  Contains chlorophyll a and reddish accessory pigments called phycobilins  Phycobilins are especially good at absorbing blue light, enabling red algae to live deeper in the ocean.  Usually color green, purple, or reddish black

Red Algae (continued)  Multicellular  Complex life cycles  Lack flagella and centrioles  Plays important roles in formation of coral reefs and help maintain equilibrium in coral reef system

Brown Algae  Contains chlorophyll a and c, as well as a brown accessory pigment, fucoxanthin  The largest and most complex of the algae  Multicellular  Found in marine areas of the temperate or arctic  Has a holdfast-a structure that attaches the alga to the ground  The body has a stripe, blades(leaf-like structures), and bladders

Green Algae  Share many characteristics with plants, including photosynthetic pigments and cell wall composition  Contain cellulose in cell walls  Scientists believe that green algae share a common ancestor with mosses  Found in fresh and salt water and moist areas on lands  Few are multicellular and have well-developed structures

Types of Green Algae  Chlamydomonas grows in ponds, ditches, and wet soil  Small, egg-shaped, with two flagella and a single large chloroplast  Ulva is commonly found along rocky sea coasts  Contains several specialized cell types  Ulva is two cells thick UnicellularMulticellular

Types of Green Algae ChlamydomonasUlva

Types of Green Algae Colonial Several green algae live in multicellular colonies Filaments- long threadlike colonies Volux colonies are elaborate and consist as few as 500 to 50,000 cells that are arranged to form hollow spheres

Reproduction in Algae  The life cycles of many algae include both a diploid and haploid generation.  alternation of generation- when an algae switches back and forth between haploid and diploid stages in a life cycle  Species also shift back in forth between sexual and asexual forms of reproduction

Asexual Reproduction in Chlamydomonas  Chalmydomonas spends most of its life in haploid stage  If conditions are favorable, the haploid cell reproduces asexually by mitosis, producing cells called zoospores

Sexual Reproduction in Chlamydomonas  If conditions are unfavorable, they reproduce sexually. They undergo mitosis, but instead of releasing zoospores, they release + and - gametes.  The + and – gametes form pairs to join flagella and spin around in the water. They shed their cell walls and fuse to form a diploid zygote.  The diploid zygote then grows a thick protective wall and waits for conditions to become favorable again.  When conditions become favorable, the zygote goes through meiosis to produce four flagellated haploid cells.

Reproduction in Ulva  In the haploid phase, the Ulva produces male and female gametes.  The haploid form of Ulva are known as gametophytes  The male and female gametes fuse and produce a diploid zygote cell that grows into a diploid multicellular Ulva that goes under meiosis to produce reproductive cells called spores.  The diploid form of Ulva are known as sporophytes

Human Uses for Algae  Algae produces much of the Earth’s oxygen through photosynthesis.  Chemicals in algae are used to treat stomach ulcers, high blood pressure, and arthritis.  Pophyra algae is used as a wrapper in sushi rolls.  Ice cream, salad dressing, pudding, and even candy bars contain algae!  Chemicals from algae is also used to make plastics, waxes, deodorants, paints, and more!

Chapter 20.5: Funguslike Protists

Funguslike Protists Compared to Fungi  Funguslike protists are heterotrophic and absorb dead or decaying matter  Funguslike Protists have centrioles and lack chitin in their cell walls Like FungiUnlike Fungi

Slime Molds  Found in areas damp and rich in organic matter  Funguslike protists that play key roles in recycling organic material  Two groups of slime molds are recognized:  Cellular slime molds- cells are separated by cell membranes and the individual cells remain distinct through life cycle  Acellular Slime molds- pass through a stage in which their cells fuse to form large cells with many nuclei

Cellular Slime Molds  Live as free-living cells, much like amoebas  Reproduce rapidly in nutrient-rich soils  When their food supply is exhausted, they go through a reproductive process to produce spores that can survive adverse conditions  In Reproduction, the cell sends chemical signals to attract other cells. The cells aggregate to form a colony. The colony then forms a fruiting body. The spores are scattered from the fruiting body and transforms into single amoeba-like cell.  Fruiting body- slender reproductive structure that makes spores

Acellular Slime Molds  Begin life cycle as amoeba-like cells  When they aggregate, their cells fuse to produce structures with many nuclei called plasmodia  Plasmodium- single structure with many nuclei  Fruiting bodies spring up from the plasmodium and produces haploid spores by meiosis.  The spores germinate into amoeba-like cells that will fuse to produce a diploid zygote.

Water Molds or Oomycetes  Oomycetes thrive on dead or decaying organic matter in water and some are plant parasites on land  Produce thin filaments known as hyphae  Has cell walls made of cellulose and produce motile spores  Oomycetes caused the Potato Famine in

Water Mold Asexual Reproduction  Water molds in asexual reproduction have portions of their hyphae form into zoosprangia.  Zoosporangia- spore cases  During asexual reproduction, the hyphae develops into zoosporangia. The zoosporangia produce flagellated spores that swim away to search for food. After they find food, the spores develop into hyphae. The hyphae then develops into new organisms.

Water Mold Sexual Reproduction  Sexual reproduction takes place in specialized structures formed by the hyphae  Antheridium- structure that produces male nuclei  Oogonium- structure that produces female nuclei  Fertilization, or sexual fusion, occurs within the oogonium, and the spores that develop form into new organisms.

Ecology of Funguslike Protists  They are recyclers of organic material, meaning they help things rot  For example: After organisms die, their tissues are broken down by slime molds, water molds, and other decomposers. As a result, a rich topsoil that provides nutrients for plants is formed.  They can harm living things and are the source of many important plant diseases.

Quiz Time!

What type of algae can live at great depths due to its efficiency of harvesting light energy? A. Blue Algae B.Green Algae C.Red Algae D.Purple Algae The correct answer is C

What is a holdfast? A. A chemical that makes algae hold on stronger B. A structure that holds algae onto the ground C. A belt that goes around the center of algae D. A scientific name for algae’s leaves The correct answer is B

What is alternation of generation? A. When an organism switches siblings with another B. When parents alternate in watching their children C. Algae’s method of getting rid of difficult spores D. When algae switches back in forth between diploid and haploid generations The correct answer is D

Funguslike protists have centrioles and lack chitin in their cell walls. A.True B.False The correct answer is A

Slime molds are found in areas deep and rich in organic matter. A.True B.False The correct answer is A

Water molds produce thin filaments called - A. flagella B. tails C. hyphae D. gametophytes The correct answer is C