Topic 4: Microbial Eukaryotes

Question 1

E vs P: Nucleas

Answer 1

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

Question 2

E vs P: Ribosomes

Answer 2

E + P: Contain Ribosomes

Question 3

E vs P: Mitochondria

Answer 3

E: - “Powerhouse” of the cell
- semi-autonomous
- Double membrane
- Contains some DNA
- Cell metabolism (Krebs Cycle)
P: No mitochondria

Question 4

E vs P: Chloroplast

Answer 4

E: - Photosynthesis
- Semi-autonomous
- Double membrane
- cell metabolism
P: No chloroplast

Question 5

E vs P: Rough ER

Answer 5

E: - Has ribosomes attached to it
- Site of translation and protein folding
- Part of the secretory pathway
P: No rough ER

Question 6

E vs P: Golgi apparatus

Answer 6

E: - Connected to the ER through a series of vesicles
- Modifies, sorts, and transports proteins
- Part of the secretory pathway
P: No Golgi apparatus

Question 7

E vs P: Vacuole

Answer 7

E: storage and structure
P: small vacuoles

Question 8

E vs P: Lysosome

Answer 8

E: - Digestion of macromolecules
- Contains digestive enzymes
P: no lysosome

Question 9

E vs P: Peroxisome

Answer 9

E: - Breakdown of fatty acids
- Contains different oxidative enzymes
P: no peroxisome

Question 10

E vs P: Hydrogenosome

Answer 10

E: production of H2 and ATP
P: no hydrogenosome

Question 11

E vs P: Plasma membrane

Answer 11

E: phospholipid bilayer
P: surrounded by a plasma membrane

Question 12

E vs P: Cell wall

Answer 12

E: - B1,4 glycosidic bonds
- made of cellulose (fungi and plants) or chitin (fungi)
P: - Composed of peptidoglycan (bacteria) or pseudo murein (archaea)

Question 13

Fungi

Answer 13

Metabolism: Heterotrophic
Motility: Normally non-motile
Cell Wall: usually yes, chitin
Nucleus: yes
Mitochondria: yes
Chloroplast: No

Question 14

Protozoa

Answer 14

Metabolism: Hetereotrophic
Motility: Varied
- Swimming: cilia/flagella
Amoeboid: pseudopods
Cell Wall: typically no
Nucleus: yes
Mitochondria: typically yes
Chloroplast: no

Question 15

Slime molds

Answer 15

Metabolism: Heterotrophic
Motility: amoeboid, pseudopods
Cell Wall: typically no
Nucleus: yes
Mitochondria: yes
Chloroplast: no

Question 16

Algae

Answer 16

Metabolism: Phototrophic
Motility: non motile or swimming: flagella
Cell Wall: typically yes, cellulose
Nucleus: yes
Mitochondria: yes
Chloroplast: yes

Question 17

Model Organism: Fungi

Answer 17

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

Question 18

Model Organism: Protozoa

Answer 18

Giardia lamblia
- Genetically “old”, lacks mitochondria
- Causes human disease
- fermentation

Question 19

Model Organism: Slime molds

Answer 19

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.

Question 20

Model Organism: Algae

Answer 20

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)

Question 21

Explain endosymbiosis and provide evidence for this theory

Answer 21

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

Question 22

List causative agents of selected eukaryotic microbial diseases and describe their characteristics

Answer 22

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

Question 23

Mitosis

Answer 23

produces two identical cells from one original cell.

Question 24

Meiosis

Answer 24

produces four haploid cells from one original diploid cell.