Life Sciences Exam 2

protists

more structural and functional diversity than all other euk clades, most are unicellular, complex anatomy with organelles in single cells,

plastid origins via endosymbiosis

primary and secondary endosymbiosis (two different ways of evolution)

primary endosymbiosis

eukaryote engulfs a bacterium

primary endosymbiosis example

heterotrophic eukaryote engulfing cyanobacteria to create plastid lineages, bacterium engulfed by archaean cell to create mitochondria

secondary endosymbiosis

a eukaryotic cell engulfs another eukaryotic cell which has already undergone primary endosymbiosis

secondary endosymbiosis example

red or green algae being engulfed by a eukaryote

excavata clade

cytoskeleton, some have an excavated feeding groove, uncludes modified mitochondria, unique flagella

organisms in excavata

diplomonads, parabasilids, euglenids

diplomonads

reduced mitochondria (mitosomes), live in anaerobic environments and get energy via biomechanical pathways, have two nuclei, multiple flagella, often parasites

giardia intestinalis

diplomonad, global, found in water, most common infection of intestines, deadly in kids (dehydration)

parabasilids

reduced mitochondria (hydrogenosomes-derive some energy anaerobically)

trichomonas vaginalis

causes yeast infections, parabasilid

euglenozoans

includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, parasites, have a spiral, crystal rod within flagella, includes kinetoplastids and euglenids

kinetoplastids

type of euglenozoan, trypanosomes, cause sleeping sickness in aftrica and chagas disease in america

euglenids

mixotrophic, can change morphology while moving, no cell wall, contractile vacuole, very motile, have a pellicle (saw them in lab)

sar clade

stramenopiles, includes diatoms, brown algae, golden algae, most have two flagella-one hairy and one smooth

diatoms

important in global carbon cycle, a major component of marine phytoplankton, unique, two part cell wall made of silicon dioxide

golden algae

named for their unique color which comes from different pigments that mask chlorophylls, mostly biflagellate, all primary producers, some mixotrophs, mostly unicellular but some are colonial

dinobryon

golden algae, colonial, freshwater

brown algae

most common algae, multicellular, “seaweed,” contain a holdfast, stipe, and blades

giant kelps

brown algae example

alternation of generations

seen in some multicellular algae and most plants, alternating between multicellular forms of haploid and diploid structures

prokaryotic benefits to humans

biological treatment of wastewater, recover metal from ores, synthesis of vitamins, production of antibiotics and hormones

bacterial ecological functions

nitrogen fixation

eutrophication

excess n and p sent to surface of water, leads to cyanobacteria blooms, cause bad water quality and eventually ead to anoxic conditions (low o2 levels kills fish)

biotech uses of prokaryotes

bioremediation (clean up oil spills, plastic degradation), bioplastic synthesis, crispr

nitrogen fixation

the conversion of n2 into biologically available forms of nitrogen

transduction

phage infects bacteria, its dna gets packaged into new virus, transferred after cell lysis to a new host

conjugation

process where genetic material from one cell is sent to another via a sex pilus

conjugation example

f plasmid in e coli

transformation

cells pick up dna from their surroundings and encorporate it into their genome

three types of horizontal gene transfer

conjugation, transduction, transformation

evidence of rapid prokaryotic evolution

richard lenski (msu) tested e coli’s adaption to a new environment, found that they can evolve rapidly to adapt to a new environment

genetic recombination

combining of dna from two different sources

protocells

early protocells with self replicating catalytic rna were more efficient therefore increased in number, ribozymes allowed for replication, implies that early life was ikely an “rna world” and that rna could have provided the template for making dna

ribozymes

ribonucleic acid enzymes, a catalytic form of rna

history of life on earth

4 bya-isotopic evidence of life signatures, 3.5 bya- stromatolites, cyanobacterial mats

problems with fossil records

hard to find places where fossils form, favors hard skeletons/shells (no bacteria), favor organisms that existed for a long time, common species fossilized more, widespread distribution

current atmosphere composition

n2-79, o2-20-21, ar- less than 1, co2-430 ppm (plus h20)

first oxygen revolution

2.3 bya, prokaryotes (specifically cyanobacteria), then unicellular eukarya

second oxygen revolution

800 mya, evolution of plants (marine and terrestrial)

cambrian explosion

540-525 mya, lots of vertebrae and new diversity, includes chordae (fish)

permian extinction

251 mya, volcanism increased co2, lead to ocean acidification, boundary between paleozoic and mesozoic ages

asteroid at mexico

boundary between mesozoic and cenozoic, caused great extinction

extinction rates

increase with temperature increases

sixth great extinction

right now

prokaryotes

found in all major habitats, huge genetic diversity, most are unicellular, no membrane bound organelles

cocci

spherek, 1 um

bacilli

1 um, oval

spirelli

long squiggle, 3 um

strata/stratigophy

relative ages only in geologic layers of “older” and “newer” sedimentary rock

radioisotopes

used for absolute dating and aging of rocks and fossils

endosymbiotic theory

lynn margulis et al, mitochondria and other plastids were put together like independent prokaryotic cells and that eukaryotic organelles were previously free living prokaryotic organisms

serial endosymbioses

eukarya developed via multiple endosymbioses, including dna and reproduction in bacteria and mitochondria

gram positive

thick wall of peptidoglycan

gram negative

thin wall of peptidoglycan and covered by a layer of lipopolysaccharides (often toxic)

bacterial features

endospores, capsules, fimbrae

archaea cell walls

lack peptidoglycan

peptidoglycan

a network of sugar polymers with polypeptides linking them

bacterial motility

prokaryotic flagellum, chemotaxis

positive taxis

movement toward stimulus

negative taxis

movement away from stimulus

photoautotroph

energy source is light, carbon source is co2 or hco3c

chemoautotroph

energy source is inorgamic chemicals, carbon source is co2 or hco3

photoheterotroph

energy source is light, carbon source is organic compounds

chemoheterotroph

energy source and carbon source is organic compounds