Eukaryotic Microbial Cells

eukaryotic cells are generally _______ than prokaryotes

bigger

all eukaryotic cells have a _______

nucleus

mitochondria and chloroplasts have their own _______ and _________

DNA / ribosomes

can mitochondria and chloroplasts self-replicate?

yes

site of ATP/organic molecule (via rubisco in chloroplasts) production in eukaryotes

matrix/stroma

many bacteria have _______ homologs

RuBisCO

• displays evolutionary relationship

LUCA must have been a …

free living, unicellular microorganism that lacked the ability to perform respiration

describe endosymbiotic origin of some organelles

• LUCA engulfed a bacterial cell w ability to carry out respiration

• primary endosymbiosis → mitochondria & chloroplasts

• secondary endosymbiosis → cell with an endosymbiont is engulfed by another eukaryotic cell

• over time, symbiont sheds essential functions & relies more on host cell for them while providing benefit to the host

how did mitochondria & chloroplasts come to be?

primary endosymbiosis

secondary endosymbiosis

occurs when cell that already had an endosymbiont is engulfed by another eukaryotic cell

4 broad groupings of eukaryotic microbes

1. fungi

2. algae

3. protozoa

4. helminths

amoeba

• protozoa with no truly defined shape

• found in water sources

• few cause disease

• BAD protozoa

diseases caused by amoebas:

• entamoeba histolytica (a form of dysentary)

• naegleria fowleri (brain-eating amoeba)

• acanthamoeba (contact lens)

flagellates

• all have flagella (different from bacteria) composed of microtubules

• found in water/soil/human sources

common flagellate diseases

• trichomonas vaginalis (common STI)

• giardia lamblia (common in hikers who drink un-purified water)

• trypanosma (cruzi causes Chagas disease & bruci causes African sleeping sickness, transmitted from tsetse fly bites)

• leishmania (causes painful blisters on skin, transmitted via sandfly bites)

cilliates

• all have cilia (hair-like projections allowing them to move)

• have 2 nuclei + other specialized structures

• found in almost all ecosystems

• paramecium

• don’t really cause disease (1 disease = balantidium coli, zoonotic disease w pigs as primary host)

2 notable structures of cilliates

1. vestibulum

2. buccal cavity

apicomplexans

• non-motile

• 4-5 membranes

• have specialized structure called apicoplast, derived from secondary symbiotic event where a eukaryotic cell engulfed a chloroplast-containing cell

• intracellular parasites (infect cells directly)

• difficult to treat

• take on our cell membrane when they infect us

list common bad protozoa

1. amoeba

2. flagellates

3. ciliates

4. apicomplexans

apicoplast

specialized structure in apicomplexans derived from secondary symbiotic event where a eukaryotic cell engulfed a chloroplast-containing cell

disease-causing apicomplexans

• plasmodium (malaria, spread by mosquitos, replicates in red blood cells)

• toxoplasma gondii (toxo, cats harbor this parasite → why pregnant women shouldn’t change litter box)

• babesiosis (spread via ticks, present in Midwest)

list non-protozoan, eukaryotic microorganisms

• fungi

• yeast

• molds

fungi

• multi-cellular

• important pathogens & industrial species

• macro & microscopic

• many antiobiotics derived from fungi

many antibiotics, including Penicillin, are derived from _______

fungi

fungi have ______ in their lipid bilayers, similar to eukaryotes but have ________ instead of cellulose or glycogen in their cell walls

sterols / chitin

molds

• multi-cellular

• non-macroscopic mushrooms

• made up of filaments called hyphae

hyphae

• filaments that make up mold

• can form tangled network called mycelium

• can form thallus (body) of fleshy fungi

mycelium

tangled network of hyphae

yeast

• unicellular fungi

• eukaryotic

• forms psudohyphae (cells never truly split up bc unicellular)

dimorphic fungi

• can exist as both mold & yeast

• switch b/w state is governed by environmental factors including humidity & temp

• hard to treat & detect

how many membranes would you pass thru going from outside the cell into the matrix of a mitochondria?

3

• 2 mitochondrial

How many membranes might I pass through (and which ones) if I wanted to gain access to the interior of the apicoplast using an anti-biotic on a patient infected with malaria?

5-6

Why might eukaryotic organisms be harder to treat than bacterial or viral infections using conventional antibiotics and antivirals and antifungals?

• they lok like our cells, so they’re harder to target

• may have 5-6 membranes

are eukaryotic microorganism cell walls more similar to archaea or bacteria?

archaea

all eukaryotes harbor an ___________ (some have multiple)

endosymbiont