BIOL240 Module 4 Eukaryotes

Amitochondriates

Eukaryotes without a mitochondria

Chemiosmosis

Moving chemicals down concentration gradients, across membranes, between two spaces

Cellulose

Algae and plant wall cells → Glucose monomers linked by β-1-4-glycosidic bonds

Chitin

Fungi cell walls → unique sugar molecules, repeat NAG

Tubulin

Microtubules

Homologue of FtsZ protein w/in bacteria

Purpose of microtubules

Spindle fibers → assist in cell division

Actin

Microfilaments

Homologue is MreB in bacteria

Axoneme

Rows of microtubules that form the core structure of cilia and flagella, enabling movement.

Fungi

Heterotrophic

Chitin cell walls

Nucleus and mitochondria

Protozoa

Some heterotrophic, some photosynthetic

Variable cell walls

Different motility and reproduction strategies

Slime Molds

Heterotopic

Usually no cell walls

Nucleus and mitochondria

Algae

Phototrophic or photosynthetic

some non-motile, some flagella

Cellulose cell wall

Saccharomyces cerevisiae, “brewer's yeast.”

Model organism for Fungi

Ferment during their anaerobic metabolism

Giardia lamblia

Model organism for Protozoa

Lacks mitochondria → rely on fermentation

Dictyostelium discoideum

Model organism for slime molds

Used to study cell communication, ecology of organisms, and cell motility

Chlamydomonas

Model organism for Algae

Useful to study flagella

Replication/Life Cycle of Saccharomyces cerevisiae

• Meiosis to form an ascus

• Haploid mating types can fuse to reproduce sexually or be maintained by asexual mitosis

Replication/Life Cycle of Chlamydomonas

• Motile haploid state

• Haploid cells differentiate and fuse into diploid form (spore)

Replication/Life Cycle of Dictyostelium

• 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.

Mitosis

Two identical cells from one original cell

Meiosis

Four haploid cells from one original diploid cell

Evidence for Endosymbiosis

1. Look like and divide like bacteria

2. Has double membranes

3. Has their own DNA

Protozoal Infections

Malaria and African Sleeping Sickness

Fungal infections

Oral Thrush —> Candida albicans

Athletes Foot

Phytophthora (Potato Blight)

A plant pathogen that causes late blight in potatoes and tomatoes, leading to significant agricultural losses.

Has features of Fungi and Algae → considered fungi

Rhytisma (Tar Spots)

Black spots on leaves

More likely in areas in low levels of air pollution

Cordyceps

Infects arthropods

Valued for pharmaceutical properties