بسم الله الرحمن الرحيم

Algae

Lab 8

Algae : are alarge and diverse group of Photosynthetic ,

eukaryotic , plant-like organisms that use

chlorophyll in capturing light energy.but lack characteristic

plant structures such as leaves , roots , flowers ,

vascular tissue , and seeds.

General characteristics and ecology

Algae can be unicellular as well as multicellular ,large

and complex forms found in the ocean called seaweed.

Algae are usually found in damp places.most unicellular and colonial algae are aquatic , and float near the surface of

the water.

The seaweeds grow mostly in shallow marine water , but

some,such as the red algae, can grow quite deep in the ocean.

Reproduction

• Asexual Reproduction :

Ex: binary fission….. formation of spores• Sexual Reproduction :

Ex: Isogamy…….. Heterogamy

Euglena-Spindle-shaped. -No cell wall, thus changes shape as it moves.-Pair of flagella -Contains red eyespot.

Euglena gracilis

reservoir

pigment spot

contractile vacuole

flagellum

chloroplast

pyrenoid

nucleus

65µ

cell membrane

• Chlamydomonas-Common inhabitant of freshwater pools.-Pair of flagella . -Single, cup-shaped chloroplast .

Chlamydomonas

flagellum

contractilevacuoles

Pigment spot

nucleus

pyrenoid

chloroplast

cell wall

cytoplasm

Volvox A colony consists of cells with flagella

Spirogyra Common freshwater algae consisting of unbranched filaments of cylindrical

cells.

cell wall

cytoplasm

chloroplast

nucleus vacuole

Single cell of spirogyra

strand of cytoplasm

chloroplast

nucleus

cell wall

strand of cytoplasm

.

3D representation of spirogyra cell structure

Diatoms

Mostly unicellular in both fresh and salt water.

dsarar@ksu.edu.sa