Introduction to Algae, Slides of Algae and Fungi

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INTRODUCTION TO ALGAE

FOSSIL HISTORY OF ALGAE

Dates back to 3.5 billion years before present.

• First prokoratic unicelluler algae

Cyanobacteria: photosynthetic, without any complex

organization.

• Cells with complex organization evolved with nucleus and other

cellular organelles.

With the exception of the cyanobacteria,

algae are eukaryotes, that is, the insides of their cells are

organized into separate membrane-wrapped organelles,

including a nucleus and Mitochondria.

Both undergo photosynthesis. Which means they both

contain chlorophyll and they both can make their own food

(autotrophic).

They have the same life cycle called alternation of generations.

Plants and green algae share similarities in cell division.

Plants and green algae has similar biochemical characteristics

(same biosynthetic pigment; same cell wall component; same

carbohydrates storage material)

What do algae and plant share in common?

• Algae lack the roots, stems, leaves, and other structures typical of true plants

The photosynthetic portion of the alga is a thallus while the attachment

portion comprises hair-like rhizoids (holdfast) ----- Thallophytes

• Algae do not have vascular tissues ---- non vascular plants. No “pipes” to carry

fluids. An alga moves its materials strictly through diffusion and osmosis.

• Algae do not form embryos within protective coverings.

Mostly, sperm and eggs of algae fuse in the open water and the zygote develops

into a new plant without any protection.

For other plant groups the zygote develops into an embryo within the

protection of the parent plant. For this reason, all other plant groups are termed

Embryophytes.

Reproductive structures in algae

The gametes are produced within a single cell. There is no jacket of sterile cells

protecting the gametes.

Variations in pigments, pigments, and cell structure ( unicellular, colonial, and

multicellular forms).

How are algae different with higher plants?

Compare plants to algae

Has ability to store and regulate water loss because

of waxes and oils found on the plant called lipids.

Leaves are able to carry out photosynthesis on land.

In order to provide nutrients to those leaves plants

must be able to transport water and nutrients to

different parts of the plant ---- has vascular system.

Plants must have roots to take in those water and

nutrients from the ground.

Reproductive strategies, like the ability to produce

seeds, allow plants to live out of water.

The Reproductive System Of Algae

• The reproductive system of algae is not equipped with a

network of sterile cells that

• function to protect fertile cells.
• So all cells have the potential to become fertile and produce

offspring.

• The embryo is not formed in a special protective tissue
• produced by the parent.
• Algae can reproduce vegetatively, sexually, and asexually

Sexual-Gametes

REPRODUCTION OF ALGAE

Vegetative Cell divisions/Fragmentation:

Part of the filament breaks off from the

rest and forms a new one.

Asexual Reproduction

Zoospores after losing

their flagella, form

new filaments.

No sexual fusion

Stigma (eye spot), photoreceptile organel

Most algae form:

some sort of spore, often motile

Algae also : have sex,

often a very simple kind of sex

where the algae themselves act

as gametes

Sometimes very complicated with

egg and sperm-like cells.

Life cycle

Toughness:

• leathery, flexible

coralline red algae

CaCO

3

cell walls endure

waves pounding

Red algae grow from the intertidal zone

down to 900

Special adaptations

Many species with rapid growth(up to 0.5 m/day)

Tolerant of extremes:

• cold/hot
• dry/wet
• turbulence/currents/waves
  • shading

One of the classification models

of algae

Algae

Euglenoids Diflagellates Diatoms

Golden

Algae

Brown

Algae

Green

Algae

Red

Algae

Create

green and opaque

water problems

in aquariums

Major producer in

marine ecosystems

Zooxanthellae;

toxic blooms

(Red tides)

Major component

of Ocean’s minute

plankton

Ecological

importance

in cooler

ocean water

Ecological

importance

in tropical

ocean Reef

building

Clorophyta

Phaeophyt

a

Rhodophyta

Chrysophyta

Euglenophyta Phyrophyta Bacillariophyta