Topic 4: Microbial Eukaryotes Flashcards
E vs P: Nucleas
E: - Plays a role in storage and expression of information
- Double membrane structure
- Contains linear chromosomes of cell
Site of transcription
P: - No membrane bound organelles
- Most have a single circular molecule of DNA in the central area of the cell called the nucleoid
- Not surrounded by a nuclear membrane
E vs P: Ribosomes
E + P: Contain Ribosomes
E vs P: Mitochondria
E: - “Powerhouse” of the cell
- semi-autonomous
- Double membrane
- Contains some DNA
- Cell metabolism (Krebs Cycle)
P: No mitochondria
E vs P: Chloroplast
E: - Photosynthesis
- Semi-autonomous
- Double membrane
- cell metabolism
P: No chloroplast
E vs P: Rough ER
E: - Has ribosomes attached to it
- Site of translation and protein folding
- Part of the secretory pathway
P: No rough ER
E vs P: Golgi apparatus
E: - Connected to the ER through a series of vesicles
- Modifies, sorts, and transports proteins
- Part of the secretory pathway
P: No Golgi apparatus
E vs P: Vacuole
E: storage and structure
P: small vacuoles
E vs P: Lysosome
E: - Digestion of macromolecules
- Contains digestive enzymes
P: no lysosome
E vs P: Peroxisome
E: - Breakdown of fatty acids
- Contains different oxidative enzymes
P: no peroxisome
E vs P: Hydrogenosome
E: production of H2 and ATP
P: no hydrogenosome
E vs P: Plasma membrane
E: phospholipid bilayer
P: surrounded by a plasma membrane
E vs P: Cell wall
E: - B1,4 glycosidic bonds
- made of cellulose (fungi and plants) or chitin (fungi)
P: - Composed of peptidoglycan (bacteria) or pseudo murein (archaea)
Fungi
Metabolism: Heterotrophic
Motility: Normally non-motile
Cell Wall: usually yes, chitin
Nucleus: yes
Mitochondria: yes
Chloroplast: No
Protozoa
Metabolism: Hetereotrophic
Motility: Varied
- Swimming: cilia/flagella
Amoeboid: pseudopods
Cell Wall: typically no
Nucleus: yes
Mitochondria: typically yes
Chloroplast: no
Slime molds
Metabolism: Heterotrophic
Motility: amoeboid, pseudopods
Cell Wall: typically no
Nucleus: yes
Mitochondria: yes
Chloroplast: no
Algae
Metabolism: Phototrophic
Motility: non motile or swimming: flagella
Cell Wall: typically yes, cellulose
Nucleus: yes
Mitochondria: yes
Chloroplast: yes
Model Organism: Fungi
Saccharomyces cerevisiae
- “brewers yeast” (used to make bread, beer and wine)
- ferments during anaerobic metabolism
- cell wall of chitin (NAG, NAG, NAG)
- heterotrophic
- easy to grow, cheap
- can learn a lot about human cells from studying yeast cells
simple life cycle
— Can undergo meiosis to form an ascus (not limited to ascus formation)
— Haploid mating types can fuse to reproduce sexually or be maintained by asexual mitosis
— Budding off of smaller cells can occur or fission of same sized cells
Model Organism: Protozoa
Giardia lamblia
- Genetically “old”, lacks mitochondria
- Causes human disease
- fermentation
Model Organism: Slime molds
Dictyostelium discoideum
- technically also considered within protozoa
- used as model for studying how cells communicate with one another
- for studying the ecology of organisms
- how organisms interact with their environment and with other organisms
- for studying cell motility
- can be readily grown in a lab
Life cycle
— Asexual/vegetative cycle: Haploid unicellular form
— Sexual cycle: Haploid cells fuse into a diploid macrocyst, followed by meiosis to generate more haploid cells
—Social cycle: Multicellular “slug” formed with a stalk and a fruiting body. Spores form in the fruiting body, restarting life cycle as haploid cells.
Model Organism: Algae
Chlamydomonas
- easy to grow
- useful for studying flagella
- large chloroplasts
- have red dots inside of the cell called “eye spots,” which are made up of carotenoid pigments, used to detect light and help find way to correct light density
Life Cycle:
— Motile haploid state
— Haploid cells differentiate and fuse into diploid form (spore)
Explain endosymbiosis and provide evidence for this theory
One primitive microbe ingested another, forming a symbiosis
Mitochondria and chloroplasts (evidence)
- resemble bacteria in both size and shape
- have “cell” division with FtsZ
- have double membranes (host and bacterium)
- have circular chromosome like bacteria
- have their own DNA; rRNA more similar to bacterial sequences than eukaryal ones
List causative agents of selected eukaryotic microbial diseases and describe their characteristics
Protozoa: Giardia can cause diseases to humans, like “beaver fever”/”hikers diarrhea”, infections like malaria and African sleeping sickness, treatments are toxic to human cells
Fungal infections: oral thrush, athletes foot
- Among humans, only serious for immunocompromised individuals
- Phytophthora causes Potato Blight; reason for Irish famine in mid-1800s
- Rhytisma causes Tar Spots on tree leaves (e.g., Maples)
- Cordyceps infects arthropods; valued for pharmaceutical properties
Mitosis
produces two identical cells from one original cell.
Meiosis
produces four haploid cells from one original diploid cell.
