Eukaryotic microbes

Question 1

Protozoa

Answer 1

‘first animals’

• single cell eukaryotes
• lack a rigid cell wall, are generally motile and inhabit ‘wet’ environments
• are heterotrophs
• some species are parasites of animals or plants

Question 2

Algae

Answer 2

• essentially, protozoa that have a plastid

- those algae in which the plastid is a chloroplast are phototrophs

Question 3

protozoa as human parasites

Answer 3

Trypanosomes- african sleeping sickness
Leishmania- leishmaniasis (dumdum fever)
Entamoeba- amoebic dysentery

Question 4

phytophthora

Answer 4

P.infestants- potato blight

P.palmivora- affects cocoa pods

Question 5

Dinoflagellates

Answer 5

Causes red tides. Produce neurotoxins that can build up in fish, leading to paralytic neurotoxin, where when we eat it we suffered the effects. Can also remove all oxygen out of water and kill the fish
Probably began with a chloroplast from a red alga. 50% since discarded their chloroplast, others replaced this one from a green alga or haptophyte, other have temporary chloroplasts (kleptoplastids) obtained from their algal prey

Question 6

Diatoms

Answer 6

Eukaryotes in glass houses. Accumulate silica from the ocean. Dynamite- key ingredient is diatomaceous earth- blended with nitroglycerine to create a safe explosive

Question 7

Evolution of the eukaryotes

Answer 7

Believed to evolve from the prokaryotic Archaea, through a process of internal membrane formation, cell enlargement and serial endosymbiosis

Question 8

The alveolates

Answer 8

So called because the cells possess alveoli

Ciliates, Sporozoans, Dinoflagellates

Question 9

Ciliates

Answer 9

the most complex single celled organisms
found almost anywhere there is water
some/all of the cell surface is covered with cilia to propel through water or draw in food particles
feed on bacteria, algae or even other ciliates
ciliates in soils form cysts in order to survive long periods of drying

Question 10

Sporozoans

Answer 10

Haploid parasitic protozoa, habe complex life cycle usually involving growth stage within host cell
subgroup- apicomplexans- have distinctive structure at apical end of sporoazoite (involved in host cell invasion)

Question 11

Euglenoids

Answer 11

Flagellated protozoa including; Euglena, Trypanosomes, Leishmania

Question 12

Euglena

Answer 12

Many species of the genus possess chloroplasts, but are also capable of heterotrophic growth. In some species the chloroplast is easily lost
obtained their chlorplast in a separate green alga endosymbiosis in which the protozoan host was closely related to modern day trypansomes

Question 13

Trypanosomes

Answer 13

Flagellated pathogens of animals and plants. Life cycle involves an insect host. Possess a kinetoplast

Question 14

Oomycetes

Answer 14

so called “water moulds”. filamentous protozoa that may be free-living or parasitic. Many grow as ‘fungal-like’ hyphae and appear as rusts or mildews. originally considered to be fungi, now clear that they are related to the chromista

Question 15

Sarcodina

Answer 15

Largest phylum of protozoa. comprises the amoeba- unicellular protozoa that use pseudopodia for locomotion and feeding.
Most species free living, although some important parasites

Question 16

Entamoeba histolytica

Answer 16

A major human pathogen. two stages in life cycle: a) motile amoeba B) cyst
Ingested cysts are resistant to stomach acid and hatch to form amoebae in colon. New cysts form and pass through the bowel. Normally no symptoms, but in some individuals amebae becomes invasive and attacks organs, resulting localised infection or systemic infection including the brain

Question 17

Dictyostelium discoideum

Answer 17

A clever little amoeba
Haploid unicellular amoeba feeds on bacteria in soil and divide by mitosis. But when food source becomes scarce, then it undergoes a developmental change. Amoeboid movement exploited to create a multicellular organism. Cells secrete cAMP that attracts other cells. These adhere via glycoproteins expressed on cell surface. The slug then moves to new environment and differentiates. when mature, releases spores

Question 18

Evolution of algae

Answer 18

chloroplast arose from a cyanobacterium
free-living cyano was engulfed by a feeding amoeba
rather than being digested, the cyano became an endo-symbiont-providing fixed carbon and oxygen to its host in return for a safe, nutrient rich niche
over time, there was a transition for facultative symbiont to obligate symbiont to organelle

Question 19

3 lineages from primary endosymbiosis

Answer 19

chlorophyta (green algae)
rhodophyta (red algae)
Glaucocystophyta

Question 20

The different pigment compositions in lineages

Answer 20

Chlorophyta- chl.a and chl.B
Rhodophyta- Chl.a and phycoblinis
Glaucocystophyta- Chl.a and Phycobilins

Question 21

Glaucocystophyta

Answer 21

Relatively insignifcant group of freshwater algae

chloroplast retained peptidoglycan cell wall of the original Gram negative cyanobacterium

Question 22

secondary endosymbiosis

Answer 22

acquiring a second-hand chloroplast
A eukaryote within a eukaryotes 1) capture of a photosynthetic eukaryote 2) establishment of a symbiont 3) symbiont reduced to an organelle 4) Nucleomorph lost

Question 23

chlorarachiniophytes and cryptophytes

Answer 23

arose by separate endosymbiotic events involving a green and red alga
- the cells possess four genomes
a nuclear genome from the eukaryotic host
a nucleomorph genome from the eukaryotic alga
a chloroplast genome from a cyanobacterium
a mitochondrial genome from an alpha-proteobacterium

Question 24

remaining algal groups that acquired their chloroplast by secondary endosymbiosis involving red algae

Answer 24

The heterokonts
the haptophytes
Apicomplexa

Question 25

Apicomplexa

Answer 25

have retained a non-pigmented plastid with a reduced genome- various antibiotics target the bacterial RNA polymerase or ribosome are effective against some apicomplexan species

Question 26

sea slugs

Answer 26

another example of kleptoplastidy