Chapter 29 - PROTISTS_freeman

Chapter 29 - PROTISTS_freeman - Chapter 29 ­ PROTISTS...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 29 ­ PROTISTS Chapter 29 ­ PROTISTS All eukaryotes that are not plants, fungi or animals. Summary *General characteristics of protists. *Why they are important? *How are protists studied? *Diversity and evolutionary advances. *Key lineages. General Characteristics *The first eukaryotes *Unicellular or colonial or “multicellular” *Habitats are wet or moist *Very diverse kingdom *Occur in high abundance *Paraphyletic group – i.e. do not include all of the descendents of a common ancestor. Importance *Cause diseases in plants and animals *Algal blooms – red tides infect marine life *Many are primary producers: *Act as a “Carbon (CO2) Sink” ***Global Warming *Diseases, Table 29.1 *Plasmodium – malaria *Trichomonas – trichomoniasis (STD) *Giardia – Giardiasis *Amoeba – amoebic dynsentery *Phytophthora – potato blight How are Protists Studied? *Phylogeny is based on: * Cell structure – nuclear envelope and other organelles classify them as eukaryotes. * rRNA and other genes are analyzed to divide the Kingdom into smaller groups. * Morphology, behavior and reproduction cycles are used to further classify 1 the kingdom. the kingdom. *Fig 29.8 – note position of fungi, plants and animals. Evolutionary Advances *Protists offer a clue to the origin of mitochondria and chloroplasts and perhaps other cell organelles. *Endosymbiosis Theory, fig 29.11 *An ancient eukaryote engulfs a bacterial cell *Instead of being digested the bacteria and host cell develop a “mutualistic” relationship. *Endosymbiosis *The host cell provides carbon for the bacteria and the bacteria provides ATP for the host. *The bacterial cell (proteobacteria) evolves into a mitochondria. *Chloroplasts are believed to have originated in the same way when cyanobacteria were engulfed by ancient eukaryotic cells. What is the Evidence that Supports the Endosymbiosis Theory? * of mitochondria and chloroplasts Size *Mitochrondria and chloroplasts reproduce by binary fission *Unique ribosomes and proteins *Double membranes *Some chloroplasts have peptidoglycans in outer membrane, all have chlorophyll a like cyanobacteria *Have their own genomes (circular piece of DNA) and can replicate themselves. Evolutionary Advances Cont’d *What do protists tell us about the evolution of eukaryotes? * Cells became larger. * Organelles or compartments developed. (Ex. Mitochondria, chloroplasts, lysosomes, peroxisomes, Golgi apparatus, ER, etc.) Evolutionary Advancements *What do protists tell us about the evolution of eukaryotes? 2 *Compartments also require some support or organization – cytoskeletons develop. *Protists include unicellular organisms, colonial organisms and primitive multicellular organisms. Multicellularity is an analogous trait among Eukaryotes. Diversity of Protists * Protection and support *Cell walls * Tests (shells) of cellulose, CaCO3, or SiO2 *Rigid internal skeletons *Feeding habits * Ingestive feeding: * Absorptive feeding: * Photosynthesis *Movement *Cell crawling ­ pseudopodia *Swimming * Cilia * Flagella – different action compared with bacteria *Both cilia and flagella have the same molecular structure and occur throughout the eukaryotic domain. *Reproduction *Alternating asexual and sexual cycles in many protists. *Sexual reproduction requires a haploid stage. *Different multicellular forms represent the haploid (gametophyte) and diploid (sporophyte) stages. In some, the haploid stage dominates, in others the diploid stage dominates. *Figs. 29.20 & 29.21 Key Lineages * Excavata ­ ?oldest protists, parasites that have lost their mitochondria. 2 groups: *Diplomonadida (2 nuclei) – *Giardia *Parabasalida (1 nucleus) – *Trichomonas 3 * Euglenida (Discicristata): unicellular, ½ are photosynthetic, eyespots, flagella **Euglena, *Trypanosoma * Alveolata – unicellular; 3 groups * Ciliata: 2 nuclei, cilia – *Paramecium * Dinoflagellata: cellulose skeletons, ½ are photosynthetic – red tides, “sparkling” waves * Apicomplexa: parasites – *Plasmodium (malaria) * Stramenopila – uni­ and multicellular, “hairy flagella” are unique. * Oomycota: cell walls of cellulose – potato blight. * Diatoms: silicone shells – diatomaceous earth * Phaeophyta: photosynthetic, brown algae (kelp) * Amoebozoa ­ no cell walls *Amoeba and slime molds * Foraminifera ­ CaCO3 tests *“Shelled amoebas” ­ chalk (White Cliffs of Dover), marble and limestone; oil deposits *Plantae? *Rhodophyta: red algae *Chlorophyta: green algae 4 ...
View Full Document

This note was uploaded on 09/08/2011 for the course BIOL 1403 taught by Professor Dini during the Fall '09 term at Texas Tech.

Ask a homework question - tutors are online