Topic 4 - Eukarya Flashcards
morphology of typical eukaryotes
- membrane-bound nucleus
- larger than bacterial or archaeal cells
- contains organelles
- possess a cell wall and complex internal cytoskeleton
peroxisome
breaks down fatty acids
hydrogenosome and where are they found?
- production of H2 and ATP
- aids in fermentation (H2 gas, ATP)
- found in some amitochondriates
the nucleus
- storage and expression of information
- double membrane
- contains linear chromosomes of cell
- non-membrane bound nucleolus exists within nucleus (ribosome synthesis)
- spatial separation
– transcription occurs in nucleus
– translation occurs in cytoplasm
secretory pathway
- uses ER/Golgi apparatus
(where proteins are often modified before reaching destinations)
mitochondria
- plays a role in cell metabolism - TCA cycle (Krebs cycle)
- uses electron transport chains to produce ATP (chemiosmosis via proton motive force)
- organic carbon gives up electrons
- surface area for ETC and ATP synthesis
chloroplasts
- role in cell metabolism
- use electron transport chains to produce ATP (chemiosmosis via proton motive force)
- use produced ATP to fix carbon into organic compounds (e.g., glucose)
- water loses electron instead of organic carbon (like in mitochondria)
both mitochondria and chloroplasts are ______, meaning?
semi-autonomous
- each has a DNA genome, ribosomes, and transcription machinery
- replicates independently
- most of proteins originate from DNA in cell nucleus
- divide like bacteria (binary fission), contain bacteria-like genomes
plasma membrane
- phospholipid bilayer with embedded proteins that allow molecule transport
– facilitated (no ATP) and active (ATP) - involved in homeostasis
- fewer proteins on eukaryal plasma membranes because they went in double membranes of mitochondria and chloroplasts
- have sterols (not in archaea or bacteria)
cell wall
- some eukaryotes have cell walls (fungi, algae, etc)
- cell support
fungi & algae cell wall composed of?
chitin
cellulose
cellulose and chitin structure
use specific beta-1,4-glycosidic bonds between sugars
- strength and rigidity
- same NAG in bacterial, slight differences
cytoskeleton
- has a role in cell structure
- more extensive in eukaryotes
- comprised of three major pieces
– microtubules (tubulin)
– microfilaments (actin)
– intermediate filaments (various proteins)
(each differs in structure/function; all contribute to cell shape)
cytoskeleton is involved in ________
intracellular trafficking, motion, cell division
cell division is assisted by _____
spindle fibers
eukaryal vs bacterial flagella
eukaryal:
- more flexible-
nine microtubules doublets form a tube around a core pair of microtubules (axoneme) (9+2 array)
- motion occurs w ATP, helping microtubules in axoneme slide past ach other
- has a membrane (keep ATP in), built from distal tip
bacterial:
- nonflexible hollow
- extends outside cell membrane and cell wall
- also build from distal tip
- arrangement: polar or peritrichous
- PMF energy
Eukaryal cilia/flagella diagram parts
transport vesicle attached to kinesin which “walks” along microtubule
___ can exploit the cytoskeleton
pathogens
most eukarya are ___
microorganisms
what macroorganisms are eukaryotes
animals and plants
how many times did endosymbiosis happen? just once?
a few times, for the diff algaes (brown, red, green)
what are some highly conserved genes that we can study to understand eukaryal phylogeny?
tubulins, heat shock proteins, etc
4 eukaryal microbes categories
- fungi
- protozoa
- slime molds
- algae
which two eukaryal microbes can use amoeboid: pseupod?
protozoa (some, some others swim w cilia/flagella)
slime molds
____ is polymerized/depolymerized by amoeba to move (pseudopods)
actin
model organism - fungi
Saccharomyces cerevisiae
- heterotrophic, chitin cell wall
fungal phylogeny (5 types + short desc)
1) Chytridiomycota - early branching, “watermolds”, Laurel Creek banks
2) Zygomycota - Rhizopus (bread mold), lab contamination
3) Glomeromycota - mycorrhizal fungi - important for plants!
4) Ascomycota - “spore shooters”, cup/sac fungi, yeast
5) Basidiomycota - “spore droppers”, club fungi, traditional mushroom-producing fungi
Protozoa
- very broad category
- some heterotrophic, some photosynthetic
- variable cell walls
- diff motility strats
- diff reproduction strats
protozoa - amitochondriate example
Giardia lamblia
- genetically “old”, lacks mitochondria
- causes human disease
- diarrhea from unfiltered water
slime moulds - model organisms (2)
protozoa
- Dictyostelium discoideum (study ecology, cell motility, cell-cell communication)
- Physarum (fuses many cells into a continuous, multinucleate giant cell)
algae characteristics (short) + model organism
- many are multicellular
- all are photosynthetic with cellulose cell walls
- Chlamydomonas:
– two-flagella form (study eukaryal flagella biogenesis/function)
– can mess w pH to watch flagella regrow
Eukaryal replication
- more complicated due to haploid/diploid states
- possible for sexual or asexual reproduction
mitosis
- produces two identical daughter cells from one original cell
- diploid to diploid OR haploid to haploid
meiosis
- four haploid cells from one original diploid cell
- one round of DNA replication followed by two rounds of cell division
- segregation of maternal/paternal chromosomes
- “crossing over” between chromosomes prior to segregation
- ensures each haploid cell is genetically distinct
- first meiotic cell division -> two haploid cells
- second meiotic cell division -> four haploid cells
Saccharomyces life cycle
- can undergo meiosis to form an ASCUS (skin bag)
- haploid mating types can fuse to reproduce sexually or be maintained by asexual mitosis
- meiosis under unfavourable conditions
- not limited to ascus formation
- budding off of smaller cells can occur, or fission of identically sized cells
Chlamydomonas life cycle
- maintains a motile haploid state
- haploid cells differentiate and fuse into a diploid form in bad conditions - SPORE formation
Dictyostelium life cycle
- exists in a haploid unicellular form until conditions worsen
- multicellular “slug” is formed with a stalk and a fruiting body
- spores form in fruiting body, restarting life cycle as haploid cells
- haploid cells can fuse into a diploid macrocyst form
- MACROCYST form undergoes meiosis to make haploid cells
when did life start?
4.5-4 bya
when did eukaryotes first appear?
2.1-1.6 bya
which came first, mitochondria or chloroplast?
mitochondria, then chloroplast
evidence for endosymbiotic theory
- mitochondria/chloroplasts resemble bacteria in both size and shape
- double membranes, binary fission
- division with FtsZ
- each has its own DNA, rRNA more similar to bacteria
- circular chromosome
exception for endosymbiotic theory + example
amitochondriates, which likely evolved out of using them to obtain energy (e.g., Giardia)
endosymbiosis in modern cells (experiment)
algae infected with x-bacteria
- the algae that survived died with antibiotics (meaning they became dependent on bacteria for survival)
Paramecium ingests ___ to use them for__?
algae
photosynthesis
diseases caused by eukaryal microbes
- protozoa can cause BIG diseases (e.g., malaria, african sleeping sickness)
- difficult to treat as we are eukaryotes
- fungi are less likely to cause disease but cam in immuno-comprised humans (e.g., oral thrush, athlete’s foot)
- protozoa and fungi can cause BIG diseases in plants (e.g., tar spots, potato blight famine)
what microbe caused the potato blight and great irish famine? (exact name)
Phytophthora infestans (fungus)
beneficial roles of eukarya microbes
- primary producers provide energy
(some algae produce a ton of O2 in ocean) - biodegraders recycle nutrients
- some eukaryal microbes can degrade cellulose recycling plant matter better than animals can
