Algae reproduction - sd41blogs.casd41blogs.ca/lamd/files/2019/04/Lesson-6_Algae-Reproduction-Notes.pdfFILAMENTOUS ALGAE •Filaments are long threadlike colonies of green algae •They

ALGAE REPRODUCTION

CHLAMYDOMONAS•Nucleus – control centre, controls processes

within Chlamydomonas

•Eyespot - detects light and darkness

•Pyrenoid – synthesis and storage of starch

•Chloroplast – where photosynthesis occurs

• Starch – food source

•2 Flagella – whip-like structures for movement

COLONIAL GREEN ALGAE• In a colony:

–Many cells live together but function independently

–Cells do not form specialized tissues/structures

– If the colony is broken apart each cell can live and grow into a

new colony

–Examples: Volvox and Gonium

• Volvox = most cells are identical except a few cells that specialize in the

production of gametes

–Colony cells can communicate through cytoplasm to move the

colony

• Cells are connected by strands of cytoplasm

FILAMENTOUS ALGAE• Filaments are long threadlike colonies of green algae

•They do not have an asexual life cycle

• If an algae filament is broken it can regrow

–Vegetative fragmentation

•Reproduce sexually by conjugation

•Example: Spirogyra and Oedogonium

CONJUGATION

CONJUGATION• Two haploid filaments line up so that they touch each

other

• Small bumps grow out from each cell, forming bridges

between each pair of cells

–Bridges are called conjugation bridges or conjugation canals

• The cell walls dividing the bridges then dissolve

• Creates a passageway between the cells

• Contents of cells in one filament enter the cells of the

other filament

CONJUGATION• Transfer of gametes from one strand to the other results in one filament of empty cells and one filament containing zygotes

• Zygotes separate from each other and develop thick cell walls

–This creates a zygospore

• Zygospore = a diploid spore

–When conditions are favourable, each zygospore eventually grows into a new Spirogyra filament

• The zygospore will undergo meiosis to produce haploid cells

CONJUGATION VIDEO

•https://www.youtube.com/watch?v=fZYAVIRedzM

MULTICELLULAR GREEN ALGAE –ULVA (SEA LETTUCE)

MULTICELLULAR GREEN ALGAE –ULVA (SEA LETTUCE)

• Diploid sporophyte undergoes meiosis and produces haploid spores

• Haploid spores develop into haploid gametophytes through mitosis

• Gametophytes produce haploid gametes which can grow into other haploid gametophytes (asexual reproduction)

• If male and female haploid gametes meet and fuse they form a diploid zygote which develops into a diploid sporophyte

• Typical alternation of generations