Kingdom Protista: Most diverse organisms Animal-like called protozoa Plant-like called algae –Do not have roots, stems, leaves –Both multi-cellular and uni-cellular –One of major producers of nutrients and oxygen
Classification of Algae classical schemes based on cellular properties
Algae eucaryotes that have chlorophyll and other pigments for carrying out oxygenic photosynthesiseucaryotes that have chlorophyll and other pigments for carrying out oxygenic photosynthesis lack well-organized vascular conducting systemlack well-organized vascular conducting system have simple reproductive structureshave simple reproductive structures phycologyphycology –study of algae
Distribution of Algae primarily aquatic –planktonic suspended in aqueous environment phytoplankton –algae and small aquatic plants zooplankton –animals and nonphotosynthetic protists –benthic attached and living on the bottom of a body of water –neustonic live at water-atmosphere interface
Distribution… some terrestrial –on moist surfaces –endosymbionts in protozoa, mollusks, worms, and corals –endosymbionts, epiphytes, and parasites of plants –associate with fungi to form lichens
Structure of the Algal Thallus (Vegetative Form) thallus (pl., thalli) –body of an alga
Algal Reproduction Asexual –fragmentation thallus breaks up and each fragment forms a new thallus –spores zoospores – flagellated motile aplanospores – nonmotile –binary fission mitotic nuclear division followed by cytoplasmic division
Reproduction… sexual –oogonia (s., oogonium) relatively unmodified vegetative cells in which eggs are formed –antheridia (s., antheridium) specialized structures in which sperm are formed –zygote product of fusion of sperm and egg
Green Algae Most diverse Major pigmentation is chlorophyll Most live in freshwater, some in oceans, moist soil, tree trunks, in snow, and even in fur of sloths Can reproduce sexually or asexually Have a complex life cycle
Chlorophyta (Green Algae) wide diversity of body forms –some have holdfasts reproduce both sexually and asexually
Unicellular forms: Chlamydomonas e.g., genus Chlamydomonas stigma – aids in phototaxis *fresh water alga
Colonial form Pandorina (simple colony) *16 cells. * Asexual by daughter colonies * Sexual by fusion of motile anisogametes and zygote gives motile zoospores and divided to form daughter colonies.
Colonial Green Algae Volvox sp. 500-5,000 cells arranged to form a hollow sphere Cells are connected by strands of cytoplasm, move together A few cells are specialized for reproduction New colonies develop w/in existing colonies
SPHERICAL COLONY OF HUNDREDS OF FLAGELATTED CELLS (colony is motile) ASEXUAL REPRODUCTION: –A SURFACE CELL DROPS INSIDE BALL AND BY MITOSIS PRODUCES DAUGHTER COLONY. –PARENT COLONY EVENTUALLY BURSTS TO RELEASE DAUGHTER COLONIES. CHLOROPHYTA--Volvox
Sexual Reproduction: Haploid heterogametes (egg and sperm) from within the parent colony. Sperm and egg fuse to form a diploid zygote. The zygote undergoes meiosis to produce 4 haploid nuclei within the zygote. Only one nucleus survives. It is released as a spore from the zygote and produces a new haploid colony by mitosis. CHLOROPHYTA--Volvox
Shows some DIVISION OF LABOR within the colony: Vegetative cells Sperm producing cells Egg producing cells Daughter colony-producing cells CHLOROPHYTA--Volvox
Order Volvocales - have flagellated cells and colonies with glycoprotein cell walls Family Volvocaceae - colonial, flagellated cells Volvox sp. - colony of algal cells, usually 500 or more, cells are biflagellated with the colony moving (swimming) as a unit. The spaces between the cell is filled with water and mucilage. The large cells inside are daughter colonies formed by cell divisions (asexual reproduction). Eventually colony ruptures releasing the daughter colonies.
Filamentous with spiral chloroplast in each cell Forms green scum in ponds Pyrenoids (sites of starch storage) occur in the chloroplast Asexual reproduction is by fragmentation of the filament. CHLOROPHYTA- CHLOROPHYTA- - SPIROGYRA
Sexual reproduction by conjugation of isogametes: –Two haploid filaments line up. –Conjugation tube forms between each adjacent pair of cells. –The contents of one cell moves through the conjugation tube and fuses with the contents of the other = diploid zygote. –Thick-walled zygospore forms from zygote. –The zygospore overwinters. CHLOROPHYTA--SPIROGYRA
–In spring, the zygospore undergoes meiosis to produce 4 haploid nuclei. Only one survives and divides by mitosis to make a new vegetative filament. SPIROGYRA CHLOROPHYTA-- SPIROGYRA
Colonial Green Algae Spirogyra sp. Freshwater Forms long thread like colonies called filaments stacked end to end
Asexual reproduction is performed by formation of daughter colonies which are produced by specialized reproductive cells called "gonidia" (singular, gonidium).
Sexual reproduction is oogamous. The gametes are differentiated into female and male gametes. Female gametes are non-motile and are called eggs and are formed in special reproduction these cells called "oogonia". The male gametes are small and motile each is provided with two flagella and is formed in special reproductive cells called "antheridia". When male gametes are liberated from the antheridium they are attracted with the eggs, and one succeeds in fertilizing the eggs. The zygote forms a thick wall and is transformed to resting zygospores which after a period can germination of the zygote.
Volvox may represent three evolutionary lines of development: *An increase in the number of cells of the colony. *The specialization of certain cells for reproduction. *Advancement in sexual reproduction from isogamy to oogamy.
Division: Euglenophyta *Euglenoids can be found in fresh water in which decaying organic matter is present. *The pigments, chlorophyll and carotenoids give the plant a green colour and are contained in plastids. Unlike the blue- green algae the cell possesses an organized nucleus.
Division Euglenophyta CHLOROPHYLL a and b carotenoids, xanthophylls Store food as PARAMYLON 1 TO 3 flagella NO cell wall PELLICLE submembrane protein (glucose polymer) fresh water habitats HAVE STIGMA photosensetive eyespot
Unicellular - Euglenophyta Ex. Euglena Found in ponds and lakes around the world Possess chloroplasts–photosynthetic(autotroph) Can also be heterotrophic and absorb decaying organic matter Two flagella Eyespot-cluster of red pigment-not a real eye No cell wall but have a pellicle Reproduce by binary fission
Reproduction Asexual reproduction by longitudinal cell division starting from the front end of the cell
Sexual reproduction No sexuality is known in Euglena.
Division: C h r y s o p h y t a *The Chrysophyta vary in colour from greenish yellow to golden brown as a result of the predominance of carotenes and xanthophylls. *The food reserves includes "leucosin" a complicated carbohydrate and oils, starch is not formed. In some members the cell wall consists of two overlapping halves and is impregnated with silica. *Members of this division vary in shape. They may be unicellular, motile; or the cells may form colonies, or they may be filamentous multicellular or tubular structure with many nuclei and no cross walls (coenocytes). ***The plants of this division are usually divided into three classes, the yellow green, golden browns and the diatoms.
Diatoms (Bacillariophyceae) : Diatoms are present in large numbers in almost all types of water: salt, brackish, and fresh. "jewels of the sea"
An accumulation on the ocean floor of the siliceous cell walls of diatoms has result in enormous deposits of fossils, which now on land are referred to as diatomaceous earth.
Usage of Diatomaceous earth * a carrier for liquid nitroglycerin in dynamite. * abrasive in toothpaste. *It is employed extensively in the filtration of liquids. *An excellent insulting material, especially at high temperatures, * in boilers and blast furnaces, small amounts of it in cement greatly increase the strength of concrete.
Structure of the diatom cell: Two major groups of diatoms are known the centrals in which the cell is usually rounded and pinnales in which the cell is elongated. Chemically, the wall composed of pectin and silica. The protoplast of a diatom consists of cytoplasm, a nucleus and one or several plastids bearing a golden-brown pigment that masks the chlorophyll. Food is stored in the form of oil. The cell contains a large central vacuole.
What are diatoms? Diatoms are single celled algae that have two hard coverings of silica, SiO2, (almost identical to opal). [2,3] The two sides are called the epitheca and hypotheca; they fit together like a box and lid or petri dish, the epitheca overlapping the hypotheca. 
Reproduction of Diatoms Two individuals come in contact within a mucilaginous envelop. The nucleus of each cell divides meiotically to form four haploid daughter nuclei out of these four nuclei in each cell, two nuclei then degenerate. The protoplast of each cell divides to form two gametes of unequal sizes each having a nucleus, gamates of one cell fused with the gametes of the other cell to form two zygospores. The two mate zygotes elongate to form auxospores, which develop valves and form new diatoms.
Phylum Phaeophyta – Brown Algaedusky plants Contain chlorophyll a and c & fucoxanthin a brown accessory pigment Dark yellow brown color Largest & most complex of the algae Found in cool, shallow coastal waters of temperate or arctic regions
Phaeophyta – Sagassum sp. Sargassum sp. – form huge floating mats many km long in an area known as the Sargasso Sea near Bermuda Also found on beaches of Caribbean and southern US
Phaeophyta – Giant kelp Giant kelp – grows to 60mGiant kelp – grows to 60m
Phaeophyta – Fucus sp. Fucus has a holdfast to anchor alga to bottom Body is of stipes - flattened stem like structures Blades are leaf like structures Gas filled bladders keep alga upright in water
PHAEOPHYTA-Brown Algae multicellular cold water seaweeds Fucoxanthin – brown pigment food stored as laminarin (future energy source?) source of iodine & algin – used in ice cream
most structurally complex algae shows tissue differentiation body is a flat thin thallus exhibit the Diplohaplontic Life Cycle (as do the higher plants) PHAEOPHYTA-Brown Algae
PHAEOPHYTA: Fucus Fucus (rockweed) has a flat and dichotomous thallus found in coastal waters holdfasts for anchorage air bladders for buoyancy receptacles contain conceptacles which produce gametes
Uses of Algae Major food source for life in the ocean – phytoplankton Produce much of the Earths oxygen through photosynthesis Nori-dried Poryphora – used to wrap sushi Carrageenan in ice cream, salad dressings, pudding, candy, chocolate milk Other products from algae - pancake syrup, egg nog Chemicals from algae are used in plastics, waxes, transistors, deodorants, paints, lubricants, artificial wood Agar derived from algae is used to thicken nutrient mixtures in labs used to grow bacteria