Algae

• Prokaryote,
• •No nuclear envelopes
• •No membrane-bound organelles, such as plastids, mitochondria, dictyosomes, endoplasmic reticulum

•Some by chemical reactions or by photosynthesis

• •Fission - No mitosis, DNA strand duplicates and is distributed to new cells.
• vNo sexual reproduction
• •Genetic recombination facilitated by pili or by close contact of cells.

• •Cyanobacteria contain phycobilins (blue and red pigments).
• •Cyanobacteria can both fix nitrogen and produce oxygen.

• Can live in extreme heat
• First photosynthic organism

• •Symbiotic with other organisms
• –Amoebae, sea anemones, fungi (producing lichens), cycads
• -mutialism.
• cycads have amoebae
• -can be found in fresh water as well

• •Often in chains, or colonies held together by gelatinous sheaths
• •Cells blue-green in color in about half of the approximately 1,500 species.
• •Produce nitrogenous food reserve - Cyanophycin
• •Flagella unknown

• •New cells by fission, or by fragmentation of colonies or filaments.
• •In Nostoc and Anabaena, fragmentation often occurs at heterocyst.
• –Heterocyst - Large colorless, nitrogen-fixing cell
• –Also produce akinetes
• oAkinetes - Thick-walled cells that resist adverse conditions

chloroplasts originated as cyanobacteria or prochlorobacteria living within other cells

•Fossils of cyanobacteria, 3.5 billion years old, found in Australia.

•3 billion years ago, cyanobacteria produced oxygen as by-product of photosynthesis.

•Oxygen accumulated in atmosphere, becoming substantial 1 billion years ago.

•As oxygen accumulated, other photosynthetic organisms appeared and forms of aerobic respiration developed.

•In last half billion years enough ozone for UV shield and for photosynthetic organisms to survive on land.

Cyanobacteria=plankton, in which other animals eat= food systems!

-algal blooms-poisonus to livestock

Food=spirolina

swimmers itch

nitrogen fixation

High amounts of phorphorous and nitrogen

• Microcystis produces
• the toxin microcystin. Aphanizomenon can produce
• multiple toxins including cylindrospermopsin, saxitoxin andanatoxin.

Green algae probably indirect ancestor of land plants.


 Shares features with land plants: cells that resemble parenchyma, development of cell plate and phragmoplast during mitosis, a protective covering for zygote, and production of lignin-like compound (helps make it woody=land plants)

All Eukarytoic cells

•Protista, Plantae, Fungi, Animalia

Kingdom Protista,

Protista is diverse and heterogeneous

Phylum Chlorophyta

•Unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves

• •Greatest variety in freshwater lakes, ponds, and streams
• –Some on tree bark, in animal fur, in snowbanks, in flatworms or sponges, on rocks, in lichen “partnerships.”
• •Have chlorophylls a and b
• •Store food as starch
• •Most have a single nucleus per cell.
• •Most reproduce both sexually and asexually.

• Green Algae
• •Common inhabitant of freshwater pools
• •Unicellular (acellular?)Pair of whip-like flagella on one end pull cell through water-(helps this plant move)

• •Two or more vacuoles at base of flagella
• –Regulate water content of cell and remove waste
• •Single, cup-shaped chloroplast with one or two pyrenoids inside
•      –Pyrenoids - Proteinaceous structures associated with synthesis of starch
• •Red eyespot near base of flagella
•       –Allows alga to swim toward light

Haploid is the basal state

• –Nucleus divides by mitosis, and cell contents become two daughter cells within cellulose wall.
•  
• Each develop flagella and swim away.

•  No change in chromosome number; all cells remain haploid.
• -budding, spliting

Gametes fuse to form a diploid zygote. becomes zygospore, undergoes meiosis internally and split off haploid cells

-Sooo only diploid for a very short amount of time.

-Green Algae,

• •Filamentous with holdfast cell at one end
• •Chloroplast - Wide, curved, somewhat flattened, with one to several pyrenoids.

Reproduces asexually and sexually.

• –Cells contents condense, divide by mitosis and become zoospores inside parent cell.
• –Zoospores escape through pore in parent cell wall.
•   Resemble Chlamydomonas cells
•   Grow into new filaments

• •Each new cell produces flagella.
• •Cells escape from parent cell and become gametes.

Green algae

• •Filaments of cylindrical cells
• •Chloroplast ribbon-shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals.

Asexual- breaks off and creates a new holdfast cell.

• Sexual- By Conjugation
• –Papillae fuse and form conjugation tubes.
• –Protoplasts fuse, forming zygote that develops thick wall.
• –Eventually zygote undergoes meiosis.

Green algae- with holdfast

•Large netlike chloroplast with pyrenoids at intersections of net

Asexual-fragmentation breaks apart grows new filamentous

• -most of lifecycle is haploid.
• -diploid is mostly just at the zygote, which splits open to produce haploid cells.
• -Oogamete= female cell with egg=
• - Antheridium= produces and releases sperm.
• -Zygote produces 4 zoospores by meiosis that grow into new haploid filaments

Chorella- used for food source, that can be grown in culture. -only asexually

• Desmids= important part of plankton
• -reproduce by conjugation.

Green Algae, hexagonal meshes.

• -
• –Asexual reproduction, as well as isogamous sexual reproduction
• –Isogamous = two flagellated gametes

•  
• - Colonial green algae held together in a secretion of gelatinous material, resembling hollow ball

• –Reproduction asexual or sexual
• oSmaller daughter colonies formed inside parent colony

• (sea lettuce) - Multicellular seaweed with flattened green blades and basal holdfast to anchor blades to rocks
• –Haploid and diploid blades

• oDiploid blades produce spores that develop into haploid blades.
• oHaploid blades bear gametangia that form gametes. Gametes fuse to form zygotes that grow into diploid blades

Exhibit isomorphism - Haploid and diploid blades indistinguishable

Phylum Chromophyta

Yellow-brown algae

• –Oogamous, coenocytic, filamentous species
• oAplanospores formed during asexual reproduction.Sexual reproduction rare
• -Two flagella of motile cells are oriented in opposite directions

• –Motile cells have two flagella of unequal length inserted at right angles to each other.
• oPhotoreceptor on short flagellum.

• •Unicellular
• •Fresh and salt water, particularly abundant in cold marine habitats
• •Also, dominate algal flora on damp cliffs, tree bark or buildings

• •Look like ornate, glass boxes with lids
• –As much as 95% of wall is silica.
• •Chlorophylls a and c and fucoxanthin
• •Food reserves - Oil, fats or laminarin

•Original cell size restored through sexual reproduction.

• •Most marine; majority in cold, shallow water
• •Many have a thallus differentiated into a holdfast, a stipe, and blades.
• –Blades may have gas-filled bladders.
• •Chlorophylls a and c, fucoxanthin
• •Food reserve = laminarinAlgin in cell walls

• •Sargassum - Floating brown seaweed
• •Asexual reproduction by fragmentation or autospores.

Brown algae, common rockweed

• –Sexual reproduction:
• oReceptacles at tips of branches contain spherical chambers called conceptacles with gametangia inside.
•  Oogonium produces 8 eggs.
•  Antheridium  produces 64 sperm.
• oEggs and sperm released into water.

Phylum Rhodophyta.

•In warmer and deeper waters than brown algaeMost are filamentous with filaments so tightly packed they appear to have flattened blades or branched segments

• •Relatively complex life cycle involving three types of thallus structures
• •Nonmotile reproductive cells

Brown algae

• –Similar to those of cyanobacteria
• oRed algae may have been derived from cyanobacteria.
• •Chlorophylls a, and sometimes d
• •Food reserve - Floridean starch
• •Numbers of species produce agar.

Dinophyta

• vThe Dinoflagellates
• •Red tides - Sudden multiplication of dinoflagellates
• –Some produce neurotoxins that accumulate in shell fish.
• •Cellulose “armor plates” inside cell membrane
• •Two flagella in intersecting grooves
• –One trails behind cell - Acts as rudder

• –Contain xanthophyll pigments
• –Chlorophylls a and c
• •About 45% nonphotosynthetic
• •Chromosomes remain condensed and visible throughout life of cell.
• •Starch food reserveMany have tiny projectiles that fire when irritated

• vDiatoms
• •Oils are sources of vitamins.
• •Diatomaceous earth
• –Filtration
• –Polishes, toothpaste
• –Paint that reflects light
• vOther algae
• •Chlorella
• –Potential human food source

• –Ice cream, salad dressing
• –Latex paint, textiles, ceramics
• –Regulates water behavior
• oControls development of ice crystals
• oRegulates penetration of water
• oStabilizes suspensions

• •Iodine from kelp
• •Red algae
• –Food - Dulse, nori
• –Carrageenan - Thickening agent
• vAgar
• •Produced by red alga Gelidium
• –Solidifier of nutrient culture media
• –Retains moistness in bakery products
• –Base for cosmetics