4.6 Protists and Fungi

Question 1

Categorization of eukaryotes

Answer 1

• Excavata
• Stramenopiles
• Alveolata
• Rhizaria
• Amoebozoa
• Archaeplastida
• Opisthokonta

Question 2

Excavata types

Answer 2

Diplomonads, Parabasalids, and Euglenozoa

Question 3

Diplomonads

Answer 3

Posses mitochondrial genes in the cell nucleus as well as mitosomes

Anaerobic and acquire energy through glycolysis or other pathways

Question 4

Giardia

Answer 4

Diplomonad intestinal parasite that is non-life-threatening and causes diarrhea

Question 5

Mitosomes

Answer 5

Diplomonad intestinal parasite that is non-life-threatening and causes diarrhea

Question 6

Parabasalids

Answer 6

Very large Golgi apparatus and associated cytoskeletal elements form a parabasal body

Contain highly modified mitochondria

Anaerobic

Produce hydrogen gas as a metabolic byproduct

Some colonize guts of ruminant animals and termites since they can digest cellulose

Question 7

Trichomonas

Answer 7

Causes trichomoniasis, a sexually transmitted disease that causes vaginitis in females but is asymptomatic in males

Question 8

Euglenozoans

Answer 8

Two major groups: euglenids and kinetoplastids

Include autotrophs, heterotrophs, mixotrophs, and parasites

Stiff pellicle cell membrane consists of microtubules that spiral around cell and connect to cytoskeleton

Question 9

Euglenids

Answer 9

Type of Euglenozoan containing chloroplasts derived from secondary endosymbiosis

Question 10

Kinetoplastids

Answer 10

Type of Euglenozoan containing kinetoplast consisting of large piece of DNA inside mitochondrion

Question 11

Trypanosoma

Answer 11

Type of kinetoplastid transmitted by tsetse flies that causes African sleeping sickness

Question 12

Leishmania

Answer 12

Type of kinetoplastid transmitted by sandflies that causes leishmaniasis

Cutaneous infection causes skin sores while visceral infection affects internal organs

Question 13

Naegleria fowleri

Answer 13

“brain-eating amoeba”

Closely related to euglenozoans

Responsible for amoebic meningoencephalitis

Not a true amoeba but is an excavate with amoeboid and flagellate life stages

Lives in warm freshwater, typically ponds, lakes or reservoirs

Can infect humans by entering through the nose before migrating into the brain

Initially produces symptoms similar to meningitis but has a 95% fatality rate

Question 14

Stramenopiles

Answer 14

Include brown algae, yellow algae, and diatoms

Heterokonts: flagella face different directions

Have two flagella, one short and smooth and one long and hairy

Some are photosynthetic with chloroplasts derived from red algae

Some are heterotrophic

Include slime nets and oomycetes which are plant pathogens

Question 15

Alveolata

Answer 15

Groups: Apicomplexans, Dinoflagellates, Ciliates

Characterized by presence of alveoli which are membrane-bound sacs located beneath the cell membrane

Question 16

Apicomplexans

Answer 16

Endoparasites containing an apical complex at one end of the cell consisting of a cluster of microtubules, vacuoles, and fibrin

Apical complex only present during certain stages of the life cycle and aids in the penetration and infection of a host

Include genera Plasmodium and Toxoplasma

Meiotic divisions occur after fertilization

Question 17

Plasmodium

Answer 17

Type of apicomplexan

Transmitted by mosquitoes and causes malaria

Responsible for about half a million deaths per year

Question 18

Toxoplasma

Answer 18

Type of apicomplexan

Prenatal infection can cause severe birth defects

Reason why pregnant women must avoid raw meat and cat litterboxes

Question 19

Dinoflagellates

Answer 19

Posses two flagella oriented perpendicular to each other causing the entire organism to spin when moving

Many are photosynthetic and important primary producers in aquatic systems as a component of plankton

Some are bioluminescent

Blooms can produce a damaging “red tide” of chemicals poisonous to animals

Question 20

Zooxanthellae

Answer 20

Type of dinoflagellate that form mutualism with stony corals

Question 21

Ciliates

Answer 21

Posses rows of short cilia that form an undulating membrane used to create a current to ingest food into an oral groove

Contain two nuclei, one small micronucleus and one large macronucleus

Macronucleus functions in sexual reproduction

Macronucleus controls binary fission and non-reproductive functions such as metabolism

Question 22

Rhizaria

Answer 22

Foraminifera and Radiolaria

Mostly marine amoebas with many long, slender pseudopods

Many produce tests

Question 23

Pseudopod

Answer 23

Temporary extension of the cell that many microorganisms use to move or feed

Question 24

Foraminifera

Answer 24

AKA forams

Produce multichambered tests from calcium carbonate and other materials

Some farm photosynthetic algae that harbor the tests

Use pseudopods to move, find food and find material to build tests

Very sensitive to changes in temperature making them useful indicator species of past and present climatic conditions

Sediments of dead forams form limestone or chalk after millions of years

Question 25

Radiolarians

Answer 25

Create intricate glassy tests from silica Capture prey using sticky axopodia Component of plankton, sometimes living in colonial groups collecting symbiotic algae Sediment of dead radiolarians decay and lithify over millions of years forming chert

Question 26

Axopodia

Answer 26

Special type of pseudopod composed of an outer layer of cytoplasm supported by an inner core of cross-linked microtubules

Question 27

Amoebozoa

Answer 27

Includes naked and testate amoebas A few have large, multinucleated cells and some have multicellular stages Move by extending their slender pseudopods and shifting their cytoplasm in the direction of movement. Include slime molds, which share many similarities to fungi due to convergent evolution Some alternate between haploid and diploid stages

Question 28

Acanthamoeba

Answer 28

Amoebozoa found on unsanitized contact lenses that seriously damages the cornea of the eye

Question 29

Archaeplastida

Answer 29

Arose from heterotrophic protist ancestor that acquired a chloroplast from an endosymbiotic event with a cyanobacterium Includes glaucophytes, red algae, green algae, byrophytes, and vascular plants Can be unicellular, multicellular, or colonial Life cycles range from simple to complex

Question 30

Glaucophytes

Answer 30

Small group of freshwater algae whose chloroplasts contain a layer of peptidoglycan

Question 31

Rhodophytes

Answer 31

AKA red algae Typically multicellular and along with two other subgroups of heterokonts and green algae, are considered seaweed or kelp Photosynthetic Get their name from red accessory pigments that cover up their green chloroplasts

Question 32

Green algae

Answer 32

Divided into chlorophytes and charophytes Closely related to land plants

Question 33

Volvox

Answer 33

Chlorophyte that is a colonial organism Exhibits cell specialization with only a few cells reproducing to create daughter cells

Question 34

Ulva

Answer 34

AKA sea lettuce, a multicellular chlorophyte

Question 35

Opisthokonta

Answer 35

Categorized by their single flagellum and flattened mitochondrial cristae Includes unicellular protists including nucleariid amoebas, microsporidians, fungi, choanoflagellates, and animals (Metazoa)

Question 36

Phagocytosis

Answer 36

Food particle is engulfed by a cell via a phagosome which then fuses with a lysosome to digest the food using hydrolytic enzymes

Question 37

Phagosome

Answer 37

Food vacuole formed by pinching off a small amount of plasma membrane

Question 38

Saprobes

Answer 38

Organisms that feed on dead organisms or organic waste products

Question 39

Schizogony

Answer 39

Multiple fission that involves several nuclear divisions before the cells divide and can lead to the production of spores or sporozoites

Question 40

Protists that can produce gametes through meosis

Answer 40

Ciliates, some flagellates, and amoebas

Question 41

Conjugation (protists)

Answer 41

Two different mating types join by a cytoplasmic bridge Diploid micronuclei undergo meiosis producing four daughter nuclei, three of which degrade, and then mitosis Each cell transfers one of the two resulting nuclei to the other cell The original macronucleus disintegrates, and the micronucleus and macronucleus are reconstructed

Question 42

Bleaching

Answer 42

Coral losing pigment due to loss on zooxanthellae

Question 43

Phytophthora infestans

Answer 43

Water mold that causes potato blight and led to the Irish potato famine which killed about one million people

Question 44

Plasmodium falciparum cycle

Answer 44

Sporozoites are transmitted from mosquitos to humans In the liver, they become schizonts and release merozoites that infect red blood cells Parasites asexually reproduce in red blood cells, some undergo sexual reproduction as well Gametes ingested by a mosquito where they form zygotes Sporozoites formed in the oocysts burst out and migrate to the salivary gland

Question 45

Encephalitozoon cuniculi

Answer 45

Microsporidian that infects the brain and kidneys and may cause neurodegenerative disease Rare in humans but common in rabbits Transmitted zoonotically through spores in the urine

Question 46

Neocalllismastigomycetes

Answer 46

Fungi that obtained cellulases from bacteria Can be found in the stomachs of animals including sheep, kangaroos, and elephants

Question 47

Basidiomycetes

Answer 47

Named for reproductive structures, basidia, found in gills of their spore-forming fruiting body

Question 48

Ascomycetes

Answer 48

Have similar life cycle to basidiomycetes Many are asexual, including the single-celled yeast

Question 49

Mycelium structure

Answer 49

Formed by branching hyphae Hyphae form long chains Individual hyphae are separated by porous cross-walls called septa Septa allow the continuous flow of cytoplasm between cells

Question 50

Coenocytic hyphae

Answer 50

Not separated by septa Form large, multinucleated cells Found in bread molds

Question 51

Stages of sexual reproduction in fungi

Answer 51

Plasmogamy, karyogamy, and meiosis 1n --> 2n --> 1n

Question 52

Plasmogamy

Answer 52

Stage of fungal sexual reproduction Process of two cells fusing to bring together two haploid nuclei, producing a dikaryote Can be very long for basidiomycetes, forming secondary mycelium and the basidiocarp Some fungi use gametangia Some have no gametangia and fuse hyphae to exchange nuclei

Question 53

Karyogamy

Answer 53

Process of two haploid nuclei fusing to form a diploid nucleus

Question 54

Gametangia

Answer 54

Sex organs in fungi that produce and release gametes or fuse to bring haploid nuclei together

Question 55

Sexual reproduction in ascomycetes

Answer 55

Occurs within asci formed by the fusion of an ascogonium and antheridium The nuclei in a dikaryotic ascus fuse, forming a diploid zygote Zygote undergoes meiosis, mitosis, and cell division to form ascospores Conidiophores release asexual spores called conidia

Question 56

Ascocarp

Answer 56

Fruiting body of ascomycetes formed by the fusion of an ascogonium and antheridium

Question 57

Conidiophores

Answer 57

Modified hyphae that release conidia

Question 58

Sexual reproduction in basidiomycetes

Answer 58

Occurs withing the basidia on the basidiocarp Mycelia of two different mating types come together to form a dikaryotic secondary mycelium The secondary mycelium goes through mitosis and forms the basidiocarp and basidia Nuclei of dikaryotic basidium fuse to form a diploid zygote Zygote undergoes meiosis and divides to produce basidiospores

Question 59

Lichen

Answer 59

Symbiotic relationship between fungi and algae

Question 60

Dutch elm disease

Answer 60

Decimated elm population in North America and Europe Caused by an ascomycete fungus transmitted by bark beetles Blocks the tree’s xylem, reducing water conduction