Lecture 3: Eukaryotes Flashcards
What are chemoheterotrophs?
Decompose organic matter to obtain energy.
Describe how facultative anaerobes function.
They prefer oxygen or aerobic environments but they can switch to fermentation or anaerobic respiration if oxygen is not available.
Fungi tend to be ________, and to grow in ________
multicellular; colonies
What are hyphae?
Long filaments of cells joined together.
What are septa?
Contain cross walls
What is a thalus?
The whole body of mold.
How do vegetative hyphae obtain nutrients?
By catabolism
What do aerial hyphae do?
Reproduce
How are yeast different from most other fungi?
They are unicellular and non-filamentous.
How do yeast divide?
By budding or fission
The most pathogenic species of fungi often exhibit _________, two forms of growth.
Dimorphism; they can grow as mild or yeast
How do fungi reproduce?
Either sexually or asexually via formation of spores that detach from the parent.
How are asexual spores produced?
Produced by mitosis and subsequent cell division.
What does conidiospore mean?
Not enclosed in a sac.
What does sporangiospore mean?
Enclosed in a sac.
Talk about fusion of sexual spores…
If one spore does not find another complementary spore (opposite polarity) it will simply die. If it does mate it will fuse directly.
Plasmogamy (first phase of sexual reproduction)
Haploid donor cell nucleus (+) penetrates cytoplasm of recipient cell (-)
Karyogamy (second stage of sexual reproduction)
(+) and (-) nuclei fuse and form a diploid zygote
Meiosis (third stage of sexual reproduction)
Diploid nucleus produces haploid nuclei (sexual spores).
What are some nutritional adaptations that are complementary for fungi?
- Grow better at pH of 5
- Grow in high sugar and salt concentration; resistant to osmotic pressure
- Can grow in low moisture content
- Can metabolize complex carbohydrates
Zygomycota
Black fungus (1050 species known)
Microsporidia
Do not have mitochondria. Mainly related with deficiency of immune system such as AIDS patients, kids etc.
Ascomycota
Largest phylum of fungi with 64,000 species.
Basidiomycota
Includes: mushrooms, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and the human pathogenic yeast Cryptococcus.
Basidiomycota are filamentous fungi composed of hyphae (except for yeasts), and reproducing sexually via the formation of specialized club-shaped end cells called basidia that normally bear external meiospores (usually four) called basidiospores.
Cutaneous mycoses
Fungal infection that can grow in all the layers of the skin, affecting hair, skin and nails.
Systemic mycoses
Fungal infection deep within the body such as in the lung or large intestine.
Subcutaneous mycoses
Fungal infection beneath the skin.
Superficial mycoses
Localized fungal infection, eg. hair shafts
Opportunistic mycoses
Fungi that are harmless in normal habitat but pathogenic in a compromised host.
Economic effects of fungi
- Produces citric acid
- Used to make bread, wine,
- Genetically engineered to make hepatitis B vaccine
- Used to make cellulase
- Biological control agents of pests
- Kills termites
What are lichens?
Mutualistic combination of green algae and fungus.
Lichens are in the kingdom of Fungi and have 3 major categories…
- Crustose - encrusted on the substratum
- Foliose - leaflike
- Fruticose - fingerlike
What is the thallus (body) of a lichen made of?
Medulla—hyphae grown around algal cells
Rhizines (holdfasts)—hyphae projections below the body
Cortex—protective coating over the algal layer
Lichens effects on industry
Dyes
Antimicrobial (Usnea)
Litmus
Food source for herbivores
What are algae?
- Eukaryotic
- Not a taxonomic group
- Unicellular or filamentous photoautotrophs
- Lack roots, stems, and leaves
- Mostly aquatic
- Reproduce sexually or asexually
Characteristics of algae
Locations depend on nutrient availability, wavelengths of light, and surfaces to attach
Thallus: body of multicellular algae
Consists of holdfasts, stipes, and blades
Types of algae
Brown Red Green Diatoms Dinoflagellates Oomycota
Brown algae
Also known as kelp!
- Cellulose and alginic acid cell walls
- Multicellular and macroscopic
- Produces algin, a thickener used in food
Red algae
- Have branched thalli, most are multicellular
- Harvested for agar or carageenan
- Some produce a lethal toxin
Green algae
- Cellulose cell walls, unicellular or multicellular
- Store starch
- Form scum on ponds
Diatoms
- Unicellular or filamentous with complex cell walls
- Stores oil
- Produces domoic acid that can cause neurological disease
Dinoflagellates
- Unicellular or filamentous with complex cell wall
- Neurotoxins that can cause paralytic shellfish poisoning
Oomycota (water molds)
- Cellulose cell walls
- Chemoheterotrophic
- Produce zoospores
- Decomposers and plant parasites
Give some examples of oomycota plant parasites
1) Phytophthora infestans responsible for Irish potato blight
2) P. cinnamoni infects Eucalyptus
3) P. ramorum causes “sudden oak death”
What are the roles of algae in nature?
- Fix CO2 into organic molecules
- Produce 80% of Earth’s O2
- Algal blooms are increases in planktonic algae that can result in toxin release or die and consume oxygen
- Oil production
- Symbionts of animals (in the life cycle of animals)
What are protozoa?
Unicellular eukaryotes
Chemoheterotrophs, Inhabit water and soil
Animal-like nutrition
How do protozoa reproduce?
- Asexual reproduction is by fission, budding, or schizogony (multiple fission)
- Sexual reproduction is by
- Conjugation
- Gamete formation
- Some produce a cyst to survive adverse conditions
Characteristics of protozoa
Require a large supply of water
Many have an outer protective pellicle, requiring specialized structures to take in food
Ciliates wave cilia toward mouthlike cytosome
Amebae phagocytize food
Food is digested in vacuoles and wastes eliminated through an anal pore
What are the medically important protozoa? (5)
Feeding grooves Euglenozoa Amebae Apicomplexa Ciliates
How do amebae move?
By extending pseudopods
Entamoeba histolytica
Causes amebic dysentery
Acanthamoeba
Infects corneas and causes blindness
Balamuthia
Granulomatous amebic encephalitis
Apicomplexa, describe and give 2 examples
- Large phylum of parasitic protists
- Nonmotile
- Obligate intracellular parasites
- Complex life cycles
1) Toxoplasma gondii—transmitted by cats; causes fetal infections, born alive but usually do not survive.
2) Cryptosporidium—transmitted via feces; causes waterborne illness
What phylum does Plasmodium belong to and what does it do?
Apicomplexa; causes malaria.Sexually reproduces in the Anopheles mosquito
A mosquito injects a sporozoite into its bite, and the sporozoite undergoes schizogony in the liver; merozoites are produced
Merozoites infect red blood cells, forming a ring stage inside the cell
Red blood cells rupture, and merozoites infect new red blood cells
How do ciliates move?
With cilia arranged in precise rows.
What ciliate causes dysentery?
Balantidium coli; affects humans only
What are helminths?
Multicellular eukaryotic parasitic worms that are specialized to live in hosts.
What are the main characteristics of helminths?
- May lack a digestive system
- Reduced nervous system
- Reduced or lacking locomotion
- Complex reproductive system
What are the two phyla under the kingdom of helminth?
- Platyhelminthes (flatworms)
2. Nematoda (roundworms)
Types of life cycle of a helminth?
- Dioecious: separate male and female
- Monoecious (hermaphroditic): male and female reproductive systems in one animal
Egg larva(e) adult
What are trematodes?
- Type of platyhelminth
- Called Fluke, Paragonimus (lung fluke), or Schistosoma (blood fluke).
- Flat, leaf-shaped parasite
- Ventral and oral sucker
- Absorb food through cuticle covering
What are cestodes?
Tapeworms, intestinal parasites (type of platyhelminth).
- Absorbs food through cuticle
- Humans can be definitive or intermediate host eg. Taenia solium or pork tapeworm
What is a scolex?
Cestode head that has suckers for attachment.
What is a proglottid?
Body segment of a cestode, contains male and female reproductive organs.
What is a roundworm?
A type of roundworm.
- Cylindrical with complete digestive system
- Dioeceious, males contain spicules
- Free-living and parasitic
- Eggs or larvae may infect humans.
Give three examples of roundworms that can infect humans?
- Ascaris lumbricoiedes
- Trichuris trichiura - whipworm
- Enterobius vermicularis - pinworm
What are arthropods?
Animals with segmented bodies, hard external skeletons and jointed legs.
Give 3 classes of arthropods?
- Arachnida - eight legs
- Crustacea - four antennae
- Insecta - six legs
What are the general characteristics of a virus?
Obligatory intracellular parasites (require living host cells to multiply) Contain DNA or RNA Contain a protein coat No ribosomes No ATP-generating mechanism
