Transcript Domain Eukarya: Protista

Domain Eukarya:
Protista
Domain Eukarya
 Every living thing on Earth, except for bacteria and archaea
 More complex organization
 Have a nucleus
 Have membrane-bound organelles
 Mitochondria, endoplasmic reticulum, Golgi bodies, etc.
 4 kingdoms
 Animalia
 Plantae
 Fungi
 Protista
Kingdom Protista
 The protists
 Depending on who you ask ~10-20 phyla of protists exist
 Single-celled and multicellular organism
 Can be:
 plant-like,
 animal-like, or
 fungi-like
Protista Reproduction
 Can reproduce sexually and asexually
 Many of the unicellular protists reproduce asexually (much like bacteria)
 Have a method for exchanging genetic material (called conjugation)
 They attach and exchange small pieces of DNA
 Most protists reproduce sexually
Classification and Evolution of Protists
 “Trash-can” kingdom
 If it is not a plant, animal, or fungus, it is a protest
 Very hard to classify because there is such a diversity
 Will likely be broken into several new kingdoms in the future
 Scientists usually break them down into animal-like, plant-like, and fungi-like based on their
traits
 Were the first eukaryotes to evolve
 Because they are small, they have not left a lot of fossils (only a few types have
been found)
 Comparing genetic evidence, they likely evolved early from single-celled organisms
(prokaryotes) who had acquired structures that worked similar to organelles
 Example: Prokaryotes “eat” by engulfing particles and bringing them into their membrane.
Endosymbiotic Theory
 Endo=Inside (Think “enter”)
 Symbiosis=2 organisms of different species working together
 Endosymbiotic Theory=Organelles were once separate, but were “eaten” and formed
mutualistic relationships
 Eventually became parts of the cell
 Helped organism to make energy (chloroplasts and mitochondria)
 Evidence:
 Mitochondria in eukaryotic organisms have different DNA from the organisms who have them
(called Mitochondiral DNA)
 This DNA shows more closely related genetic relationship to bacteria than to eukaryotes
 Chloroplasts in eukaryotic organisms also have different DNA than the plants and protists that
contain chloroplasts
 This DNA can be traced directly to photosynthetic bacteria
Plant-Like Protists
 Called algae
 Algae are not plants! They are protists.
 Contain chloroplasts
 Producers-able to make their own food
 Many also have cell walls, similar to plants
 Many types of algae exist
 Classified on whether they are unicellular or multicellular
 Unicellular: Diatoms, Dinoflagellates, euglenoids
Diatoms
 Small, unicellular algae.
 Exist in large populations
 Form beautiful structures as colonies (picture)
 Cell wall is made of silica (pretty much glass)
 https://www.youtube.com/watch?v=JYB5529hDPI
Dinoflagellates
 Have 2 flagella
 They spin as they move
 Bioluminescence
 https://www.youtube.com/watch?v=uqJbUKEPgXc
Euglenoids
 Have characteristics of both plants and animals.
 Many have chloroplasts, some do not
 Some have the ability to make their own food when there is light, and must eat other
organisms when there is no light
 Found in most aquatic environments
 You would find them in Fulda Lake
 Have a photosensitive “eyespot” that helps them move toward light
 No cell wall
 Can use their cell membrane as a way to move
 Also have flagella that helps propel them in liquid
 https://www.youtube.com/watch?v=fI7nEWUjk3A
Red Algae
 Multicellular
 Sometimes called “seaweed”
 Have chlorophyll for photosynthesis
 They are red due to a red pigment
 Live deeper than brown and green algae
 Up to 200 m deep
Green Algae
 Multicellular or unicellular
 “Seaweed”
 Large amounts of chlorophyll
 Most plant-like of all algae
 Thought to be the ancestor of all plants
 Most live in the water, but some live outside the water
Brown Algae
 Multicellular
 Called “Kelp”
 Located between areas where green and red algae grow
 Usually in cooler, salty water
 Typically grow in “forests”-dense areas
 Contain chlorophyll and a brown pigment
 They are an important food source, for fish and humans
 Can grow up to 100m (328 feet) long
Algae Benefits and Issues
 Algae is an important producer in aquatic food webs
 Especially diatoms and dinoflagellates
 Algal blooms
 Can bloom out of control and be toxic for other organisms (even humans)
 Usually the result of dinoflagellates
 Product uses
 Carrageenan (from certain algae) is used in toothpaste, salad dressing, and pudding to give it
a creamy texture
 Ice cream and marshmallows use algin from brown algae to make them thick
 Algin
 Diatoms are used (because of their glass-like cell walls) in insulation and road paint (the stuff
that shines at night)
Animal-like Protists
 Also known as protozoans
 Live in or on dead organisms that are found in water
 Usually classified based on how they move
 Ciliates
 Protozoans that have cilia (hair-like structures on outside of cell) that help them swim
 Flagellates
 Have flagella that help them move
 Pseudopods (“false feet”)
 Part of the cell extends and pulls them along
 Others
 Some cannot move and must instead get nutrients from other organisms
 Parasites
Importance of Protozoans
 Food source for organisms
 Help build up sediment
 Symbiotic relationships
 Termites have protozoans in their gut that help them break down wood
Dark Side of Protozoans
 Some protozoans can cause disease
 Typically, they have a very complicated life cycle
 Often have an intermediate host that they must infect before getting to humans
Plasmodium malariae
 Protozoans of the genus Plasmodium cause malaria
 Begins when a person is bitten by a mosquito carrying undeveloped Plasmodium protozoans
 In the human, they develop and begin reproducing in red blood cells
 When the offspring grow, they cause the RBC to burst, releasing them to reproduce in other RBCs
 Another mosquito bites the human and picks up red blood cells containing the offspring
 They then bite another human, transmitting the disease
 The cycle repeats
 Symptoms of malaria
 Vomiting, fever, tiredness, severe headache
 Prognosis
 With treatment, recovery is possible
 However, it can kill hours after infection, before treatment is possible
 In 2013, there were nearly 200 million people infected with malaria
 584,000 died
 https://www.youtube.com/watch?v=qvlTOhCmxvY
African Trypanosomiasis (African sleeping
sickness)
 Protozoan: Trypanosoma bruceli
 Intermediate Host: Tsetse fly
 Primary Host: Humans
 Symptoms: Itching and headaches at first. Months later, heart and kidney
dysfunction, brain infection, disrupted sleep patterns, and brain damage.
Fatal if not treated.
Toxoplasmosis
 Protozoan: Toxoplasmosis gondii
 Intermediate Host: Mice, birds
 Primary Host: Cats
 Unintended Host: Humans
 Symptoms: Most show no symptoms. However, brain inflammation and changes in
behavior result.
 In mice, the protozoan results in the mouse becoming attracted to cat urine
 This results in the mouse being eaten by the cat
 Humans become affected by cleaning cat’s litter boxes
 Can be fatal in humans, but not commonly
 Pregnant women risk passing it on to the fetus, and the fetus can become seriously infected.
 “Crazy cat lady syndrome”
Fungus-Like Protists
 Protists that were once considered to be fungi
 Produce spores, similar to fungi, for reproduction
 All are consumers
 Most can move using pseudopods
Slime Molds
 “Dog vomit mold” or “scrambled egg mold”
 Protists that form delicate, web-like structures on their food source
 Mostly found on decaying logs or wood
 Can feed on any dead or decaying organism
 Decomposers or consumers
 Sometimes both
Water Molds and Downy Mildews
 Grow like mold on plants and animals
 Some are parasitic
 Water molds can kill fish
 Downy mildew can kill plants
 Most are decomposers
 Have cell walls closely resembling plants
 Produce spores like fungi
 Can have negative economic effects
 Water mold can spread quickly and kill a lot of fish
 Downy mildew has, in the past, nearly wiped out crops
 Also caused the Irish Potato Famine
 Killed over 1 million people through starvation