Chapter 22 Protists
Chapter 22: Protists
22-1: Characteristics of Protists
Protists Are a Varied and Ancient Group of Organisms
Protists are the most diverse of all organisms - most are unicellular - microscopic - few are complex and multicellular
Characteristics
- eukaryotes - some photosynthesis - some ingest their food - some absorb their food - some have flagella or cilia o used for locomotion or getting food - found almost everywhere there is water - damp soil and sand - some are parasitic - most have mechanisms for monitoring and responding to their environment - some have eyespots o small organelles containing light-sensitive …show more content…
sexual reproduction 2. multicellularity
Many protists reproduce only asexually – mitosis. Some use meiosis and sexual reproduction only in times of stress and then others reproduce sexually most of the time.
What unites protists?
The kingdom Protista contains all eukaryotes that don’t fit in animals, plants and fungi.
See table on page 479 for distinguishing one phyla of protists from another.
Generally protist that are heterotrophic are called protozoan and photosynthetic protists are called algae.
Protists Reproduce Sexually and Asexually
Typically unicellular protists reproduce by forming complex colonies. Chlamydomonas species reproduce sexually and asexually. The single-celled protist is haploid and reproduces asexually by absorbing its tail and dividing by mitosis. Mitosis produces two to eight haploid cells called zoospores. Many zoospores break out of the parent cell and grow to become mature haploid cells.
Sexual reproduction among unicellular protists
During environmental stress certain protists reproduce sexually - haploid cells divide by mitosis producing haploid gametes - a pair of gametes fuse to form a …show more content…
Ciliates – phylum Ciliophora - have large numbers of cilia = tightly packed rows of short flagella used for movement - complex unicellular heterotrophs - body walls are tough but flexible – can squeeze through or around many obstacles - form vacuoles for ingesting nutrients and regulating their water balance - most have two nuclei o micronuclei = contains normal chromosomes that divide by mitosis o macronuclei – contains small pieces of DNA derived from micronuclei used in routine cellular functions - reproduces by mitosis – splitting in half - can engage in sexual reproduction by conjugation
Protists Molds Are Not Fungi
Protistan molds are heterotrophs with some mobility. They have cell walls made of carbohydrates.
Cellular slime molds – phylum Acrasiomycota - move through soil and digest bacteria - during environmental stress they gather together forming multicellular colonies called slugs - slugs develop a base, a stalk and a swollen tip that develop spores - each spore becomes a new organism and begins to
22-1: Characteristics of Protists
Protists Are a Varied and Ancient Group of Organisms
Protists are the most diverse of all organisms - most are unicellular - microscopic - few are complex and multicellular
Characteristics
- eukaryotes - some photosynthesis - some ingest their food - some absorb their food - some have flagella or cilia o used for locomotion or getting food - found almost everywhere there is water - damp soil and sand - some are parasitic - most have mechanisms for monitoring and responding to their environment - some have eyespots o small organelles containing light-sensitive …show more content…
sexual reproduction 2. multicellularity
Many protists reproduce only asexually – mitosis. Some use meiosis and sexual reproduction only in times of stress and then others reproduce sexually most of the time.
What unites protists?
The kingdom Protista contains all eukaryotes that don’t fit in animals, plants and fungi.
See table on page 479 for distinguishing one phyla of protists from another.
Generally protist that are heterotrophic are called protozoan and photosynthetic protists are called algae.
Protists Reproduce Sexually and Asexually
Typically unicellular protists reproduce by forming complex colonies. Chlamydomonas species reproduce sexually and asexually. The single-celled protist is haploid and reproduces asexually by absorbing its tail and dividing by mitosis. Mitosis produces two to eight haploid cells called zoospores. Many zoospores break out of the parent cell and grow to become mature haploid cells.
Sexual reproduction among unicellular protists
During environmental stress certain protists reproduce sexually - haploid cells divide by mitosis producing haploid gametes - a pair of gametes fuse to form a …show more content…
Ciliates – phylum Ciliophora - have large numbers of cilia = tightly packed rows of short flagella used for movement - complex unicellular heterotrophs - body walls are tough but flexible – can squeeze through or around many obstacles - form vacuoles for ingesting nutrients and regulating their water balance - most have two nuclei o micronuclei = contains normal chromosomes that divide by mitosis o macronuclei – contains small pieces of DNA derived from micronuclei used in routine cellular functions - reproduces by mitosis – splitting in half - can engage in sexual reproduction by conjugation
Protists Molds Are Not Fungi
Protistan molds are heterotrophs with some mobility. They have cell walls made of carbohydrates.
Cellular slime molds – phylum Acrasiomycota - move through soil and digest bacteria - during environmental stress they gather together forming multicellular colonies called slugs - slugs develop a base, a stalk and a swollen tip that develop spores - each spore becomes a new organism and begins to