Transcript Chapter 28: Protists - structure, function, diversity, evolution, impact

Chapter 28: Protists - structure, function,
diversity, evolution, impact
Protists (Chapter 28)
1. More structural and functional diversity than any other
group of organisms…
2. Most are unicellular, some colonial and multicellular…
3. Most nutritionally diverse eukaryotes
A. photoautotrophs
B. heterotrophs
C. mixotrophs – combine photosyn with hetertrophic
nutrition
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Protists
Broken into three general categories based on ecological context:
1. Photosynthetic (plant-like) protists
- algae
2. Ingestive (animal-like) protists
- protozoans
3. Absorptive (fungus-like) protists
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Protists
How did such incredible diversity arise?
Many species resulted from two rounds of endosymbiosis…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Fig. 28.4
Phylogenetic tree showing the major clades of protists.
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Fig. 28.4
What’s a clade?
A complete branch of a phylogenetic tree. Above how many clades are highlighted?
Two, the blue and the red because these are complete branches. The green is not
complete.
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Euglenozoa
Characterized by spiral or
crystalline rod within flagella in
addition to 9+2 arrangement of
microtubules.
Cyrstalline structure has unknown
function.
Fig. 28.8
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Euglenozoa
Fig. 28.8
Phylum kinetoplastid
Ex. Genus Trypanosoma
- Causes sleeping sickness
- Spread by African tsetse fly
- Fatal if untreated
- Evade immune system by repeatedly changing the proteins on the surface of the cell
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Euglenozoa
Phylum euglenid
Ex. Euglena
- Found in freshwater
- Photoautotroph if sunlight available otherwise heterotroph by absorbing
nutrients from environment (mixotroph)
Fig. 28.8
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Characterized by sacs below
membrane called alveoli having
yet unknown function
Fig. 28.8
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Phylum dinoflagellates
- Abundant as both marine and freshwater phytoplankton
Phytoplankton – phyto = photosynthetic, plankton = “free-drifting”
- free-drifting photosynthetic organisms (cyanobacteria is also a
large part of phytoplankton)
- Bloom (explosion of growth) can cause “red tide”
- Secrete toxins that bioaccumulate in molluscs making them dangerous to eat
- Have internal “plates” of cellulose giving its characteristic shape…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Phylum Ciliates
- Obviously use cilia to move and feed
Ex) Paramecium
Two types of nuclei
- Large (macro) nucleus
- Smaller (micro) nucleus
- Can have more than one of each
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Phylum Ciliates
Macronucleus
- Contains dozens of copies of genome
- Genes are not on chromosomes (they don’t have chromosome)
- Arranged in small units each having many duplicates of a single gene
- The gene products (i.e. proteins) control daily functions like feeding,
waste removal, etc…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Phylum Ciliates
Feeding
- Mainly on bacteria, which are moved through oral groove and
phagocytosed at “cell mouth” into food vacuoles.
- Food vacuoles fuse with lysosomes
- Undigestable material is egested when lysosomes fuse with cell
membrane
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Alveolata
Phylum Ciliates
Reproduction
- Mostly asexually by “binary fission”
Conjugation
- Genetic diversity, NOT REPRODUCTION
- two organisms exchange haploid micronuclei (see fig 28.12b above and
use book for more detail)
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Diatom (Bacillariophytes)
- Unicellular Algae
- glass-like silica based cell wall as shown in figure
- Protection from predators
- Withstand pressures up to 1.4 million kg/m2 (pressure applied by the
leg of a table with an elephant standing upon it)
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Diatom (Bacillariophytes)
Reproduction
- Usually asexually by mitosis
- Sexual reproduction is not common, but does occur
Diversity
- Estimated 100,000 species
- Major component of phytoplankton in oceans and lakes
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Golden Algae (chrysophytes)
(chrysos = golden)
Dinobryon
- Contain yellow/brown cartenoid pigments
- Freshwater and marine plankton
- All obviously photosynthetic, some species mixotrophs
- Most unicellular, but some, as shown, are colonial
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Brown Algae (phaeophytes –
guess what phaeo means…)
Kelp
- Largest and most complex algae (its what you call seaweed)
- All are multicellular and most are marine (salt water – ocean)
- Common along temperate costs like ours
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Brown Algae
Sea palm (Postelsia)
Thallus
Kelp
- The body of the seaweed that is plant-like
- Basically, the holdfast, stipe (stem-like) and blades (leaf-like) (see above)
Holdfast
- root-like structure at base solely for anchoring, not absorption like roots
of plants
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Stramenopila
Phylum Brown Algae
Life-cycle: Alternation of Generations
This is important to understand
because as you might guess, since
plants evolved from multicellular
algae, they also do this.
Heteromorphic
- The two generations are
structurally different as opposed
to being isomorphic
Laminaria (a brown algae)
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Cercozoans and Radiolarians
- Amoeba with threadlike pseudopods
- Amoeba is a general term for a protist that uses pseudopodia to move and
feed. There is no one clade or kingdom that consists of amoebas
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Cercozoans and Radiolarians
Foraminiferans (Forams)
Radiolarian
- Foramen means “little hole”
- Tests made of silica
- Named for porous shells called tests
- Pseudopodia called axopodia
- Organic molecules hardened with CaCO3
- Pseudopodia extend through pores of shell and
fx in test formation, swimming and feeding
Both of these phyla consist of
amoebas because…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Amoebozoans
- Amoeba with lobe shaped rather than threadlike pseudopods belong to this clade:
Now this amoeba belongs to the above kingdom…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Amoebozoans
Phyla: Gymnamoeba
Phagocytosis of a ciliate:
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Were once thought to be fungus hence the name, but molecular evidence
has revealed convergent evolution
Two major types:
1. Plasmodial Slime Molds
2. Cellular Slime Molds
They in part by their life cycles…
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Plasmodial Slime Mold Life Cycle
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Cellular Slime Mold Life Cycle
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Phylogeny of protists
Let’s examine a handful of these clades…
Fig. 28.4
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Rhodophyta
Rhodo = red
Red Algae
Red due to pigment known as phycoerythrin, which masks chlorophyll
Most large and multicellular, living in tropical waters
Alternation of Generations
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Chlorophyta
Chloro = green
Green Algae
Much like plants, systematics has shown close relationship b/w green algae and
plants as you would expect…
Two groups - Chlorophytes and Charophyceans
1. Chlorophytes
- More than 7,000 species, most in fresh water
- Simplest are unicellular
- These are the ones that live in mutualism
with fungus to form lichen
Watermelon snow showing the
incredible diversity of chlorophytes
*Charophyceans and most related to land plants and are discussed at beginning of Ch. 29 with plants
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Chlorophyta
Chloro = green
Green Algae
Larger size and complexity arose via:
1. Colony formation (ex. Volvox)
and multicellular filament
formation.
2. Repeated division of nuclei
without cytoplasmic division
(ex. Caulerpa)
3. True multicellular forms with
cell division and differentiation
(Ex. Ulva)
Chapter 28: Protists - structure, function,
diversity, evolution, impact
Kingdom Chlorophyta
Chloro = green
Syngamy = fusion of gametes, aka
fertilization/conception
Green Algae
Complicated life cycle of asexual and sexual stages:
Chapter 28: Protists - structure, function,
diversity, evolution, impact