Amoeba hunts and kills paramecia and stentor Eukaryotic photosynthetic cells 1
Eukaryotic organelles are odd in many ways Organelles: membrane bound compartments in a cell Nucleus, chloroplasts, and mitochondria are organelles that each bounded by double membranes Both chloroplasts and mitochondria Have their own circular DNA Have their own bacteria-like ribosomes Reproduce via binary fission similar to prokaryotes Phylogeny from nuclear DNA a-proteobacteria Red algae Cyanobacteria Green plants Brown algae All Living Organisms 2
a-proteobacteria Red algae Cyanobacteria Green plants Brown algae Eukaryotic Nuclear DNA All Living Organisms Eukaryotic DNA sequences from chloroplast and mitochondrion are nested in prokaryotic lineages Chloro plast DNA Mitochondrial DNA a-proteobacteria Cyanobacteria Red algae Green plants Brown algae Nuclear DNA All Living Organisms 3
Endosymbiosis symbiotic relation in which one organism resides inside the cells of another Chloro plast DNA Mitochondrial DNA a-proteobacteria Cyanobacteria Red algae Green plants Brown algae Nuclear DNA All Living Organisms The endosymbiosis theory 4
The endosymbiosis theory The endosymbiosis theory 5
The endosymbiosis theory Integration: Loss of bacterial cell wall Transfer of most genes from both the mitochondrion and the chloroplast to the nucleus The endosymbiotic theory explains. a. the origin of eukaryotes b. how cells reproduce c. how bacteria live d. the differences between plant and animal cells 6
All organelles in eukaryotic cells are thought to have evolved from endosymbiosis. a. true b. false Which of the following statements about the endosymbiotic theory is FALSE? a. The entire genome of the ancestral bacteria has been preserved in present-day mitochondria and chloroplasts b. Both chloroplasts and mitochondria have their own circular DNA c. Mitochondria and chloroplasts both arose from freeliving bacteria d. Chloroplasts have two membranes: the inner membrane is derived from the bacteria and the outer one from the endocytic vesicle 7
Primary endosymbiosis resulted in green algae, red algae and glaucophytes. Secondary endosymbiosis: A eukaryotic heterophic cell engulfed a green or red algae. This would lead to chloroplasts with four surrounding membranes: the endocytic membrane, the green/red algae PM, the two algal chloroplast membranes Sometimes one of these four membranes are lost, and sometimes the entire chloroplasts are lost Seven major lineages of eukaryotes Heterokonts 8
Eukaryotic lineages are ancient Heterokonts : Single celled or simple multicellular (without much cellular differentiation) eukaryotic organisms that cannot be classified as plant, fungal, or animal. An artificial collection of organisms, not monophyletic (monophyletic: include all taxa descended from a single ancestor). Heterokonts Some are protists 9
Photosynthetic protists are called algae. The chloroplasts in algae can from primary, secondary, or even tertiary endosymbiosis Heterokonts Some are protists Seven major lineages of eukaryotes Heterokonts 10
Alveolates - contain alveoli (tiny membrane enclosed sacs beneath the plasma membrane). All unicellular, many are photosynthetic Ciliates: most are heterotrophic. All have numerous cilia. Paramecium Apicomplexa all parasitic, not photosynthetic. Plasmodium (malaria). Dinoflagellates Paramecium plasma membrane, showing alveoli Ciliates: Paramecium Dinoflagellates: Most are marine and are important photoautotrophic primary producers Chloroplasts surrounded by 3 or 4 membranes that may contain remnant nuclei Some are photosynthetic endosymbionts that live within the cells of other organisms, such as corals (invertebrate animals) Endosymbiotic dinoflagellates in coral cell Coral Bleaching by expelling dinoflagellates 11
Dinoflagellates: movement with two two flagella Dinoflagellates produce red tides. Some produce toxins that can kill fish, marine mammals and even humans. bioluminescent 12
Seven major lineages of eukaryotes Heterokonts Heterokonts: Two flagella, rows of hairs on the longer one Chloroplasts have 4 surrounding membranes through eukaryotic cells engulfed whole red algae. But not all heterokonts are photosynthetic. Diatoms, brown algae, and oomycetes Diatoms are common in fresh water 13
Diatoms Unicellular Photosynthetic Lack flagella except in male gametes Cell walls made of silica embedded in a pectin matrix. Cell wall is constructed in two pieces like a petri dish Diatoms are marine phytoplankton and can be incredibly productive. They are an important first tier of the food chain. Brown algae Marine algae, abundant in cool shallow water Kelps are some of the most complex brown algae. stipe blade bladder holdfast 14
Oomycota Previously classified as fungi because they have hyphae, produce spores and lack chlorophyll. However, they have cellulose cell wall, and swimming spores with two flagella Absorptive heterotrophs Most live in soil or fresh water and are decomposers. Water molds, downy mildews, and potato blight The filaments of a water mold radiate from the carcass of a beetle Seven major lineages of eukaryotes Heterokonts 15
Excavates: Euglenoids Usually single-celled, usually live in fresh water, no cell wall, two flagella, red or orange organelle called an eyespot Some species contain chloroplasts (three membranes from eukaryotic cell engulfed a green algae). Some are parasites (sleeping sickness) Euglena Seven major lineages of eukaryotes Heterokonts 16
Amoebozoans use lobe-shaped pseudopods for locomotion Amoebas crawl around and engulf food. They also have bacteria as symbionts some acting as mitochondria. Amoeba hunts and kills paramecia and stentor Amoebozoans: slime molds Can form a wall-less mass of cytoplasm with numerous nuclei. Move like a slug and produce fruiting bodies and spores like a fungus. 17
Major groups of algae Dinoflagellates Heterokonts Brown algae, diatoms Euglenoids Red algae, green algae, glaucophytes primary endosymbiosis secondary endosymbioses tertiary endosymbioses * * * * * * = dinoflagellates 18
Plantae, primary endosymbiosis secondary endosymbioses tertiary endosymbioses * * * * * * = dinoflagellates primary endosymbiosis secondary endosymbioses Excavates tertiary endosymbioses * * * * * * = dinoflagellates 19
primary endosymbiosis secondary endosymbioses tertiary endosymbioses * Diatoms and brown algae * * * * * = dinoflagellates primary endosymbiosis secondary endosymbioses tertiary endosymbioses * * * * * * = dinoflagellates Alveolates 20
Chloroplasts of these algae groups are from primary endosymbiosis except a. Green algae b. Red algae c. Brown algae d. Glaucophytes Lecture 16 Study Guide Define a protist. Are any protists photosynthetic? Define endosymbiosis. What are the evidences supporting the endosymbiosis theory? Which protists have alveoli and what are alveoli? Name two examples of heterokonts Name an example of Excavates Name an example of Amoebozoans Name one human disease caused by a euglenoid 21
Phytophthora infestans causes potato \ blight, it is an organism that has hyphae, produces spores and lacks chlorophyll. It has cellulose cell walls and swimming spores. What group of protists does this organism belong to? What are the groups of algae derived from primary endosymbiosis? Name two groups of algae derived from secondary or tertiary endosymbioses 22