Chlamydomonas Prepared by: Juliet Marie Theresa M. Villar

Chlamydomonas Single celled green alga Grows in ponds, ditches, and wet soil believed to be primitive reproduces asexually by producing ZOOSPORES Reproduces sexually by producing ZYGOTES

Parts of Chlamydomonas

Life Cycle

Asexual Reproduction A mature cell of Chlamydomonas is a haploid The zoospores grow into mature haploid cells, completing the asexual life cycle. These daughter cells develop flagella and cell walls and then emerge as swimming zoospores from the wall of the parent cell that had enclosed them. Asexual Reproduction A mature cell of Chlamydomonas is a haploid It resorbs its flagella and then divides twice by mitosis, forming four cells (more in some species)

Sexual Reproduction MEIOSIS MITOSIS When the zygote breaks dormancy, Meiosis produces four haploid Individuals (two of each mating type) That emerges from the coat. They eventually grow into mature cells. MEIOSIS A mature cell of Chlamydomonas is a Haploid cell. This diploid zygote secretes a durable coat that protects the cell against harsh conditions Sexual Reproduction MITOSIS Fusion of the isogametes occurs slowly, forming a diploid zygote. After their release, gametes from opposite mating types (designated + and - ) pair off and cling together. Within the wall of the parent cell, mitosis produces many haploid Gametes.

Some added notes: ISOGAMY –literally means “a marriage of equals” SPOROPHYTE –diploid individual that produce individual cells called spores (zoospores) GAMETOPHYTE –haploid individual that produces gametes HETEROMORPHIC Generations –sporophytes and gametophytes are structurally different ISOMORPHIC Generations –sporophytes and gametophytes look alike, although they are different in chromosome number.