Eukaryotic microbes

Question 1

What are protozoa?

Answer 1

Single cell eukaryotes. Lack a rigid cell wall, generally motile and inhabit wet environments, may form cysts or spores. Heterotrophs, some are parasites.

Question 2

What are algae?

Answer 2

Essentially protozoa with plastids. If plastid = chloroplast, algae are phototrophs.

Question 3

Protists =

Answer 3

Protozoa + Algae

Question 4

Cause of malaria

Answer 4

Plasmodium falciparum

Question 5

Causing of African sleeping sickness, transmitted by tse tse flies

Answer 5

Trypanosomes (T.Brucei)

Question 6

Causes dum dum fever

Answer 6

Leishmania

Question 7

Causes amoebic dysentery

Answer 7

Entamoeba hystolitica

Question 8

Causes potato blight

Answer 8

Phytophthora infestans

Question 9

Plant killers

Answer 9

Phytophthora

Question 10

Pathogen that affects cocoa pods

Answer 10

Phytophthora palmivora

Question 11

Cause red tides

Answer 11

Dinoflagellates

Question 12

Important for CO2 fixation, important in cycle of carbon

Answer 12

Emiliana huxleyi

Question 13

Have a cell wall made of silica

Answer 13

Diatoms

Question 14

3 processes involved in evolution of ek from pk Archae

Answer 14

• Internal membrane formation (invagination of pm)
• Cell enlargement
• Serial endosymbiosis

Question 15

Modern day bacterium with nuclear envelope

Answer 15

Gemmata obscuriglobis

Question 16

Modern day bacterium with internal membrane system

Answer 16

Cyanobacteria, thylakoid membranes

Question 17

4 majour groups of protozoa

Answer 17

Alveolates

Euglenoids

Oomycetes

Sarcodina

Question 18

3 main phyla of alveolates (protozoa)

Answer 18

Ciliates

Sporozoans

Dinoflagellates

Question 19

3 main phyla of euglenoids

Answer 19

Euglena

Trypanosomes

Leishmania

Question 20

Example of ciliate

Answer 20

Paramecium

Question 21

Examples of sporozoans

Answer 21

Apicomplexans: plasmodium falciparum, Toxoplasma, Eimeria

Question 22

Examples of oomycetes

Answer 22

P. infestans, Plasmopara viticola, Saprolegnia species

Question 23

What is the largest phylum of protozoa?

Answer 23

Sarcodina (Rhizopodia)

Question 24

Name an important type of amoeba

Answer 24

Dyctostelyum discoideum

Question 25

Why is Dictostelyum discoideum so special?

Answer 25

Haploid, unicellular, when food sources become scarce forms slug (recruits cells by signaling with cAMP, adhere by glycoproteins)

Also undergoes cell differentiation to form fruiting body —> head, contains spores, is ruptured by wind and secretes spores, can travel

Also stores bacterial cells as symbionts during this cycle to take with them as food source to their new niche

Question 26

What protozoan provides a very simple model to study aggregation and differentiation

Answer 26

Dictostelyum discoideum

Question 27

Describe the life cycle of E. hystolytica

Answer 27

Two stages in life cycle: motile amoeba (trophozoite), cyst (resistant)

Infection occurs by ingestion of cysts (generally from fecally contaminated food or water)

< Excystation occurs in the ileum of the small intestine, trophozoites formed

< Trophozoites multiply by binary fission in the large intestine. Most remain in the lumen of the intestine, however, some may invade the intestinal mucosa, enter the bloodstream and develop in extraintestinal sites. Cause symptoms

Question 28

What happens when E.hystlytica becomes invasive and attacks organs?

Answer 28

• localised infection (amoebic dysentery or traveler’s diarrhea)
• Systemic infection of many organs, including brain

Normally, no symptoms

Question 29

What causes periodontal disease and gengivitis?

Answer 29

E. gengivalis

related to E,hystolytica, but cannot form cysts and thus can only infect the mouth. Passed on by kissing.

Question 30

What are the three lineages of primary endosymbionts?

Answer 30

Chlorophyta (greens) (chl a, b)

Rhodophyta (reds) (chl a, phycobillins)

Glaucocystophyta (chl a, phycobillins)

Question 31

Which lineage in algae has given rise to all land plants?

Answer 31

Chlorophyta, after the evolution of multicellularity

Question 32

What is a primary organism to study multicellularity and cell differentiation?

Answer 32

Volvox: 2 cell types, somatic cells and germ cells

Question 33

What piece of convincing evidence for the endosymbiotic theory do glaucophytes provide?

Answer 33

The chloroplast has retained the peptidoglycan cell wall. This is a piece of convincing evidence that chloroplasts have evolve from free living gram –ve cyanobacteria.

Question 34

Secondary endosymbionts that have captured green algae

Answer 34

Chloroarachniophyta

Question 35

Secondary endosymbionts that have captured red algae

Answer 35

Cryptophyta

Question 36

What common feature do choloarachniophyta and cryptophyta share?

Answer 36

Nucleomorph (small, vestigial ek nucleus found between inner and outer pairs of membranes in certain plastids. Vestiges of primary endosymbionts’ nucleus.

Question 37

Why are Chloroarachniophyta and Cryptophyta remarkable?

Answer 37

They coordinate gene expression between 4 different genomes:

Nuclear

Mitochondrial

Chloroplast

Nucleomorph

Question 38

What chromosomes are found in nucleomorph?

Answer 38

Bonsai chromosomes: chromosomes that have been shrunk to the bare minimum. 3: minimum number of chr that you can have in the nucleus to allow proper replication (minimum required for correct association to mitotic spindle)

Question 39

How did euglena evolve?

Answer 39

Capture of green algae (3 membranes surrounding the chloroplast rather than 4, like the others described above). Basically photosynthetic trypanosomes, i.e the protozoan host was related to modern day trypanosomes

Question 40

Name 2 secondary endosymbionts that acquired their chloroplasts by secondary endosymbiosis involving red algae

Answer 40

• *Heterokontophyta:** include dyatomes and brown algae.
• *Haptophyta:** algae than can fix CO2 into chalk and organic compound (responsible for cliffs of Dover, important group in carbon fixation) Emiliana huxleyi

Question 41

How did Heterokontophyta and Haptophyta evolve?

Answer 41

Secondary endosymbiosis through capture of red algae

Question 42

What is a probable way that the apicomplexans evolved?

Answer 42

Probably through secondary endosymbiosis, capture of green algae. They have a chloroplast but have lost ability to carry out photosynthesis, but retain the compartment because it carries out other biochemical rxns e.g. fatty acid synthesis. They have a green ancestor, they have retained the plastid and its genome.

Question 43

What are dinoflagellates?

Answer 43

Tertiary endosymbionts

They acquired chloroplast from red algae from secondary endosymbiosis. Interestingly, 50% of all species have since discarded their chloroplast and returned to the heterotrophic lifestyle.

Other dino species have replaced this with one from a green alga or a haptophyte (tertiary endosymbiosis!!).

Question 44

What is kleptoplasitdy?

Answer 44

Some species have temporary chloroplasts (kleptoplastids) obtained from their algal prey and maintained for a few months, without replication and integration into cell does not happen.

Sea slugs are also an example of kleptoplastidy in the animal world. Retain the chloroplast from algae they eat, and never eat again in their lifetime. Photsynthetic animals!!!