What are the 2 key ideas to taxonomy?
- Binomial nomenclature (Genus species)
- Hierarchy (Kingdom, phylum, class, order, family, genus, species)
Which domains are most closely related?
eukarya and archaea
what it the root of the phylogenetic tree?
the common ancestor
what do nodes represent on the phylogenetic tree?
nodes are splits where 2 groups separate
what is a clade on a phylogenetic tree?
a group of groups that includes the nodes of all the individual groups
what is an outgroup on a phylogenetic tree?
one group that is the least related to and not included in the clade
what is a sister group on the phylogenetic tree?
2 or more closely related groups that have to be in the same "generation"
what is homology?
shared ancestry, arose from the same origin
what is analogy?
similarity in function due to common environment
what is a monophyletic group?
includes the ancestor and all of the descendants
what is a paraphyletic group?
include a common ancestor but not necessarily all of the descendants
what is a polyphyletic group?
contains a descendant that doesn't belong because the common ancestor has not been traced back far enough
what is a derived trait?
trait shared by the group but not found in their ancestor
what is synapomorphy?
derived trait shared by group used as evidence of common ancestry
what are the steps to make a eukaryote from a prokaryote?
- 1. lose cell wall
- 2. unfold membrane and increase surface area
- 3. form cytoskeleton
- 4. form vacuoles by pinching of membrane
- 5. DNA and ribosomes already attached to membrane; more infolding until they're surrounded into the nucleus and ER
- 6. microtubules from cytoskeleton form flagellum
- 7. form mitochondriaa through endosymbiosis with proteobacterium
- 8. "optional" form chloroplasts through endosymbiosis with cyanobacterium
What is endosymbiosis?
- "internal and living together"
- one cell "swallows" a prokaryote but end up living together instead of being digested
- after living together for a long time, the genome of the endosymbiont becomes very reduced and may move to the nuclear genome
what is evidence of endosymbiosis?
- double cell membrane around mitochondria
- genes in mitochondria that match bacterial genes
- mitochondria and chloroplasts reproduce by binary fission independent of cell
what is the main feature of the protist group?
- nothing specific, it's a term used out of convenience, not a real taxonomic group
- they are eukaryotes that are not plants, fungi, or animals
what are unikonts?
- "single cone" protists
- referring to single flagella (if present)
- synapomorphy of opisthokonts: posterior flagellum (as in animal sperm)
- 2 featured groups (amoebozoans) - amoebas (loboseans) and slime molds
what are amoebas?
- unicellular, unikonts
- move via pseudopods and cytoplasmic streaming
- may have "test" or hard shell
- eat via phagocytosis
- some pathogenic (amoebic dysentery - 3rd leading cause of death from parasites)
what are slime molds?
- most closely related to amoebas
- move by cytoplasmic streamins
- eat via phagocytosis
- form large aggregates
- reproduce via "fruiting bodies" and spores
what are rhizaria?
- protists that typically have long thin pseudopods as compared to amoebas
- 2 featured groups - foraminiferans and radiolarians
what are foraminiferans?
- rhizaria that are primarily marine
- secrete CaCO3 test - formed major limestone deposits in ocean
- pseudopods stick out of test - capture prey, locomotion in some
what are radiolarians?
- rhizaria that have thin, stiff pseudopods stick out of test - assist in floating, increase surface area
- SiO2 tests - very ornate and unique, used as fossil markers
- marine zooplankton
what are excavates?
- protists once grouped together because some lack mitochondria
- 2 featured groups - diplomonads and parabasalids (metamonads)
what are metamonads?
- unicellular excavates
- no mitochondria, anaerobic
- originally thought "primitive"
- now known to have been lost (evolutionary reversal - had mitochondrial DNA in nucleus)
- symbionts (mutualistic and parasitic)
- examples: giardia (causes "beaver fever"), trichomonas (causes STD in humans) mutualistic symbiont in gut of termites digesting wood
What are plantae?
- common ancestor was where single endosymbiosis event of a cyanobacterium occurred
- glaucophytes - contain small amount of peptidoglycan on inside and outside of chloroplast membrane, same as cyanobacteria
- 2 featured groups - red and green algae
what are green algae?
- also called chlorophytes
- photoautotrophic plantae
- diverse morphology - unicellular, colonial, multicellular filaments, multicellular sheets
- freshwater, marine, terrestrial
what are red algae?
- multicellular, marine (most tropical)
- accessory pigment - color, ability to use different light wavelengths
- souce of agar
- some secrete CaCO3 - "coralline algae"
what are chromalveolates?
- usually have cellulose in their cell walls
- alveolates have sacs (aveoli) just below their plasma membrane
- stramenophiles, most have 2 flagella, one with hairs
what are apicomplexans?
- obligate animal parasites
- complex life cycles involving multiple hosts
- non-functional chloroplasts
- cause of malaria (#1 infectious disease, affects red blood cells, transmitted by mosquitoes)
what are dinoflagellates?
- some cause "red tide"
- release neurotoxins
- "paralytic shellfish poisoning"
- vertebrates most affected due to bioaccumulation
what are brown algae?
- multicelluar, large
- marine, temperate, coastal
- grow very quickly
- form kelp forests - extremely important habitat for may animals
- produce alginic acid - anchor to rocks
- gas bladders at base of blades provide buoyancy
What are diatoms?
- very important part of the phytoplankton
- cell walls of SiO2
- widely used in paleolimnology
- source of "diatomacous earth"
- toothpaste, metal polishes, pool filters