Raven Biology, CH28 Protists

`13th edition of Raven biology chapter 28 on Protists

Eukaryotic Origins, Eukaryotic cells differ from prokaryotes

Presence of a complex cytoskeleton

Eukaryotic Origins, Eukaryotic cells differ from prokaryotes in their

Compartmentalization (nucleus and organelles)

Eukaryotic Origins, Appearance of eukaryotes in microfossils occurred about

1.5 BYA

Eukaryotic Origins, The nucleus and endoplasmic reticulum arose from

Infoldings of prokaryotic cell membrane

Overview of Protists, Protists are the most diverse of the four eukaryotic kingdoms

United on the basis that they are not fungi, plants, or animals (classified by exclusion)

Overview of Protists, Protists vary considerably in every other aspect

Unicellular, colonial, and multicellular groups; most are microscopic but some are huge; many forms and symmetries; all types of nutrition

Evidence for endosymbiosis, Endosymbiosis is supported by DNA inside mitochondria and chloroplasts

Circular DNA, similar to bacteria DNA in size and character

Evidence for endosymbiosis, Ribosomes inside mitochondria are similar to bacterial ribosomes and are

Vulnerable to antibiotics

Evidence for endosymbiosis, Chloroplasts and mitochondria replicate by

Binary fission – not mitosis

Evidence for endosymbiosis, Mitosis evolved in

Eukaryotes

Mitosis evolved in eukaryotes, Prokaryotes carry genes on a

Single DNA molecule

Mitosis evolved in eukaryotes, Eukaryotes have

Multiple chromosomes

Mitosis evolved in eukaryotes, Mitosis and cytokinesis developed to separate

Chromosomes and other cell contents during cell division

Protists are present in all eukaryotic supergroups, Protists are not monophyletic

They are paraphyletic

Protists are present in all eukaryotic supergroups, Protists are present in all five eukaryotic supergroups

Excavata, SAR, Archaeplastida, Amoebozoa, Opisthokonta

Cell surface in protists, Protists have varied array of cell surfaces

Plasma membrane

Cell surface in protists, Some protists have an

Extracellular matrix (ECM)

Cell surface in protists, Diatoms and foraminifera have

Silica shells

Cell surface in protists, Cysts are

Dormant cell with resistant outer covering

Cell surface in protists, Cysts are used for

Disease transmission

Locomotion in protists, Flagella

One or more

Locomotion in protists, Cilia are

Shorter and more numerous than flagella

Locomotion in protists, Pseudopodia ("false feet") are the

Chief means of locomotion for amoebas

Locomotion in protists, Pseudopodia are used by

Other protists as well

Nutrition in protists, Autotrophs include

Some photosynthetic and some chemoautotrophic

Nutrition in protists, Heterotrophs include

Phagotrophs – ingest particulate food matter

Nutrition in protists, Mixotrophs are both

Phototrophic and heterotrophic

Reproduction in protists, Asexual reproduction is the

Typical mode of reproduction

Reproduction in protists, Some species have an unusual

Mitosis

Reproduction in protists, Mitosis produces

Equal size daughter cells

Reproduction in protists, Budding produces

One daughter cell smaller

Reproduction in protists, Schizogony is cell division preceded by several nuclear divisions and produces

Several individuals

Reproduction in protists, Sexual reproduction

Some regularly reproduce sexually, some under

Reproduction in protists, Meiosis is a major

Eukaryotic innovation

Reproduction in protists, Sexual reproduction involves union of haploid gametes which are produced by

Meiosis

Reproduction in protists, Advantage of sexual reproduction is allowing

Frequent genetic recombination

Diplomonads, Diplomonads are

Unicellular

Diplomonads, Diplomonads move with

Multiple flagella

Diplomonads, Giardia is a

Parasite

Parabasalids, Some parabasalids live in

Termite guts

Parabasalids, Trichomonas vaginalis is an

STD causing trichomoniasis

Parabasalids, Trichomonas vaginalis uses an undulating membrane and

Flagella for locomotion

Euglenozoa, a. Euglenids are

Unicellular

Euglenozoa, a. Euglenids, Euglenids can be both

Autotriphic and herterotrophic

Euglenozoa, a. Euglenids, Euglenids have a flexible

Pellicle

Euglenozoa, a. Euglenids, Euglenids have a red

Eyespot

Euglenozoa, b. Parasitic kinetoplastids, Parasitic kinetoplastids are difficult to control because organisms repeatedly

Change their protective coat

Euglenozoa, b. Parasitic kinetoplastids, They have an elaborate genetic mechanism for changing

Antigen on coat

Euglenozoa, b. Parasitic kinetoplastids, It is difficult to make a vaccine; other methods are used to control

Flies

SAR – Stramenopila, Stramenopila includes

Brown algae, diatoms, and oomycetes

SAR – Stramenopila, Stramenopila have very fine hairs on their

Flagella

Brown algae, Brown algae are conspicuous seaweeds of

Northern regions

Brown algae, Brown algae have a haplodiplontic life cycle involving

Alternation of generations

Brown algae, Sporophyte is

Multicellular and diploid

Brown algae, Gametophyte is

Multicellular and haploid

Brown algae, Brown algae are not

Plants

Diatoms, Diatoms are photosynthetic, unicellular organisms

Unique double shells made of silica

Diatoms, Some diatoms move using

Raphes

Diatoms, Raphes are

Two long grooves lined with vibrating fibrils

SAR – Alveolata, Alveolata includes

Dinoflagellates, apicomplexans, and ciliates

Alveolates, Alveolates have flattened vesicles called

Alveoli

Alveolates, Alveolates include

Dinoflagellates, apicomplexans, and ciliates

Dinoflagellates, Dinoflagellates are photosynthetic, unicellular with

Flagella

Dinoflagellates, Dinoflagellates live in

Aquatic environments

Dinoflagellates, Some dinoflagellates are

Luminescent

Dinoflagellates, "Red tide" are population explosions of

Dinoflagellates

Dinoflagellates, Fish, birds, and marine mammals may die from toxins produced by

Dinoflagellates

Apicomplexans, Apicomplexans include

Plasmodium

Apicomplexans, Apicomplexans are

Parasites

Apicomplexans, While feeding, a mosquito injects Plasmodium sporozoites into

Human

Toxoplasma gondii, Toxoplasma gondii invades epithelial cells of the

Human gut

Toxoplasma gondii, Toxoplasma gondii causes infections in humans with

Immunosuppression

Toxoplasma gondii, Toxoplasma gondii can cross the placental barrier to

Harm fetus

Ciliates, Ciliates are

Unicellular

Ciliates, Ciliates move using

Cilia

Ciliates, Ciliates have two nuclei

a macronucleus and a

Ciliates, Ciliates reproduce by binary fission and sometimes by

Conjugation

Conjugation, Only different mating types can

Conjugate

SAR – Rhizaria, Rhizaria use pseudopods for

Locomotion

Radiolarians, Radiolarians have glassy exoskeletons made of

Silica

Radiolarians, Radiolarians have needlelike

Pseudopods

Archaeplastida, This group consists of

Rhodophyta, Chlorophyta, Charophytes, and land plants

Archaeplastida, These photosynthetic organisms acquired their chloroplast through

Primary endosymbiosis

Rhodophyta - Red algae, Red algae are

Multicellular

Rhodophyta - Red algae, Red algae contain chlorophyll a and

Phycobilins

Rhodophyta - Red algae, Red algae are common in

Warm marine waters

Green Algae, Green algae consist of 2 lineages

Chlorophyta and Charophytes

Green Algae, Chlorophyta have unusual diversity and lines of

Specialization

Green Algae, Charophytes gave rise to the

Land plants

Charophytes – life cycle, Charophytes have a life cycle involving

Alternation of generations

Cell specialization in colonial chlorophytes, Multicellularity arose many times in the

Eukaryotes

Cell specialization in colonial chlorophytes, Colonial chlorophytes are examples of

Cellular specialization

Cell specialization in colonial chlorophytes, Volvox is a hollow sphere made up of a single layer of

500 to 60,000 individual cells

Haplodiplontic life cycles in multicellular chlorophytes, Some multicellular chlorophytes have

Haplodiplontic life cycles

Charophytes 1, Charophytes are also green algae distinguished from chlorophytes by their phylogenetic relationship to

Land plants

Amoebozoa 1, Amoebozoa includes

Amoeba, plasmodial slime molds

Amoeba, Most amoeba are

Free living

Amoeba, Amoeba are found in the soil as well as

Freshwater

Amoeba, Some amoeba are

Parasitic

Amoeba, Acanthamoeba enters the body through a wound and crosses the blood-brain barrier into the brain, causing

Inflammation and death