PRELIM 1 Flashcards
Lagerstätten
storage - place
- fossil sites where there is exceptional preservation; numerous + well preserved fossils
Burgess Shale
- famous Lagerstatten from the Cambrian
Absolute dating
radioactive decay to get age:
- after 1 half-life; 50 % daughter, 50% parent
- 2 half-life: 75% daughter, 25% parent
-3 : 87.5 daughter, 12.5 parent
*can only date igneous rock b/c daughter isotope is at 0% in molten rock
Relative dating
dating a layer relative to other dates
Geological time scale
- age of earth: 4.6 bya
- 1st life: 3.7 bya
- Cambrian explosion : 540 mya
- End of paleozoic: 250 mya
- end of mesozoic/start cenozoic: 65 mya
- anthropocene: 10 kya
dates found w radioacarbon dating
Superposition
the youngest layers are the ones laying on top
Lateral continuity
layers continue laterally over distances
- each layer is deposited at the same time & is the same layer even if eroded
Original horizontality
layers are deposited horizontally and maybe be deformed later
- movement of continental plates
- layers that are vertical/non-horizontal were originally horizontal
Cross-cutting
geological layers/ intrusions that cut across other layers are younger than layers that its crossing
Index fossils
- fossils in a distinct rock layer/short lived
- geographically widespread to help identify layers in different locations
can be used for stratigraphic correlation
Carbon dating
effective range 100 - 100k
5,730 yr half-life
Uranium lead dating
- effective dating range 10 million - 4.6 billion?
K- Ar dating
half life 1.3 billion yrs
- effective for 100k - 4.6 billion years
Precambrian & phenazoic era
Phanerozoic
all of the eras starting from the cambrian on
Fossils
remains, traces, impressions of once living organisms
most fossils are found in sedimentary rocks
Conditions that impede fossilization
- predators and scavengers
- bacterial decay
- dissolution in water
- physical disturbance
Conditions that promote fossilization
- rapid burial:
- protection from physical disturbance
- anaerobic environments
sedimentary rocks
formed from deposition of sediments falling to the bottom of body of water
what gets preserved
- teeth, bone, and chitinous exoskeletons or calcium carbonate shells
- plants: seeds, pollen, leaves, wood, rarely flowers
- bacteria, microbial mats; stromatolites formed from biofilms of cyanobacteria that trap sediment
types of preservation
- skeletal + other body elements are the most informative
- per mineralization/petrification: minerals are deposited in tiny holes within bones or wood, replacing organism and making stone structure
- impression fossils: made from a carbonaceous film imprint
phylogeny
cladogram: shows branching order and topology only
phylogram: branch lengths reflect the amount of evolutionary change
chronogram: cladogram where branch lengths are calibrated to real time
monophyletic
a clade: organism and all its descendants
clade
an organism and all its descendants
- most recent common ancestor to all the taxa
paraphyletic
an ancestor and a group of taxa but not all of its descendants are included
outgroup
has no shared traits with other taxa - represents the ancestral state
character state (ancestral, derived)
ancestral state:
derived state:
homoplasy
when similar characteristics are not due to common ancestry
convergent evolution
contribute to homoplasy
evolutionary reversal
DNA reversal? that contribute to homoplasy
vestigial
molecular clocks ?
index case
transmits the disease to a few other recipients
LUCA traits
- dna/rna
- mechanism to replicate dna
- shared biochem pathways / ATP
- codons for amino acids
- plasma membrane
- unicellular
Viruses
- no membrane bound nucleus
- lack mitochondria
- parasites
- lack ATP and molecular machinery for replication
model organisms
- e. coli
- arabidopsis thaliana
- saccharomyces cerevisae
- drosophila melanogaster
- mus musculus/ mice
- c. elegans
prokaryotes
unicellular, bacteria + archaea. not a monophyly
- reproduce by binary fission not mitosis
- capable of forming biofilms
Examples: staphylococcus, bacillus anthrax, cyanobacteria, ( lyme disease, chlamydia), e. coli, yersinia pests, vibrio cholerae, salmonella, archaea, halophile archaea
archaea
- no membrane bound nucleus or organelles
- ether linked lipids in membrane
- no peptidoglycan in cell walls
- extremophiles: ex, methanogen found in deep sea hypothermal vents
- halophiles
stromatolites
rocks that formed from biofilms of cyanobacteria trapping layers of sediment
- oldest stromatolites found in Greenland, dated 3.7 by a
eukarya
- membrane bound organelles
- all eukarya have mitochondria
proteobacteria organisms
e. coli, vibrio cholera, salmonella, yersinia pestis(bubonic plague)
- mitochondria via endosymbiosis
bacteria
- peptidoglycan in cell walls
- gram positive have more peptidoglycan
- gram neg. less
binary fission
DNA is replicated and parent cell is divided into two identical daughter cells.
horizontal gene transfer
exchange of genetic material between prokaryotes without reproduction
example: bacterial strain can transfer antibiotic resistance to other strains to fight a medicine
cocci
bacilli
spirilla
round, spherical
rod shaped bacteria
- bacillus anthracis
spiral, filaments that run along long axis
- ex; lyme disease, syphilis
cyanobacteria
photoautotroph - photosynthesize to make glucose
- were absorbed by endosymbiosis: chloroplast
spirochetes
chlamydia
sister taxa
- spiral shaped, Lyme Disease (?)
- chalmydia = STD, obligate parasites
eukaryote evolution
- loss of firm cell wall/flexible membrane for larger cells
- infolding to inc SA:V
- cytoskeleton - microtubules
- internal membranes with ribosomes
- infolding also = creation of nucleus
- flagellum
- mitochondria & chloroplasts
primary endosymbiosis
incomplete phagocytosis of a bacterium
- primary = phagocytosis of cyanobacteria/proteobacteria
- endosymbionts for mutualistic relationship w host
chloroplasts
- synapomorphy for all plants
- green algae, red algae, glaucophytes,
land plants
- green algae, red algae, glaucophytes,
some eukaryotes absorbed another one that had a chloroplast; secondary endosymbiosis
- single event of primary endosymbiosis is the synapomorphy for plants
Euglenids
- secondary endosymbiosis of green algae
- “protist”
Secondary endosymbiosis of red algae?
ancestor of stramenophile and ciliates
dinoflagellates
tertiary endosymbiosis of a ‘protist’ that had secondary endosymbiosis
“protists”
- not a monophyly
- Eukarya that aren’t animal, fungi, plants
- alveolates, stramenopiles, excavates, amoebozoans, opistokonts
Alveolates
dinoflagellates, ciliates, paramecium, plasmodium (carries malaria)
- unicellular with sacs (alveoli) beneath cell membrane
- secondary endosymbiosis; red algae
ciliates
alveolates, paramecium
- unicellular
- covered in cilia aka short flagella to move
dinoflagellates
alveolates
- 2 flagella; equatorial and longitudinal groove
- tertiary endosymbiosis
- are endosymbionts of coral (coral = quaternary endosymbiosis)
- source of red tide blooms
- flow-agitated bioluminescence
plasmodium
alveolate, malaria
- unicellular parasites
- vestigial chloroplasts
- complex of proteins at apical prominence used to attach and penetrate host
stramenopile
- 2 unequal flagella; one has tubular hairs
- brown algae, diatoms
- secondary endosymbiosis of red algae
brown algae
stramenopiles
- large multicellular
- secondary endosymbiosis of red algae
diatoms
stramenopiles
- secondary endosymbiosis of red algae
- unicellular
- secondarily lost double flagella
deposit silica in their cell membranes
excavates
euglenids, Giardia, Trypanosoma
- reduced or lost mitochondria
giardia
excavates
- intestinal parasite
- degenerate mitochondria; energy from host
euglenids
excavate
- mitochondria and a single flagellum
- chloroplast through secondary of green algae
trypanosoma
excavate
- free living/parasite
- single/large mitochondria
- sleeping sickness, chagas disease, leishmaniasis
amoebazoans
amoeba, slime molds
- lobe-shaped pseudopods
- move via cytoplasmic streaming
- unicellular
mitochondria
- double membrane; original from proteobacteria, second from invagination
- own circular DNA
glaucophytes
retain peptidoglycan in cell wall of chloroplasts from initial cyanobacteria
- unicellular
- reproduce asexually
red algae
uni or multicellular
- photosynthesize short wavelength/red pigment
- chlorophyll a
- lack peptidoglycan
green plants
“green algae” + land plants
- chlorophyll b and starch
- chlorophyll b = more range of wavelengths to be able to absorbed
“green algae”
sister to land plants
land plants
protected embryos and waxy cuticle
alternation of generations
occurs in all land plants
- sporophyte = diploid; gametophyte = haploid
diploid zygote –> multicell. diploid sporophyte –(meiosis)–> haploid spores –> multicell. haploid gametophyte –> mature to haploid gametes = sperm & egg
- two haploid gametes fuse through fertilization to produce diploid zygote again
non-vascular plants
mosses, liverworts, hornworts
dominant gametophyte generation
sporophyte is dependent on gametophyte for nutrition
moss/non-vascular life-cycle
dom. generation = gametophyte
sperm reaches female gamete by swimming in water
zygote –> diploid sporophyte (sporophyte nutritionally dependent) –> produces spores –> spores dispersed by wind
vascular plants
fern + lycophytes + seed plants
sporophytes (diploid) dominant
vascular tissue: xylem + phloem
seed plants
gymno- + angiosperms
in angiosperms; seed is surrounded by an ovary that ripens into fruit
seed plant life-cycle
female spore –> female gametophyte which produces egg –> structure w/ egg + fem. gametophyte = ovule
ovule attached to sporophyte cone
male spores –> male gametophyte = pollen grain–> pollen tube to deliver sperm to egg
fertilization happens inside ovule
fertilization/angiosperms
fertilize ovules inside ovaries
- male gametophyte grows pollen tube to reach the egg inside ovule inside ovary; seeds are enclosed and mature inside ovary
double fertilization
- one sperm fertilizes the egg
- second sperm fuses w two nuclei to form endosperm tissue that feeds nutrition
challenges faced by land transition
- desiccation = cuticle
- physical support
-mvt of fluids/nutrients = vascular tissue - protection of gametes/embryo = seed
- inc uv radiation = chlorophyll b
opisthokonts
fungi, choanaflagellates, and animals united by single posterior flagellum
MRCA fungi & animals
was unicellular and had a single posterior flagellum
- present groups have lost flagellum or its only present in certain stages (e.g sperm and chytrid fungal spore)
fungi
synapomorphy = chitin in cell wall and absorptive heterotrophy
- hyphae (mass of hyphae = mycelium) from fungus body and allows organic material/organelle exchange
carry out external digestion
absorptive heterotrophy
secrete enzyme which digest organism materials and nutrients can be absorbed into hyphae
- saprophages = feed on dead matter (decomposer)
- others may be parasitic
microsporidia
- reduced mitochondria, polar tube
- small, unicellular parasites, infect via polar tube
- pathogens
“chytrids”
- flagellated gametes used to swim in water
- amphibian killer fungus
- saprobic
arbuscular mycorrhizae
- form mycorrhizae with plants
- mutualistic. relationship; fungus get photosynthate and plant gets inc. surface area for soil nutrient acquisition
dikarya
ascomyota and basidiomycota
fungi and club fungi
- unique stage in sexual reproduction and they have septate hyphae
- part of its life-cycle has 2+ nuclei; genetic distinction between 2+ mating types (?)
- hyphae divided into compartments by the septa meaning they can control cytoplasm, organelle, and nutrient movement
ascomycota
- produce spores in the ascus
- sac or cup fungi
spores released from the ascus as the tip of the ascus bursts under pressure
morels, truffles, yeasts, molds and lichens
yeasts
important taxa: saccharmoyces cerevisae = model organism; brewer’s yeast
lichens
symbiont with a fungus + green algae +/or cyanobacterium living together
basidiomycota
spores produced externally on a basidium
- this looks like a club = club fungi
- spores are released passively by falling off
rusts, smuts, mushrooms, brackets
rusts and smuts = pathogens of plants
brackets = on sides of live or dead trees
