Life cycles of Protist

Done by: Shanice Smith

PROTIST Protist contains eukaryotes that are generally

regarded as identical or similar to the ancestors of modern plants, animals and fungi. It includes organisms which resemble early plants (algae), early animals (protozoa) and early fungi (oomycetes). It also includes a group known as slime molds which produces spores like fungi but creep slowly over surfaces and are therefore motile like animals.

Many protist can reproduce both sexually and asexually.

Asexual reproduction in

Protist

Many protists reproduce asexually. During binary fission; single protist cell divides into two cells.

Some protists reproduce by multiple fission, a form of cell division that produces more than one offspring.

Both types of fission produce offspring that are genetically identical to the parent cell.

Sexual reproduction in Protist Protists also reproduce sexually in

conjugation. During conjugation two individuals join and exchange genetic material stored in the small second nucleus. Then the cells divide to produce four offspring. The offspring are genetically different from the parent cells.

For many protist producers, the type of reproduction alternates by generation. For example, a parent may reproduce asexually, but its offspring may reproduce sexually. For other protist, sexual reproduction occurs only when environmental conditions are stressful.

Life cycle of Green Algae

Life cycle of Red Algae

Comparison of Red & Green Algae

☺They have an alternation of generations

☺They involve alternation of a haploid gametophyte generation with a diploid sporophyte generation.

Contrast of Red & Green Algae

Green AlgaeThey can be either unicellular or multicellular

Vegetative reproduction occurs by cell division, fragmentation and stolon formation

Asexual reproduction occurs by the formation of akinites or zoospores or aplanospores.

Sexual reproduction involves isogamy or anisogamy or oogamy.

Red AlgaeThey are mostly multicellular

Vegetative reproduction occurs by fragmentation.

Asexual reproduction involves the formation of motile zoospores and non-motile spores such as monospores and tetraspores

Sexual reproduction occurs by oogamy.

Life cycle of Paramecium

Life cycle of Sarcocystis

Comparison of Paramecium & Sarcocystis

They reproduce both sexually and asexually

Contrast of Paramecium and Sarcocystis

Paramecium Asexual reproduction

occurs by means of transverse binary fission or by budding.

They are free-living (non-parasitic)

Sexual reproduction is by conjugation. 

Sarcocystis☺Asexually reproduce is by the Sporozoites excysting from the sporocysts and invading the intestinal mucosa

☺They are parasitic

☺Their cycle begins when adult male and female parasites sexually reproduce in the definitive host's epithelial cells.

Life cycle of Saprolegnia parasitica

Life cycle of Phytophthora Infestans

Comparison of Saprolengnia and Phytophthora Infestans

☼They have both sexual and asexual reproduction.

Their sexual reproduction involves the production of antheridium and oogonium gametangia, which unite for fertilization.

Their asexual spore of saprolegnia releases motile short-living primary zoospores.

They have primary and secondary zoospores.

Contrast of Saprolengnia and Phytophthora Infestans

SaprologeniaThey infect freshwater fish and eggs.

Phytophthora InfestansThey infect plants

Referenceshttp://bioweb.uwlax.edu/bio203/s2007/benrud_jaco/index_files/Page5

21.htm

http://www.stanford.edu/class/humbio103/ParaSites2004/Sarcocystis/lifecycle.htm

http://tnfish.org/FishDiseasesParasites_TWRA/files/Saprolegnia.pdf

http://www.tutorvista.com/content/biology/biology-iii/kingdoms-living-world/algae.php

http://www.sparknotes.com/biology/microorganisms/protista/section1.rhtml