ALGAE. Biol 165: Diversity of Life :24 PM

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1 Biol 165: Diversity of Life :24 PM ALGAE Introduction Eukaryotic Algae are members of the Kingdom Protoctista Cyanobacteria is a Prokaryotic bacterial Algae, and part of the Domain Bacteria, NOT Eukaryota Photoautotrophs: fix carbon by photosynthesis, using Chlorophyll and accessory pigments to convert solar energy into chemical (usable) energy. o often, the accessory pigments are used to classify groups Algae were once grouped with Kingdom Plantae Algae (and the term) are polyphyletic their host cells for chloroplasts belong to different supergroups of protists. The Chloroplast of Algae originated from an endosymbiotic cell of a prokaryote Cyanobacteria. o 3 Phyla evolved from primary capture of a cyanobacteria with a chloroplast it has 2 membranes around the chloroplast o All other Phyla acquired their chloroplast through secondary capture events involving a red algae - chloroplasts have 3 or more membranes. o Algae can range in size from small unicellular organisms to colonial, etc. Life cycles can often include asexual and sexual phases, and show alteration of generations. Red Algae Phylum Rhodophyta o 5-6k species o unicellular to filamentous(pseudoparenchymatous) forms o some encrusted with calcium carbonate o Most are marine, some freshwater, few terrestrial. o Chlorophyll a & phycoerythrin and phycocyanin accessory pigments.

2 o Thylakoids are not stacked o Floridian Starch for storage o No motile cells (not even the gametes) o Essentially Oogamous life cycle, 3 phases 1 Gametothallic (1n gametophyte) stage; has antheridium(sperm) and carpogonium (egg) 2 Sporothallic (2n sporophyte) stages; 2n Carposporothallus (fertilized egg w/ sperm). 2n Tetrasporothallus arises from carposporothallus when it falls on ground The Gametothallus and mature Tetrasporothallus look the same you cannot differentiate them with the unaided eye. o cell wall composed of cellulose, pectin, and colloids o used commercially as a thickening agent is products such as icecream, cheese, jelly, etc. Genus Euglena: Single celled organism; basal flagellate Most live in freshwater, some marine. they have two flagella a long, and a short one some are NON-photosynthetic (~ ½ ) the photosynthetic variety contain Chlorophyll a & b, and carotenoids/xanthophylls. Their chloroplasts have 3 membranes and are stacked. have a pyrenoid: protein-rich structure containing rubisco have an eye spot and light detector to avoid the bright lights. some species are mixotrophs. reproduce asexually carbohydrate is stored as glucose polymer paramylon granules. If grown in the dark they can lose their chlorophyll, but regain it again if exposed to light conditions. They lack a cellulose wall. They are spirally twisted and surrounded by a pellicle.

3 Phylum Dinoflagellata From supergroup Chomoaveolata Some Chlorophyllous and some non-chlorophyllous also known as Dinophyta or Pyrrophyta Had a different host symbiont that other chromophytes (unknown). Have plate-like vesicles on outer margin of cells. DNA has 5-hydroxymethyluracil instead of Thymine. Food reserved as STARCH if present, thylakoids are present in stacks Often have trichocysts that discharge from cell surface (rod-like). Mostly asexual reproduction and [rarely] sexual reproduction ~30 species use bioluminescence. Most common genera are Peridinium and Ceratium Some are endosymbionts of reef-building corals; see genus Symbiodinium and Tridacna. Some are parasitic Blooms produce RED TIDES along coasts of N. America and Japan kill many fish during blooms. toxins produced by dinoflagellates accumulate in filtering shell-fish, and can cause serious illness in humans o PSP = Paralytic shellfish poisoning o Ciguatera toxin producted by Gambiergiscus. Chromista Supergroup Chromalveolata Chromista is a monophyletic group of divisions that share distinctinve DNA, ultrastructures, and biochemical traits It is thought they acquired their chloroplast through SECONDARY capture of a RED ALGA. Algal members are called Chromophytes because they have chlorophyll c, and various brown/yellow/gold accessory pigments. o xanthophylls, fucoxanthin, and xanthins; xanth = yellow They have heterokontous zoospores at some part of their life cycle

4 o zoospores: a spore of certain algae, fungi, and protozoans, capable of swimming by means of a flagellum. o herterokontous (or stramophiles): refers to the motile life cycle stage, in which the flagellate cells possess two differently shaped flagella; one long tinsel flagella, and one short whiplash flagella. This is a SYNAPOMORPHY of the group. Phylum Haptophyta and Chryptophya are likely basal to the entire SuperGroup Chromalveolata. Phylum Bacillariophyta Diatoms of SuperGroup Chromaveolata, Chromista Clade A chromophyte clade with 2ndary chloroplast capture from red alga. Chlorophyll a & c, xanthophylls and carotenoids o golden-brown They look like little boxes, and are referred to as Frustules (their whole structure. Look like two lids fitting together (epithica-top, and hypothecabottom); where the two lids join is called the girdle band Mostly reproduce asexually: the epitheca and hypotheca separate, and form new partner lids. Only after becoming two small from asexual division do they reproduce sexually; o anisogamous dissimilar gametes; sperm heterokontous, egg often larger and not motile. Frustules are not easily biodegradable and can be found in geographical deposits dating ~150mybp. Marine deposits form DIATOMACEOUS EARTH, which is used as water filters, in deodorants, toothpaste abrasives, etc. have silica and pectin cell wall. Phylum Chrysophyta Golden/Brown Algae SuperGroup Chromalveota, Clade Chromista Chromophyte 2ndary capture of chloroplast from red alga. Heterokontous; unicellular and simple colonial

5 Mostly freshwater plankton Primary storage is Chrysolaminarin. Morphologically very diverse Form silaceous cysts around them to permit overwintering these scales fossilize and occur as early as upper Cretaceous period. Appear to be closely related to Bacillariophyta and Xanthophyta. ie, Genus Synura and Dinobryon. Phylum Phaeoppytha Brown Algae Brown algae are the largest and most morphologically complex of Protoctistans. 265 genera; 1500 spp. Mostly Marine in rocky coastlines Range from microscopic filamentous to macroscopic pseudoparenchymous forms (100m in length). NO UNICELLULAR FORMS Chlorophy a & c is MASKED by FUCOXANTHIN, as well as other accessory pigments. Food reserve is Laminarin Alginic acids make up 10-25% of dry weight used commercially 3 life cycles can be observed, depending on species o 1) Alternation of isomorphic generations: sporothallus and gametothallus look the same to the unaided eye. o 2) Alternation of heteromorphic generations: sporothallus and gametothallus look considerably different. o 3) Oogamous mode of reproduction in Sporothallus Isogenerate Life Cycle of Genus Ectocarpus o Isomorphic alternation of generations o gametes are isogamous - sperm and egg look the same and are both heterokonts. Heterogenerate Life Cycle of Genus Laminaria (KELP). o heteromorphic alternation of generation sporothallus and gametothallus look completely different

6 o still isogamous egg and sperm are identical heterkonts to the unaided eye. o Alginic acid obtained for commercial purposes. Unithallic Life Cycle of Genus Fucus o NO alternation of generations no gametophyte o fertilization is oogamous, therefore gametes are NOT isogamous (look the same) Sperm is heterokontous o Abundant along coasts of Atlantic Ocean o Since they grow along intertidal zone, they are exposed to air twice daily (with tides), but they adapted and are dominant in these areas o Alginic acid from Fucus is also used for commercial purposes. o Phylum Chlorophyta Green Algae Chloroplast is derived from a PRIMARY endosymbiotic event (unlike Chromophytes). o likely from Prochloron a cyanobacteria Chloroplasts in stacked thylakoids of 2-6 No peripheral envelope of ER Grouped with SuperGroup Plantae, Chloroplastida clade. Have Chlorophyll a & b, and carotenoids Food reserve is STARCH If flagellated, have 2-4 flagella have a variety of types of life cyles Class Chlorophyceae Flagellated and colonial isogamous to oogamous Can use asexual or sexual reproduction o Genus Volvox Oogamy o

7 Class Ulvophyceae Isomorphic Alternation of generations Isogamous or Anisogamous Class Charophyceae Genus Spirogyra o Conjugating multicellular Filaments o Male and Female filament are isogamous o They pair together and form numerous conjugation tubes between them (looks like a ladder). Scaliform conjugation cell contents move to one side (filament), fertilization occurs and zygote is on one side (often in female filament side). Lateral conjugation contents of both male and female cell meet in the middle conjugation tube, and zygote is positioned in conjugation tube Charophytes are primitive members of Kingdom Plantae o Coleochaete has a sheath of gametothallus cells around egg/zygote (oogamous) o Chara has antheridia and archegonia, similar to modern plants, and is also oogamous