Chapter 12 Flashcards
Phytophthora infestans
A water mold which causes a disease called late blight in potatoes
Was the cause of the Irish Potato Famine
How is Phytophthora infestans spread?
The infection is transmitted by spores, which can persist for years in the soil and are spread by wind as well as by people who handle the potatoes.
Fungi
Heterotrophic eukaryotic organisms containing chitin in the cell wall
Protozoa
Heterotrophic unicellular organisms that are not fungi
Algae
Eukaryotic photosynthetic organisms with relatively simple reproductive structures and no organized vascular system.
Protozoa and algae are grouped together as what
Protists
Protists
Usually single celled eukaryotes that are not fungi, plants or animals.
Mycology
The study of fungi
What are some forms of fungi?
Yeasts
Molds
And familiar mushroom
Yeasts
Single celled fungi
Molds
Are multicellular filamentous fungi
Mushrooms
Are simply the reproductive structures of certain fungi, similar to a peach on a peach tree
Fungi are what trophs
Fungi are heterotrophs and are among the main decomposers of organic materials, including living and cellulose
Fungi are the main decomposers of
Organic materials
Ligin
Cellulose
Saprotrophs
Are what fungi are.
Organism that takes in nutrients from dead and decaying matter.
How do fungi decompose dead or decaying organic matter
They do this by secreting enzymes into the environment to break large molecules into smaller ones that they can then absorb.
What does the overall decomposition process of fungi produce
The overall decomposition process releases carbon dioxide and nitrogen compounds, which are then taken up by various organisms and again converted into organic compounds.
Batrachochytrium dendrobatidis
Infects the skin of frogs and is believed to be responsible for the catastrophic decline in frog populations over the part two decades.
Example of fungi partnering with other organisms in mutually beneficial relationships
Fungi and algae form lichen that can grow on surfaces where neither can survive alone.
What does the cell wall of Fungi contain?
Fungi are characterized by a cell wall that contains chitin.
In addition to chitin, the cell walls typically contain glucan
Stronger than the cellulose based cell wall of plants.
Glucan
Typically in the cell wall of fungi.
Is a polymer of glucose
Glucan synthesis is the target of certain anti fungal medications
What is the target of certain anti fungal medications
Glucan synthesis
Ergosterol
Ergosterol
Substance in fungal membranes
Distinguishes them from animal cell membranes which contain cholesterol.
Dimorphic fungi
Fungi that are able to transition between two forms, usually yeast and mold, depending on the environmental conditions.
Molds
Characterized by intertwined thread like multicellular filaments called hyphae.
Hyphae
Multicellular filament that characterizes the growth of most fungi and some bacterial species.
How do fungi get food if they are generally not motile?
Because fungi are generally not motile, they cannot move toward a food; instead, the tips of hyphae respond to a nutrient source by growing in that direction.
Vegetative hyphae
Hyphae that grow into the food.
Aerial hyphae
The surface growth you see on moldy food is composed of aerial hyphae, which give rise to spores.
The powdery or fuzzy and sometimes colorful appearance of molds is due to the aerial hyphae and spores.
Conidia
Asexually produced reproductive units borne on hyphae.
The asexual responds give cells of most molds.
Sporangiospore
Term used for the asexual reproductive cells of members of the fungal phylum mucoromycota.
Conidiophores
The Conidia of some fungal species are held on Conidia bearing structures called conidiophores.
Arthroconidia
Fungal species reproducing as a result of a fragmentation of hyphae.
How are sporangiospores formed
Sporangiospores form within a sporangium
How do yeast cells reproduce
Yeast cells produce asexually by budding.
In this process, the nucleus divides by mitosis and one nucleus migrates into a smaller daughter cell, or bud
The daughter cell then pinches off from a larger parent cell.
What results from sexual reproduction of fungi
Sexual reproduction of fungi results when hyphae from two different mating types grow toward one another and fuse.
After this fusion, the cells of the fungus will often contain both haploid nuclei.
Eventually the nuclei fuse and then undergo meiosis, forming haploid spores.
Trophozoite
Growing feeding form of Protozoa
Cyst
Infectious survival form of some protozoa
The one that is transmitted from one host to the next, not the trophozoite.
Coccidia
Group of intestinal Protozoa
Oocyst
A group of intestinal Protozoa called coccidia produce an environmentally resistant form of cyst called oocyst.
This is an infectious form that can be transmitted to the next host.
Develop as part of the sexual stage.
Groups of medically significant protozoa
Amoebae
Apicomplexans
Hemoflagellates
Lumen dwelling flagellates
Amoebae
Protozoa that move by extending and retracting portions of their cytoplasm.
The combined actions send out pseudopods that not only move the cell forward, but also allow it to engulf particles.
How do amoebae reproduce
Amoebae reproduce using asexual process of binary fission, meaning that one cell splits to become two.
Intestinal amoebae
Cells lack mitochondria, so rely only on fermentation for energy transformation, some have mitosomes
Most are commensals, meaning they live in the intestinal tract without harming the host.
Mitosomes
Appear to be relics of mitochondria
Function unknown
Apicomplexans
Sometimes called sporozoa
Is a group of Protozoa that penetrate host cells by means of a structure called an apical complex.
What does apical complex of Apicomplexans do
The apical complex helps the organism penetrate the cytoplasmic membrane of host cells.
Medically important Apicomplexans are…
Obligate intracellular parasites
Obligate intracellular parasites
They require a host cell in which to replicate.
How do Apicomplexans reproduce
Sexually and asexually, often in different hosts
Definite host
Organism in which sexual reproduction or the adult form of a parasite occurs
Intermediate host
Organism in which asexual reproduction or an immature form of a parasite occurs.
Plasmodium species
Part of Apicomplexans
Cause malaria
Definite host for plasmodium species
Mosquitos
Intermediate host of plasmodium species
Humans
Hemoflagellates aka euglenozoa
Are a group of flagellated Protozoa that multiply by binary fission and live in the blood stream for part of their life cycle.
Examples of hemoflagellates
Trypanosoma
Leishmania
Lumen dwelling flagellates
Colonize the lumen of either the intestinal tract or genital tract, using flagella for movement.
Reproduce asexually using binary fission.
Example of lumen dwelling flagellate
Giardia lamblia
Trish o as vaginalis
Giardia lamblia
A flagellate that lives in the intestinal tract, among the leading causes of diarrhea worldwide.
Forms infectious cysts that survive in the environment.
Trichomonas vaginalis
Is a sexually transmitted flagellate that colonizes the genital tract.
Lack mitochondria.
Doesn’t have a cyst form.
Algae
Simple photosynthetic
Eukaryotes.
Lack organized vascular system and have relatively simple reproductive structures.
Helminths
A worm, parasitic ones often have complex life cycles.
Two general groups Helminths are divided into
- Roundworms (nematodes)
- Flatworms (platyhelminths)
Roundworms (nematodes)
A Helminths that has a cylindrical tapered body.
Has a digestive tract that extends from the mouth to the anus.
Flatworm (platyhelminth)
A Helminth with a flat body form; further divided into the tapeworms (cestodes) and flukes (trematodes)
Flatworms are further divided into what two groups
- Tapeworms (cestodes)
- Flukes (trematodes)
Tapeworm (cestodes)
A helminth that has a segmented, ribbon shaped body.
Have no digestive system
Do not feed directly on the tissues of their hosts.
Parts of a tapeworm (cestodes)
- Scolex
- Proglottids
Scolex
Head end of tapeworm
May have suckers and hooks for attachment
What is the Proglottids furthest from the scolex contain
Fertilized eggs
Flukes (trematodes)
Short, no segmented, bilaterally symmetrical flatworm.
Parts of the flukes
Has two suckers
Mouth
No anus
Hookworms
Type of nematode
How do hookworms spread
The larvae of hookworms live in the soil and can burrow through human skin.
The adult worms live in the human digestive tract, where the female worm lays eggs that are eliminated with feces.
The eggs hatch in the soil, giving rise to more larvae.
When sanitation is poor and people are barefooted, the parasite is easily transmitted.
Parts of a tapeworm (cestodes)
- Scolex
- Proglottids
