Diversity Eukaryotic Microbes Final

8/8/2019 Diversity Eukaryotic Microbes Final

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Midterm results are graded, will beposted with key very soon

Average=56.6, top score=94, average of the top 6 scoreswas 89.3

We dont assign grades to individual midterms but IF thesame 6 students get the top scores overall, then cutoff forA = 90% of 89.3 =80.4B = 890% of 89.3 =71.5C = 70% of 89.3 =62.5D = 55% of 89.3 =49.1E below 49.1

If different students do well at different times (normallythe case), final cutoffs will be easier.

If you did really, really badly, when you pick up your exambooklet from Kaye Jays office, check that you bubbled theright version number.

Announcements

You must learn the material for the final exam

I encourage you to come to my office hours ifyou cant understand your mistakes

Also use the tutors for this, and to work outhow to study more effectively

I will not be here in the week or two beforethe final exam, so please seek help now.

Tuesday, Feb 21. Biological Evolution:What It Is and What It Isnt(Joanna Masel, EEB)

Tuesday, Mar 7. Cosmic Evolution:From Big Bang to Biology(Chris Impey, Astronomy)

Tuesday, Mar 21. Earth Evolution:The Formation of Our Planet(Joaquin Ruiz, COS Dean, Geosciences)

Tuesday, Mar 28. Social Evolution:Cooperation and Conflict FromMolecules to Society(Rick Michod, EEB)

Tuesday, Apr 11. Animal Evolution:Recycling Ancient Genes For New Uses(Lisa Nagy, MCB)

Tuesday, Apr 18. Human Evolution:Tracking Our Origins with DNA(Michael Hammer, ARL/EEB)

Tuesday, Apr 25. Disease Evolution:

The Example of HIV(Michael Worobey, EEB)

http://cos.arizona.edu/evolution/

Diversity ofEukaryotic Microbes

Where are microbes on tree of life?

Protists are eukaryotes that are not animals, plantsor fungi:

Yeast are unicellular fungi

Arch

aea

Bacteria

Eukaryote

s

Modified fromSimonson et al. (2005)PNAS 102, 6608-6613

Biology of protists

Most are unicellular, some are multicellular, afew are large

Some are heterotrophs, some are autotrophs,and some switch

Use membrane vesicles for many things Most reproduce both sexually and asexually

Protozoan and algae lump together manyphylogenetically distant protist groups


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Lots of endosymbiosis Lots of endosymbiosis

Evolutionary history of protists Diplomonads and Parabasalids

Giardia

Euglenozoans

Have flagella

2 clades

Euglenoids

Kinetoplastids

Euglenoids


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Various euglenoids collected fromstagnant ponds

Euglenoid Eutreptiamoves using flagella

Kinetoplastids parasitic

trypanosomes causesleeping sickness,leishmaniasis,Chagas disease,and East Coastfever

single largemitochondrion withkinetoplast housingmultiple, circularDNA molecules:edits own RNA

Alveolates

unicellular

cavities calledalveolijust belowtheir plasmamembranes

DinoflagellatesDistinctive appearance with two flagella

Dinoflagellates


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Dinoflagellates cause red tides When and why do dinoflagellatesbioluminesce?

Its like a burglar alarm against predators.

When a dinoflagellate is disturbed, it flashes. This attracts a secondary predator. The secondary predator is more likely to eat the

larger burglar than the smaller dinoflagellate. Often the threat alone is enough to scare off the

primary predator (burglar).

Breaking waves or stepping on sand also disturbdinoflagellates

Apicomplexans

Apical complex = mass of organelles at apicalend of spores

All are parasites: apical complex organelleshelp spore invade host tissue

Plasmodiumare the cause of malaria

Enters the human circulatory system by wayof the Anophelesmosquito

Extracellular parasite in the insect vector andan intracellular parasite in the human host

Life cycle of an apicomplexan

Liver

EVENTS IN MOSQUITO EVENTS IN HUMAN

Gametocytes

What part of the Plasmodiumlife cycledoes chloroquine interfere with?

erythrocytic stage

This treats the symptoms, butpersistent liver infection can leadto relapses

Ciliates have complex and variedbody forms with hairlike cilia

Almost allheterotrophic


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Large ciliate from termite gut movesusing thousands of synchronized flagella

Parameciumuses cilia to generatecurrent to carry prey to gullet

Ciliates have multiple nuclei

Cell life is run by products of macronucleus Micronuclei are involved in conjugation

Parameciumconjugation

Genetic recombination called conjugation Haploid micronuclei are exchanged

Fuse to form a new diploid micronucleus

Some protist body plans haveemerged multiple times

Amoebas

often live at the bottom of lakes, ponds etc.

Slime molds

Amoeba moves via pseudopods usingactin microfilaments

25xrealspeed

Thisamoebahaseatengreenalgae


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Chitin

Production of chitin is a shared derived traitfor

How fungi live

All use absorptive nutrition, secretingdigestive enzymes and absorbing thebreakdown products

Most are saprobes Earths main decomposers (with bacteria)

principal decomposers of cellulose & lignin

Some are parasites A few are mutualists

Saprobic fungi and bacteriaCell structure of multicellular fungi

Vegetative body= mycelium(plural mycelia)

Composed ofthreadlikehyphae(singular hypha)

Incomplete division into cells

Cell-likecompartmentsseparated bysepta (singular

septum)

Freemovement oforganelles,sometimeseven nuclei,and othermaterialscoenocytic hypha septate hypha

Fungus structure

Hyphae may

disperse to look for nutrients

clump together to exploit a food source


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Fungal hyphae attack a leaf

Hyphae give a large surface:volume ratio, which helpswith absorptive nutrition

Symbiotic fungiLichens are symbiotic associations of a fungus with a

Symbiotic fungi

The fungus obtains organiccompounds, while the plantis provided with water andsoil minerals

Some plants cant growwithout them

Fungalreproduction

Life cyclesdistinguish 4 phyla

When sex has notbeen observed,provisionallyclassified asimperfect fungi ordeuteromycetes:currently 25,000

species

Yeast are fungi

All four fungal phyla have unicellular species

Those of the Zygomycota, Ascomycota, andBasidiomycota are calledyeasts

The yeast Saccharomyces cerevisiaemakesCO2 and ethanol during fermentation

Used for bread and beer

Asexual reproduction via sporesProduction ofhaploid sporeswithin sporangia

Production of naked sporesat the tips of hyphae (notwithin sporangia) calledconidia


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Fungal spores are everywhere

Every breath we take is full of fungal spores

Most humans only succumb to fungalpathogens when immunocompromised

Plants are notso lucky

Parasitic fungus Ustilagomaydis(corn smut)

Neither wasthis ant

Spores of thisfungus dontgerminate untilingested by anant

More asexual reproduction

Cell division by unicellular fungi

Sexual reproduction

Some fungi have more than 2 mating types

Mating types dont look different

Mating can only occur between different matingtypes, preventing self-fertilization

Sexual reproduction when hyphae (or motile cellsin chytrids) of different mating types meet andfuse

Haplontic life cycle

Often diploid only very briefly as a zygote

Meiosis produces haploid nuclei again

Haploid spores divide mitotically to form haploidhyphae

This type of life cycle is called a haplontic lifecycle. Some protists have it too.


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Basidiomycete life cycle Life cycle of the basidiomyceteCortenellus shiitake

Other 3 phyla alsohave complex and

distinctive life cyclesChytrid

Zygotefungus

Ascomycete(sac fungus)

Important points about sex andreproduction

Sex = 2 nuclei fusing and undergoing meiosis Reproduction = one individual giving rise to

multiple: can be sexual or asexual Genetic recombination = any gene exchange: not

just sex, also nonreproductive processes such asconjugation

Dikaryotic individuals include 2 fused individuals,but not fused nuclei

Spores can be sexual or asexual, reproductive ornot: normally a small, tough cell with potential to

become new organism. Often capable of latency.Can be plant, bacterial, protist or fungal.

Spores are

a. produced only by bacteria.

b. produced only by eukaryotes.

c. always a product of sexual reproduction

d. often a way for an organism to lie dormantand wait for better times.

Documents

Diversity Eukaryotic Microbes Final