Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 28 Protists. Ancestors to modern protists, plants, animals and fungi. Oldest known are 2.1 billion years old (acritarchs). – Most DIVERSE eukaryotes.

Similar presentations


Presentation on theme: "Chapter 28 Protists. Ancestors to modern protists, plants, animals and fungi. Oldest known are 2.1 billion years old (acritarchs). – Most DIVERSE eukaryotes."— Presentation transcript:

1 Chapter 28 Protists

2 Ancestors to modern protists, plants, animals and fungi. Oldest known are 2.1 billion years old (acritarchs). – Most DIVERSE eukaryotes – Most are unicellular – Most use cellular respiration – Fall into 3 nutritional groups: ingestive (animal like), absorptive (fungus like) and photosynthetic (plant like) – Most are motile with cilia or flagella – Vary in reproductive/life cycles (some asexual, some sexual)

3 Evolution of Eukaryotic Cell SYMBIOSIS: mitochondria and chloroplasts were originally small prokaryotes in larger cells (serial endosymbiosis theory)

4 Phylogeny: Difficult to classify 1. Archaezoa: lack mitochondria – Question: Does their ancestry precede mitochondrial evolution??? – 3 subgroups: diplomonads, trichomonads, microsporidians

5 2. Euglenozoa: flagellates – Euglenoids: characterized by anterior pocket from which flagella emerge, mostly autotrophic – Kinetoplastids: single large mitochondrion and kinetoplast housing extranuclear DNA Ex. African tse tse fly: spreads Trypanosoma that causes African sleeping sickness.

6 3. Alveolata: small membrane bound cavities (alveoli) under cell surfaces. – Dinoflagellates: component of plankton found near the water surface, most are unicellular, perpendicular flagella causes spinning motion, episodes of population growth called blooms – cause red tides that may be toxic. (fish kill) – Apicomplexans: animal parasites. Ex. Plasmodium: causes malaria – Ciliates: uses cilia to move and feed, live along in fresh water. Cilia may cover all of cell or may be clustered. Two types of nuclei: 1 macronucleus that divides by binary fission and micronuclei that combine by SYNGAMY (union of two gametes) for genetic variation.

7 Misc protists: – Rhizopods (amoebas): pseudopodia – Actinopods (helizoans): axopodia – Foraminiferans: marine, porous shell – Plasmoidial slime molds – Cellular slime molds

8 Stramenophilia Photosynthetic autotrophs and hetertrophs – Diatoms: yellow and brown, glasslike silica walls, reproduce asexually, live in plankton – Golden algae: yellow and brown carotene and xanophyll, biflagellated, live in plankton – Oomycota: water molds – Brown algae: multicellular, marine, brown pigments SEAWEEDS: Thallus (Plantlike body), holdfast (rootlike), stipe (stemlike) and blades (leaflike) Alternation of generations: diploid sporophyte releases haploid spores that develop into gametophyte, produces gametes that unite to make zygote that turns into diploid sporophyte.

9 Rhodophyta Red Algae: no flagella, many different pigments, most abundant in tropical oceans, alternation of generations is common

10 Green Algae Green chloroplasts, common ancestor with plants, mostly freshwater Form “pond scum” Most produce sexually


Download ppt "Chapter 28 Protists. Ancestors to modern protists, plants, animals and fungi. Oldest known are 2.1 billion years old (acritarchs). – Most DIVERSE eukaryotes."

Similar presentations


Ads by Google