9/24/2013. Bacteria and Archaea. Masters of Adaptation. Archaea. Three domain system: The present tree of life

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Chapter 27 Masters of Adaptation Structural and functional adaptations contribute

27.17-a Archaea Subgroup: Alpha Proteobacteria Subgroup: Beta Proteobacteria

Thermophilus aquaticus Methanogens Gamma Proteo- Delta bacteria Epsilon Subgroup:

Subgroup: Delta Proteobacteria Nitrosomonas (colorized TEM) Subgroup: Epsilon

1 200 m m 2 m 1 m Bacteria and Archaea Three domain system: The present tree of life Chapter 27 Masters of Adaptation Structural and functional adaptations contribute to prokaryotic success Unicellular Small Variety of shapes Well organized Figure a Archaea Subgroup: Alpha Proteobacteria Subgroup: Beta Proteobacteria Alpha Beta Extremophiles Extreme halophiles Halobacterium Extreme thermophiles Thermophilus aquaticus Methanogens Gamma Proteo- Delta bacteria Epsilon Subgroup: Gamma Proteobacteria Rhizobium (arrows) inside a root cell of a legume (TEM) Subgroup: Delta Proteobacteria Nitrosomonas (colorized TEM) Subgroup: Epsilon Proteobacteria Thiomargarita namibiensis containing sulfur wastes (LM) Fruiting bodies of Chondromyces crocatus, a myxobacterium (SEM) Helicobacter pylori (colorized TEM) 1

(colorized TEM) Cyanobacteria Leptospira, a spirochete (colorized TEM) Gram-Positive Bacteria (a) Gram-positive bacteria: peptidoglycan traps crystal violet.

Gram-positive bacteria Gram-negative bacteria Carbohydrate portion of lipopolysaccharide Oscillatoria, a filamentous cyanobacterium Streptomyces, the source of many antibiotics (SEM) Hundreds of

include Actinomycetes, which decompose soil Bacillus anthracis, the cause of anthrax Clostridium botulinum, the cause of botulism Some Staphylococcus and Streptococcus, which can be pathogenic

2 2. 40 m 2 m 2 m Figure b Chlamydias Spirochetes Cell-Surface Structures Cell wall Bacteria have peptidoglycan Archaea have polysaccharides and proteins but lack peptidoglycan Chlamydia (arrows) inside an animal cell (colorized TEM) Cyanobacteria Leptospira, a spirochete (colorized TEM) Gram-Positive Bacteria (a) Gram-positive bacteria: peptidoglycan traps crystal violet. (b) Gram-negative bacteria: crystal violet is easily rinsed away, revealing red dye. Gram-positive bacteria Gram-negative bacteria Carbohydrate portion of lipopolysaccharide Oscillatoria, a filamentous cyanobacterium Streptomyces, the source of many antibiotics (SEM) Hundreds of mycoplasmas covering a human fibroblast cell (colorized SEM) Peptido- Cell glycan wall layer Plasma membrane 10 m Outer membrane Cell Peptidowall glycan layer Plasma membrane Gram-positive bacteria include Actinomycetes, which decompose soil Bacillus anthracis, the cause of anthrax Clostridium botulinum, the cause of botulism Some Staphylococcus and Streptococcus, which can be pathogenic Mycoplasms, the smallest known cells Gram-Positive Bacteria Gram-Positive Bacteria Capsule Slime layer Fimbriae Pili Cell surface structures Streptomyces, the source of many antibiotics (SEM) Hundreds of mycoplasmas covering a human fibroblast cell (colorized SEM) Motility Internal Organization and DNA Taxis Chemotaxis Flagella Formed from from secretory protein system Cell wall Flagellum Hook Motor Filament 20 nm Lack compartmentalization Specialized membranes perform metabolic functions DNA packaged in a circular chromosome in the nucleoid region Additional rings of DNA called plasmids 0.2 m 1 m Chromosome Plasmids Plasma membrane Rod Peptidoglycan layer Respiratory membrane Thylakoid membranes 1 m 2

Key features: Reproduction and Adaptation They are small, reproduce by binary fission, and have short generation times Many prokaryotes form metabolically inactive endospores, which can remain viable

Three factors contribute to genetic diversity: Rapid reproduction Mutation Genetic recombination 0.

3 Key features: Reproduction and Adaptation They are small, reproduce by binary fission, and have short generation times Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries Coat Endospore Prokaryotes have considerable genetic variation: why? Three factors contribute to genetic diversity: Rapid reproduction Mutation Genetic recombination 0.3 m Transformation and Transduction Transformation: incorporating foreign DNA from the surrounding environment Transduction: movement of genes between bacteria by bacteriophages (viruses that infect bacteria) Recombination A Phage A B A B A B A Donor cell Recipient cell Conjugation and Plasmids Conjugation: process where genetic material is transferred between prokaryotic cells F (fertility) factor is required for the production of pili Sex pilus 1 m A B Recombinant cell Diverse nutritional and metabolic adaptations have evolved in prokaryotes Phototrophs obtain energy from light Chemotrophs obtain energy from chemicals Autotrophs require CO 2 as a carbon source Heterotrophs require an organic nutrient to make organic compounds The Role of Oxygen in Metabolism Obligate aerobes require O 2 for cellular respiration Obligate anaerobes are poisoned by O 2 and use fermentation or anaerobic respiration Facultative anaerobes can survive with or without O 2 3

Uptake of K by plants (mg) Nitrogen Metabolism Nitrogen is essential for the production of amino acids and nucleic acids Prokaryotes can metabolize nitrogen in a variety of ways In nitrogen fixation,

2 Prokaryotes play crucial roles in the biosphere Chemical Recycling Chemoheterotrophic prokaryotes function as decomposers Availability of nitrogen, phosphorus, and potassium for plant growth 1.0 0.

4 Uptake of K by plants (mg) Nitrogen Metabolism Nitrogen is essential for the production of amino acids and nucleic acids Prokaryotes can metabolize nitrogen in a variety of ways In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N 2 ) to ammonia (NH 3 ) Table 27.2 Prokaryotes play crucial roles in the biosphere Chemical Recycling Chemoheterotrophic prokaryotes function as decomposers Availability of nitrogen, phosphorus, and potassium for plant growth No bacteria Strain 1 Strain 2 Soil treatment Strain 3 Seedlings growing in the lab Ecological Interactions Symbiosis larger host and smaller symbiont Mutualism Commensalism Parasitism Prokaryotes have both beneficial and harmful impacts on humans Mutualistic Bacteria Human intestines are home to about 500 1,000 species of bacteria Pathogenic Bacteria Lyme disease is caused by a bacterium and carried by ticks Pathogenic prokaryotes typically cause disease by releasing toxins Exotoxins are secreted and cause disease even if the prokaryotes that produce them are not present Endotoxins are released only when bacteria die Toxic protein crystals from Bacillus thuringiensis Bt 4

Protists Chapter 28 Most eukaryotes are single-celled organisms Protists are eukaryotes Eukaryotic cells have organelles and are more complex than prokaryotic cells Most protists are unicellular, but

5 Protists Chapter 28 Most eukaryotes are single-celled organisms Protists are eukaryotes Eukaryotic cells have organelles and are more complex than prokaryotic cells Most protists are unicellular, but there are some colonial and multicellular species Structural and Functional Diversity in Protists Protists exhibit more structural and functional diversity than any other group of eukaryotes Single-celled protists can be very complex, as all biological functions are carried out by organelles in each individual cell Protists, the most nutritionally diverse of all eukaryotes, include: Photoautotrophs which contain chloroplasts Heterotrophs absorb organic molecules or ingest larger food particles Mixotrophs Figure 28.2 Endosymbiosis Endosymbiosis is the process in which a unicellular organism engulfs another cell Mitochondria aerobic prokaryote Plastids photosynthetic cyanobacterium The plastid-bearing lineage of protists evolved into red and green algae Membranes are represented as dark lines in the cell. Cyanobacterium Primary endosymbiosis Heterotrophic eukaryote One of these membranes was lost in red and green algal descendants. Red alga Secondary endosymbiosis Secondary endosymbiosis Secondary endosymbiosis Plastid Dinoflagellates Apicomplexans Stramenopiles Plastid Euglenids Green alga Chlorarachniophytes 5

Five Supergroups of Eukaryotes Excavata Chromalveolata Rhizaria Archaeplastida Unikonta Polyphyletic

anaerobic environments Diplomonads Giardia intestinalis, a diplomonad parasite Parabasalids Trichomonas

photosynthetic autotrophs, and parasites A spiral or crystalline rod of unknown function inside their

6 Five Supergroups of Eukaryotes Excavata Chromalveolata Rhizaria Archaeplastida Unikonta Polyphyletic Group Excavates modified mitochondria unique flagella Diplomonads Lack plastids and most live in anaerobic environments Diplomonads Giardia intestinalis, a diplomonad parasite Parabasalids Trichomonas vaginalis, a sexually transmitted disease Flagella Euglenozoans Includes predatory heterotrophs, photosynthetic autotrophs, and parasites A spiral or crystalline rod of unknown function inside their flagella Flagella 0.2 m Undulating membrane 8 m Crystalline rod (cross section) Ring of microtubules (cross section) 6

7 3 m 0.2 m Chromalveolates may have originated by secondary endosymbiosis The proposed endosymbiont is a red alga Includes the alveolates and the stramenopiles Alveolates Members of the clade Alveolata have membrane-bounded sacs (alveoli) just under the plasma membrane The alveolates include Dinoflagellates Apicomplexans Ciliates Flagellum Alveoli Dinoflagellates Have two flagella and each cell is reinforced by cellulose plates They are a diverse group of aquatic phototrophs, mixotrophs, and heterotrophs Toxic red tides are caused by dinoflagellate blooms Flagella Apicomplexans Parasites of animals Most have sexual and asexual stages that require two or more different host species for completion Plasmodium requires both mosquitoes and humans to complete its life cycle Ciliates Use of cilia to move and feed Large macronuclei and small micronuclei Genetic variation results from conjugation, in which two individuals exchange haploid micronuclei Paramecium 50 m 7

40 m Stramenopiles Important phototrophs as well as several clades of heterotrophs Most have a hairy flagellum paired with a smooth flagellum Stramenopiles include diatoms, golden algae, brown algae,

diatom walls compose much of the sediments known as diatomaceous earth This removes carbon dioxide from the atmosphere and pumps it to the ocean floor Golden Algae Golden algae are named for their

Algae Largest and most complex algae All are multicellular, and most are marine Brown algae include many species commonly called seaweeds Alternation of Generations A variety of life cycles have

8 40 m Stramenopiles Important phototrophs as well as several clades of heterotrophs Most have a hairy flagellum paired with a smooth flagellum Stramenopiles include diatoms, golden algae, brown algae, and oomycetes Smooth flagellum Hairy flagellum Diatoms unicellular algae with a unique two-part, glass-like wall of hydrated silica major component of phytoplankton and are highly diverse Fossilized diatom walls compose much of the sediments known as diatomaceous earth This removes carbon dioxide from the atmosphere and pumps it to the ocean floor Golden Algae Golden algae are named for their color, which results from their yellow and brown carotenoids The cells of golden algae are typically biflagellated, with both flagella near one end Most are unicellular, but some are colonial Brown Algae Largest and most complex algae All are multicellular, and most are marine Brown algae include many species commonly called seaweeds Alternation of Generations A variety of life cycles have evolved among the multicellular algae The most complex life cycles include an alternation of generations, the alternation of multicellular haploid and diploid forms Heteromorphic generations are structurally different, while isomorphic generations look similar 8

Alternation of generations Oomycetes water molds, white rusts, and downy mildews once considered fungi based on morphological studies Most are decomposers or parasites They have filaments (hyphae)

9 Alternation of generations Oomycetes water molds, white rusts, and downy mildews once considered fungi based on morphological studies Most are decomposers or parasites They have filaments (hyphae) that facilitate nutrient uptake Their ecological impact can be great, as in potato blight caused by Phytophthora infestans Rhizarians are a diverse group of protists defined by DNA similarities DNA evidence supports Rhizaria as a monophyletic clade Amoebas move and feed by pseudopodia; some but not all belong to the clade Rhizaria Rhizarians include radiolarians, forams, and cercozoans Radiolarians Marine protists called radiolarians have tests fused into one delicate piece, usually made of silica Radiolarians use their pseudopodia to engulf microorganisms through phagocytosis The pseudopodia of radiolarians radiate from the central body Pseudopodia 200 m Foraminiferans or Forams Porous, generally multichambered shells, called tests Pseudopodia extend through the pores in the test Foram tests in marine sediments form an extensive fossil record Many forams have endosymbiotic algae Cercozoans Include most amoeboid and flagellated protists with threadlike pseudopodia They are common in marine, freshwater, and soil ecosystems Most are heterotrophs, including parasites and predators Chromatophore 9

Bonnemaisonia hamifera Red algae and green algae are the closest relatives of land plants Red Algae 20 cm Over a billion years ago, a heterotrophic protist acquired a cyanobacterial endosymbiont The

10 Bonnemaisonia hamifera Red algae and green algae are the closest relatives of land plants Red Algae 20 cm Over a billion years ago, a heterotrophic protist acquired a cyanobacterial endosymbiont The photosynthetic descendants of this ancient protist evolved into red algae and green algae Land plants are descended from the green algae Reddish in color due to an accessory pigment called phycoerythrin Red algae are usually multicellular; the largest are seaweeds Red algae are the most abundant large algae in coastal waters of the tropics Nori 8 mm Dulse (Palmaria palmata) Green Algae Green algae are a paraphyletic group The two main groups are chlorophytes and charophyceans Charophytes are most closely related to land plants Most chlorophytes live in fresh water, although many are marine Other chlorophytes live in damp soil, as symbionts in lichens, or in snow Unikonts include protists that are closely related to fungi and animals Includes animals, fungi, and some protists This group includes amoebozoans and the opisthokonts (animals, fungi, and related protists) Amoebozoans amoeba that have lobe- or tube-shaped, rather than threadlike, pseudopodia They include slime molds, gymnamoebas, and entamoebas Plasmodial Slime Molds Many species of plasmodial slime molds are brightly pigmented, usually yellow or orange At one point in the life cycle, plasmodial slime molds form a mass called a plasmodium that is not multicellular but has many diploid nuclei 1 mm 4 cm 10

10 m Cellular Slime Molds Form multicellular aggregates in which cells are separated by their membranes Cells feed individually, but can aggregate to form a fruiting body Dictyostelium discoideum is

11 10 m Cellular Slime Molds Form multicellular aggregates in which cells are separated by their membranes Cells feed individually, but can aggregate to form a fruiting body Dictyostelium discoideum is an experimental model for studying the evolution of multicellularity Gymnamoebas Gymnamoebas are common unicellular amoebozoans in soil as well as freshwater and marine environments Most gymnamoebas are heterotrophic and actively seek and consume bacteria and other protists Entamoebas Entamoebas are parasites of vertebrates and some invertebrates Entamoeba histolytica causes amebic dysentery, the thirdleading cause of human death due to eukaryotic parasites 200 m Opisthokonts Include animals, fungi, and several groups of protists Protists play key roles in ecological communities Protists are found in diverse aquatic environments Protists often play the role of symbiont or producer Symbiotic Protists Some protist symbionts benefit their hosts Dinoflagellates nourish coral polyps that build reefs Wood-digesting protists digest cellulose in the gut of termites Some protists are parasitic Plasmodium causes malaria Pfiesteria shumwayae is a dinoflagellate that causes fish kills Phytophthora ramorum causes sudden oak death 11

photosynthetic protists are limited by nutrients These populations can explode when limiting nutrients are

12 Photosynthetic Protists Many protists are important producers that obtain energy from the sun In aquatic environments, photosynthetic protists and prokaryotes are the main producers In aquatic environments, photosynthetic protists are limited by nutrients These populations can explode when limiting nutrients are added Important in food webs Other consumers Herbivorous plankton Carnivorous plankton Prokaryotic producers Protistan producers 12

Protists 9/11/2017. Endosymbiosis

Protists 9/11/2017. Endosymbiosis Protists Chapter 28 Most eukaryotes are single-celled organisms Protists are eukaryotes Eukaryotic cells have organelles and are more complex than prokaryotic cells Most protists are unicellular, but there