Lecture 20 Flashcards

1
Q

What are coccolithophorids (Haptophyta)?

A

••Diverse protistan pirates that took up a red algal chloroplast and have Chl A and C. ••A few species dominate open oceans and account for 10-15% of world’’s carbon fixation and 20% of the oxygen we breath. ••Cells are mixotrophic with a complex mechanism of prey capture. -accessory pigments= make them look golden brown -taking out carbon out of the atmosphere= the exoskeletons don’t get recycled for 100 000s of years -world’s greatest producers

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2
Q

What are the most important animal-like consumers in the Protista kingdom?

A

cilliates

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3
Q

What are features of cilliates?

A

• Unicellular • Diverse and complex • Covered with flagella called cilia (i.e., ciliates) • Two types of nuclei: Micronucleus and Macronucleus • Predatory - feed on bacteria, protists, other ciliates etc. • Example: Paramecium -cilia= same organisation as flagella -extremely complex for a unicellular organisms

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4
Q

Describe the structre of a cilliate:

A
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5
Q

What are the two nuclei in cilliates and their function?

A

-two nuclei, as they are so large and complex micronucleus= the typical, normal mitosis, macronucleus= where lot of the DNA transcribed= the housekeeping genes as the micro one couldn’t keep up- no precision needed in macronucleus as theere are 1000s of copies of each DNA bit so just pinched and separated into two

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6
Q

What are the cillia for in cilliates?

A

cilia= to move and accumulate food
-to set up current and bring in the food

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7
Q

What are choanoflagellates?

A
  • (‘collar’ flagellates or sponge-like protists)
  • • Aquatic habitats • Tiny, unicellular protists closely related to the choanocytes of sponges
  • At the base of the phylogenetic tree that gave rise to the animals
  • Heterotrophic consumers
  • carnivororus and as long as smaller than them they’ll eat it= so they often eat even their own
  • choanoflagellates= gave rise to animals
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8
Q

What are slime moulds (ameboid protists)?

A

-Slime Moulds - Amoeboid Protists

  • Heterotrophs - absorb or engulf food after external digestion (like fungi)
  • Major decomposers and recyclers
  • Reproduce by spores in fruiting bodies called sorocarps
  • Cellular slime moulds (Dictyostelids) - feed on bacteria
  • Acellular slime moulds (Myxomycetes) - decomposers
  • they break down food outside by enzymes and then ingest the nutristion= break down matter
  • dicytoselids= feed externally as well

fruiting bodies= colourful

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9
Q

What is the reprodzctive cycle of slime moulds (ameboid protists)?

A
  • no sex and no meiosis
  • amoebae= eat bacteria when food runs out= chemical pheromone present=need to reproduce= they come together = pseudoplasmodium and then what looks like slugs=(more slugs may join together if happen to meet)and then sets down and spores in a different place with more food= all individuals but cooperate to make these structures= how does it happen? the mechanism not clear
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10
Q

What are the oomycetes?

A
  • Superficially like true fungi, but related to diatoms and brown algae.
  • Zoospore infects plant tissue; hyphal filaments penetrate and parasitize cells.
  • Phytophthora infestans: late blight of potato.
  • Phytophthora cinnamomi: eucalypt dieback

-look like fungi, even in microscope look similar
phytopthora= irish famine

  • Fungal-like Absorbers and Recyclers
  • they used to have a chloroplasts but now live like parasites
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11
Q

How do you recognise oomycetes from fungi?

A

filament walls of cellulose, nuclei are diploid 2N
-oogonia and zoospores=
because of zoospore(gamete)= know they are not fungi
-the flagella on those are the same as in the kelps etc= different from fungi
-but look like fungi otherwise

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12
Q

How did some protists undergo change from producers to absorbers?

A
  • In protists that have lost the ability to photosynthesize, their chloroplasts have become reduced in size and limited in function.
  • Some of these organisms have been shown to be protistan pirates
  • Cells with reduced chloroplasts are often parasites, and many cause deadly diseases (e.g., malaria). We’re interested in the Apicomplexa.

-oomycetes= used to be red brown algae but for some reason lost chloroplast= life-style change

malaria= used to be protistan pirates red algae= used to photosynthesize

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13
Q

What are the apicomplexa?

A

-Endoparasites of animals (5000 species) such as Malaria and Toxoplasma

  • Named for their apical complex - used to penetrate host cells(apical complex- attach and penetrate into other cell= apicomplexa (name comes from there)
  • Why do botanists study Malaria? Reduced plastid called an apicoplast.

plasmodium= malaria also in apicomplexa

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14
Q

Why is malaria connected to apicomplexa?

A
  • plasmodium=Parasite eats contents of red cell and grows and divides into 24 daughters
  • Plant- like genes found in parasites –– within a previously unidentified compartment (apicoplast) in malaria parasite
  • Malaria chloroplast (apicoplast) has 4 bounding membranes

Results from secondary enodsymbiosis (4 membranes= used to be protistan pirate)

-the arrow= 2 sets of extra non nuclear genes, it has genes for chloroplasts

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15
Q

Why is herbicide possible treatement for malaria?

A

Can use herbicide: a compound that blocks chloroplast metabolism and in this case kills the parasite. due to the presence of the apicoplast taht has genes for a chloroplast

  • as the plastid plant dna= idea for killing malaria as it has the plastid
  • herbicides are very cheap to make (50 dollars a tonne)
  • some are safe and we know how they work
  • anti malarics= based on herbicides
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16
Q

The malaria parasite has a relict plastid: what does this mean for medical research?

A
  • We can treat the malaria parasite as a plant!
  • Plastid provides a specific target for drugs - a plant vs an animal target.
  • Herbicides attack plants via their plastids, and therefore don’t affect animals.

-• We’re determining the precise function of the malaria plastid and testing known inhibitors of these functions for anti-malarial activity

• Malaria remains one of the most devastating diseases of the world, with increasing resistance to drugs which often have toxic side-effects