Chapter 27 l Prokaryotes and the Origins of Metabolic Diversity.
Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
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Transcript of Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
PROKARYOTES (CHAPTER 27)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
Gram positive vs Gram-negative prokaryotes
Why are they called “gram-positive” and “Gram-negative”?
Bacteria come in two flavors:
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
A simple procedure used to stain bacteria:
Gram Staining
The thick peptidoglycan cell wall of gram-positive bacteria prevents the stain (crystal violet-iodine) from leaving the cell when decolorization is carried out.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
Penicillin
Taking advantage of the peptidoglycan cell wall:
Antibiotic that inhibits enzyme DD-transpeptidase, which is involved in building and rearranging the cell wall.
DD-transpeptidase with penicillin bound:
penicillin
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
CapsulesCapsules surround cell walls of many prokaryotes.
- Composed of polysaccharide or protein
Function:
Structure:
- Allows bacteria to bind to other bacteria or to another substrate like your cells.
- Protection from immune system
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactStructure of Prokaryotes
Fimbriae and Pili
Function:
- Allows bacteria to bind to other bacteria or to another substrate like your cells.
- Sex pili are specialized pili used during conjugation.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactMotility of Prokaryotes
Flagella
- 50% of prokaryotes capable of directional movement.
- Flagella are most common, but not the only means of motility
- NOT covered by plasma membrane like in eukaryotes.
- Basal apparatus (motor proteins) cause flagella to ROTATE, not whip like in eukaryotes.
The very different structures of the prokaryotic and eukaryotic flagella is a clear example of…
Is this bacterium gram + or gram -?
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactMotility of Prokaryotes
Taxis
Taxis = to move towards or away from a stimulus
Chemotaxis – towards (positive) or away (negative) from a chemical.
Phototaxis – towards (positive) or away (negative) from light.
Bacterium exhibiting positive chemotaxis
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactInternal and Genomic Organization - membranes
Membrane organization reminiscent of mitochondria and chloroplasts
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Single circular chromosome in nucleoid region plus plasmids
Internal and Genomic Organization - membranes
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactReproduction and Adaptation in Prokaryotes
- Binary fission (asexual) every 1 to 3 hours (some only 20 min)
- ENDOSPORES
- Formed by certain bacteria when environment goes south (lacking a nutrient, etc…)
- Highly Resistant cells
- Bacterium replicates chromosome and surrounds with tough wall.
- Remainder of cell breaks down- Most endospores survive boiling and can persist dormant for 100’s of years
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotic Nutritional Classes
- There are prokaryotes in every nutritional class:
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotic Metabolic Relationships to O2
Obligate (strict) aerobes
Facultative aerobes
Obligate (strict) anaerobes
- Use oxygen for cell resp. CANNOT be without it
- Use O2 if present, switch to fermentation in absence of O2
- Poisoned by O2
- Two types:
1. Fermentation – bacteria that only do fermentation
2. Anaerobic respiration – use substance other than O2 as final electron acceptor like nitrate (NO3-) and sulfate (SO42-)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Nitrogen Fixation
N2 NH4+
Nitrogen fixing bacteria take atmospheric nitrogen (N2) and can convert it to NH4 (ammonium) for use in its amino acids and nitrogenous bases. Excess is secreted and used by plants as shown to the right…
Nitrogen Metabolic
THIS IS THE ONLY WAY NITROGEN CAN ENTER THE ECOSYSTEM…THIS IS WHERE ALL YOUR NITROGEN COMES FROM!!
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotic Metabolic Cooperation
Colonial Cooperation: Certain bacteria like the cyanobacterium Anabaena in colonies. Photosynthetic cells are mixed with heterocyst cells, which fix nitrogen only since O2 produced during photosyn. inhibits nitrogen-fixing enzymes.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Biofilms: Surface coatings of cooperating bacteria. Above, dental plaque, a biofilm that forms on tooth surfaces.
Channels form in the biofilm to allow nutrients and waste to enter and exit the interior of the film respectively.
Prokaryotic Metabolic Cooperation
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotic Phylogeny
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactComparing the three domains:
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Archaea Bacteria
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactArchaea Bacteria
Extremophiles - “lovers” of extreme conditions
1. Extreme Thermophiles
- thrive in hot environments
Ex. Sulfolobus – genus that live in sulfur-rich volcanic springs pushing 90°C.
2. Extreme Halophiles
- thrive in high salt environments
3. Methanogens- Obligate (strict) anaerobes – poisoned by O2
- Many species live in swamps and marshes
- Use CO2 to oxidize H2, releasing CH4 (methane) as waste.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Eubacteria
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactEubacteria
Fig 27.13 in book
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotic Symbiotic Relationships
Symbiosis
Hst – larger organismSymbiont – smaller organism
Mutualism (+/+)
Commensalism (+/0)
Parasitism (+/-)
Three Forms:
Human Intestinal bacteria
Glowing below eye of flashlight fish is organ containing bioluminescent bacteria. Light used to attract predators and mates. Bacteria gets nutrients from fish.
– relationship b/w organisms of different species in direct contact
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPathogenic (parasitic) Prokaryotes
- Cause about half of all human diseases**2 to 3 million die a year from lung disease caused by Mycobacterium tuberculosis
**2 million others die of diarrheal disease caused by prokaryotes
Lyme disease- Most widespread pest-carried disease in United States
- Tick carries spirochete Borrelia burgodorfi
- The tick is called a vector because it transmits the disease as would a mosquito that transmits the protist that causes malaria.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPathogenic (parasitic) Prokaryotes
- Cause about half of all human diseases**2 to 3 million die a year from lung disease caused by Mycobacterium tuberculosis
**2 million others die of diarrheal disease caused by prokaryotes
Lyme disease- Most widespread pest-carried disease in United States
- Tick carries spirochete Borrelia burgodorfi
- The tick is called a vector because it transmits the disease as would a mosquito that transmits the protist that causes malaria.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPathogenic Prokaryotes
ExotoxinsToxic proteins secreted by pathogenic bacteria
Ex. Cholera
- Life threatening diarrhea
- Caused by Vibrio cholera
Exotoxin called cholera toxin (CTX) causes intestinal cells to secrete Cl- into gut and water follows by osmosis
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPathogenic Prokaryotes
Endotoxins-Toxic lipopolysaccharides (glycosylated phosopholipids) found in outer membrane of Gram negative bacteria.
- Released when cell dies and outer membrane breaks down
Ex. All members of genus Salmonella- Typhoid fever (fecal oral route)
- Food poisoning (esp chicken)
Typhoid bacillus(Salmonella enterica)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProkaryotes in Research, Technology and Society
- Convert milk to cheese / yogurt
- E. coli in gene cloning
- Agrobacterium tumefaciens to make transgenic plants
- BioremediationUse of organisms to remove pollutants from the environment
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactProtists (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
C. mixotrophs – combine photosyn with hetertrophic nutrition
A. photoautotrophsB. heterotrophs
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Broken into three general categories based on ecological context:
1. Photosynthetic (plant-like) protists
3. Absorptive (fungus-like) protists
- algae
2. Ingestive (animal-like) protists
- protozoans
Protists
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
How did such incredible diversity arise?
Protists
Many species resulted from two rounds of endosymbiosis…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Phylogenetic tree showing the major clades of protists.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
A complete branch of a phylogenetic tree. Above how many clades are highlighted?
What’s a clade?
Two, the blue and the red because these are complete branches. The green is not complete.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Euglenozoa Fig. 28.8
Characterized by spiral or crystalline rod within flagella in addition to 9+2 arrangement of microtubules.
Cyrstalline structure has unknown function.
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Euglenozoa Fig. 28.8
Phylum kinetoplastid
- Causes sleeping sickness
- Spread by African tsetse fly- Fatal if untreated
Ex. Genus Trypanosoma
- Evade immune system by repeatedly changing the proteins on the surface of the cell
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Euglenozoa Fig. 28.8
Phylum euglenid
- Found in freshwater
- Photoautotroph if sunlight available otherwise heterotroph by absorbing nutrients from environment (mixotroph)
Ex. Euglena
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Alveolata Fig. 28.8
Characterized by sacs below membrane called alveoli having yet unknown function
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum dinoflagellates
- Abundant as both marine and freshwater phytoplankton
- Bloom (explosion of growth) can cause “red tide”
Kingdom Alveolata
Phytoplankton – phyto = photosynthetic, plankton = “free-drifting”
- free-drifting photosynthetic organisms (cyanobacteria is also a large part of phytoplankton)
- Secrete toxins that bioaccumulate in molluscs making them dangerous to eat
- Have internal “plates” of cellulose giving its characteristic shape…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Ciliates
- Obviously use cilia to move and feed
- Can have more than one of each
Kingdom Alveolata
Two types of nuclei
- Large (macro) nucleus
- Smaller (micro) nucleus
Ex) Paramecium
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Ciliates
- Arranged in small units each having many duplicates of a single gene
Kingdom Alveolata
Macronucleus
- Contains dozens of copies of genome
- Genes are not on chromosomes (they don’t have chromosome)
- The gene products (i.e. proteins) control daily functions like feeding, waste removal, etc…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Ciliates
- Food vacuoles fuse with lysosomes
Kingdom Alveolata
Feeding
- Mainly on bacteria, which are moved through oral groove and phagocytosed at “cell mouth” into food vacuoles.
- Undigestable material is egested when lysosomes fuse with cell membrane
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Ciliates
Conjugation
Kingdom Alveolata
Reproduction
- Mostly asexually by “binary fission”
- two organisms exchange haploid micronuclei (see fig 28.12b above and use book for more detail)
- Genetic diversity, NOT REPRODUCTION
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Diatom (Bacillariophytes)
Kingdom Stramenopila
- Unicellular Algae
- Protection from predators
- glass-like silica based cell wall as shown in figure
- Withstand pressures up to 1.4 million kg/m2 (pressure applied by the leg of a table with an elephant standing upon it)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Diatom (Bacillariophytes)
Kingdom Stramenopila
Reproduction
- Sexual reproduction is not common, but does occur
- Usually asexually by mitosis
- Estimated 100,000 species
Diversity
- Major component of phytoplankton in oceans and lakes
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Golden Algae (chrysophytes)
Kingdom Stramenopila
(chrysos = golden)
- Freshwater and marine plankton
- Contain yellow/brown cartenoid pigments
- All obviously photosynthetic, some species mixotrophs
- Most unicellular, but some, as shown, are colonial
Dinobryon
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Brown Algae (phaeophytes – guess what phaeo means…)
Kingdom Stramenopila
- All are multicellular and most are marine (salt water – ocean)
- Largest and most complex algae (its what you call seaweed)
- Common along temperate costs like ours
Kelp
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact
Phylum Brown Algae
Kingdom Stramenopila
- The body of the seaweed that is plant-like
Thallus Kelp
- Basically, the holdfast, stipe (stem-like) and blades (leaf-like) (see above)
- root-like structure at base solely for anchoring, not absorption like roots of plants
Holdfast
Sea palm (Postelsia)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylum Brown Algae
Kingdom Stramenopila
This is important to understand because as you might guess, since plants evolved from multicellular algae, they also do this.
Life-cycle: Alternation of Generations
- The two generations are structurally different as opposed to being isomorphic
Heteromorphic
Laminaria (a brown algae)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom 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
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Cercozoans and Radiolarians
Foraminiferans (Forams) Radiolarian
- Named for porous shells called tests
- Foramen means “little hole”
- Organic molecules hardened with CaCO3
- Pseudopodia extend through pores of shell and fx in test formation, swimming and feeding
- Pseudopodia called axopodia
- Tests made of silica
Both of these phyla consist of amoebas because…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Amoebozoans
- Amoeba with lobe shaped rather than threadlike pseudopods belong to this clade:
Now this amoeba belongs to the above kingdom…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Amoebozoans
Phyla: Gymnamoeba
Phagocytosis of a ciliate:
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Two major types:
Were once thought to be fungus hence the name, but molecular evidence has revealed convergent evolution
1. Plasmodial Slime Molds
2. Cellular Slime Molds
They in part by their life cycles…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Plasmodial Slime Mold Life Cycle
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Amoebozoans
Phyla: Slime Molds (mycetozoans)
Cellular Slime Mold Life Cycle
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactPhylogeny of protists Fig. 28.4
Let’s examine a handful of these clades…
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom 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
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom 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
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
- Chlorophytes and Charophyceans
*Charophyceans and most related to land plants and are discussed at beginning of Ch. 29 with plants
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom 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)
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impactKingdom Chlorophyta
Chloro = green
Green Algae
Complicated life cycle of asexual and sexual stages:
Syngamy = fusion of gametes, aka fertilization/conception
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Chapter 27: Prokaryotes - structure, function, diversity, evolution, impact