Bio 242 Diversity of Life Semester Notes
Bio 242 Diversity of Life Semester Notes Bio 242
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Date Created: 05/04/16
• Diversity of Life • evolution=framework ‣ change in organisms over time ‣ common ancestry- hands down heritable characteristics ‣ changes in allele frequency in a gene pool over time ‣ adaptations- environmental speciﬁc • features that better assist an organism to live in its habitat • changes can mold a species to a particular environment mechanisms of evolution ‣ natural selection- differential survival & reproduction of members of a species,those with better traits survive and reproduce to pass on beneﬁcial heritable traits • not a random process- acts upon characteristics that are already present • genetic drift- random changes in allele freq that have nothing to do genetic ﬁtness • gene ﬂow- introduction/movement of new alleles for the same characteristic or trait from one population to another ~ mixing of populations ex) ladybugs w/ 3 spots on wings mix w/ ladybugs w/ 2 spots on their wings • mutations- random/spontaneous changes in DNA sequence for a particular gene • sexual reproduction- increases variation in changing combinations for different traits happens when genetic material is exchanged and rearranged • Speciation ancestral population- original population population splintering- population splits for one reason or another,two populations are formed from one,and members of each population do not interbreed gene ﬂow inhibited- dont reproduce due to habitual isolation genetic divergence- each population experiences changes in its population due to the environment they are in ‣ living in different environments can cause different adaptations,which eventually can cause them to become 2 diff species reproductive isolation- can no longer interbreed due to mechanical/gametic isolation • extant population- population branched from the original population • how to make sense of organismal diversity taxonomy & classiﬁcation ‣ linneaus- developed binomial naming format (genus(capitalized) followed by speciﬁc epithet of the animal[all italicized]) & universal system...can't use common names in science Domain- Kingdom- Phylum- Class- Order- Family- Genus- Species ‣ domains:bacteria,Archaea,Eukarya systematics- individuals that gather any type of information about a species to be used to classify an organism phylogeny- evolutionary history of an organism or taxon(group) ‣ goal:produce a correct evolutionary history cladistics- science that uses the information from systematics (data) in order to construct evolutionary history (relation of one species to another) ‣ "clade" --> includes common ancestor and all its descendants • starts with order,then breaks down into order,family,genus,and species from there • phylogenetic trees line on left represents the beginning/root of ancestral pop branch points represent divergence of the population before ‣ multiple branch points in each tree ‣ when there are three that come from one branch point,it forms a polytomy,which is an unresolved pattern of divergence ‣ when there are two on the right side from a branch,the two resulting taxons are called sister taxons ‣ when a taxon is branched directly from the ancestral population,it is called a basal taxon (outgroup) (helps root ancestry of other species) • Phylogeny natural system that reﬂects ‣ evolutionary relationships ‣ less emphasis on ranking ‣ common ancestry ‣ homologous characters- characteristics that are heritable and come from the common ancestor • can be morphological behavioral biochemical molecular ‣ proteins (AA sequences) ‣ nucleotide sequences analogous character- homoplasis- are unacceptable in phylogenies ‣ develop from convergent evolution- similar traits develop in unrelated organism that live in similar environments due to independent events difﬁculties w/ phylogenetic relationships ‣ recognizing • homologies • analogies (homoplasies) • evolutionary reversals- revert back to an earlier adaptation in the lineage,like regressing to leglessness after developing them can look at it on the dna level ‣ sequence changes can change parts of the sequence,while part of it remains the same ‣ computer programs exist that can ﬁnd homologies in dna sequences • can insert blanks into sequences where insertions/deletions may have occured to show the homology between the 2 or more sequences • linking classiﬁcation & phylogeny done by forming clades...true clades: ‣ using common ancestry ‣ monophyletic- single common ancestor and all its descendants • can tell if it is one bc only need one snip ‣ can be referred to as hypothesis because it is subject to change • ex) new genetic evidence has comlpetely changed the idea of the ﬁrst species to branch from single celled organisms...sponges no longer ﬁrst paraphyletic grouping- not true clade... ‣ old group that is no longer valid ‣ includes some but not all the descendants ‣ needs more than one snip • ex) birds must be included in reptile order polyphyletic grouping ‣ grouping of organisms that have no common ancestor ‣ ex) not all insect eating plants have a common ancestor • Which characters are appropriate to consider when making monophyletic groups? homologies symplesiomorphy(shared by 2 or more groups) (plesiomorphy-ancestral state) ‣ shared ancestral character ‣ originated in ancestor of taxon synapomorphy(shared by 2 or more groups) (apomorphy-deﬁnes a clade) ‣ shared derived character ‣ not found in ancestors ‣ deﬁnes a clade parsimony ‣ simplest explanation ‣ best hypothesis • best ﬁts data • makes fewest assumptions ‣ fewest homoplasies,especially if complex • analogous features • convergent evolution • horizontal gene transfer • vertical gene transfer Prokaryotes:Domains Bacteria &Archaea (ch 24) small pervasive (can live almost anywhere on Earth..espArchaea) versatile (represent every type of metabolic pathway) essential (responsible for changing out atmosphere from co2 to o2..cycle nitrogen[needed for macromolecules...nucleic acids & proteins]) • General prokaryotic Characteristics unicellular no membrane bound organelles no nucleus- have "nucleoid region" no cytoskeleton reproduce by binary ﬁssion smaller ribosomes • most common prokaryotic shapes cocci- round bacilli- rod spirochetes- spaghetti like • cell wall protects & maintains shape bacterial:peptidoglycan ‣ gram positive- thick peptidoglycan layer ‣ gram negative- thin peptidoglycan layer with another membrane over top archael:other polysaccharides & proteins (no peptidoglycan) • cell surface structures capsule- external to cell wall.."hairy" layer ‣ formed of polysaccharide linked layers...sticky ‣ protective layer..can make it stick to host better(enhances pathogeny) ﬁmbriae- protenatious tubes that stick out from cell surface ‣ enhance adhesive ability ﬂagella- structure used for motility ‣ diff types developed independently • prokaryotes lack internal compartments but still carry out necessary processes some can make endospores- compacted genetic material surrounded with tough structure very resistant to attack • genomic organization single circular chromosome in nucleoid region ‣ not associated with histones,but there are other organizing proteins plasmids...carry continuancy genes..can offer antibiotic resistance...can be transferred from 1 species to another • reproduction binary ﬁssion origin of replication- where chromosome is duplicated cell wall is formed after information is duplicated ‣ cell wall begins to pinch in and informations splits into 2 cells • prokaryotic genetic diversity rapid reproduction mutation genetic recombination horizontal gene transfer ‣ transformation- can pick up foreign dna from dead cells ‣ transduction- when bacteriophages infect diff bacteria they transfer bacterial dna from one bacteria to another ‣ conjugation- when 2 bacteria get close enough they can exchange dna as hey approach each other • sex pilus allows this to happen (like a ﬁmbrea) • nutritional and metabolic modes energy source ‣ phototrophs:light • lights,co2 ‣ chemotrophs:organic or inorganic molecules • chemoheterotrophs:need organic carbon • chemoautotrophs:can oxidize inorganic compounds and get energy from them • photoheterotrophs:light,organic compunds carbon source ‣ autotrophs:co2 ‣ heterotrophs:organic mols • metabolic relationships to oxygen obligate aerobes.. use o2 faculative anaerobes..use anything available oblagate anaerobes...poisoned by o2 • nitrogen metabolism nitrogen ﬁxation ‣ convert n2 to nh3...can only be done by bacteria nitriﬁcation- conversion of nh3 to no2- and no3- • bacterial clades proteobacteria-gram-,form transfer to anima chlamydias- usually pathogenic?,gram- spirchetes- spiral shape,gram- gram+ bacteria- endospore formation cyanobacteria - imp in generation of chloroplasts • Archaea ("sister to Eukaryotes"..but morphologically similar to prok) ‣ shapes- have multiple diff ‣ ﬁrst came from extreme environments ‣ also found in mild environments ‣ most ecologically diverse ‣ no pathogenic form ➡Make comparison lists btwn prok,archaea,and euk⬅ ➡ see picture⬅ thermophiles- can survive at very extreme(high) temps halophiles- can survive in high salinity environments methanogens- combine c w/ h gas to form methane,which also produces energy (unique to archaea) ‣ anaerobic...poisoned by o2 ‣ usually found in swmapy,deep sea hydrothermal vents,or gastointestinal tracts of various organisms acidophiles- can live in very acidic environments psychrophiles- can live in extremely cold environments • Roles of prok(importance) nutrient cycling in ecosystems nitrogen ﬁxation ‣ also convert things like N,S into organic mols symbioses- w/ humans,cows,etc breaking down foodstuffs ‣ prok & plant...assist in N ﬁxation ‣ prok & fungi- lichens..can help w/ ecological succession could be pathogens.....small fraction bioremediation- cleaning up oil spills and things of that nature genetic engineering- put genetic instructions into them to get them to produce substances needed for other species,such as human Chapter 25:Origin & diversiﬁcation of eukaryotes • evolution of euk cells & multicellularity • Domain Eukarya KingdomsAnimalia,Planta,Fungi,and various "protist" kingdoms • currently organized into 4 supergroups (clades) of euk organisms • phylogeny in dynamic state (can change) includes all multicellular organisms except the large ones (animals,plants, fungi) archaeplastida,stramenopiles (part of SAR groups),opisthokonts <-- important groups • evolution of euk(means true nucleus) cells prok are ancestors ~3.5 bil yrs ago-1.8 bil yrs ago (fossil evidence) ‣ gradual process organisms we're familiar with have developed since about 600 million yrs ago • endosymbiosis theory- 1 organism living in another engulfed aerobic bacteria..allowed more efﬁciency of energy ‣ probably the ancestor of cyanobacteria ‣ heterotrophic euk w/ mitochondria preceded development of photosynthetic euk w/chloroplasts ➡see picture⬅ • origins of multicellularity colonial forms- groups/clusters of same types of cells that are held together how are cells held together? ‣ ECM • shared cell walls • connecting proteins true multcellularity ‣ likely happened in multiple indep events ‣ red,green,and brown algae ‣ plants,animals,fungi • volvox seems to be ﬁrst rearrangement and coopting of existing genes Dna sequence data support that choanoﬂagellates are ~sister to all animals • evolution of animal multicellularity chaonoﬂagellates ‣ morphological homologies ‣ dna seq homologies homologous protein domains ‣ cell adhesion proteins • cadherin large family of ECM proteins ‣ cell to cell signaling comparison showed that choanoﬂagellate cadherin-like protein & animal cadherin domains .....dont need lots of genetic changes ~~~~ chapter 10 • life cycle diversity asexual- simple..produces clones...rep of dna then cell splitting sexual- exchange/recombination of genetic info from 2 diff individuals ‣ gametic life cycle ‣ zygotic life cycle...multicellular haploid individual...mitosis produces gametes in these individuals (fungi)...zygote is only representative of diploid state in fungi,then meiosis occurs to produce fungal elements(sexual spores) ‣ sporic life cycle...diploid form is sporophyte..plants and some algae... alternation of multicellular generations...fertilization produces zygote, mitosis produces haploid gametophyte... • mitosis/meiosis...diploid/haploid..etc • terms for sexual lifecycles spores gametes gametic life cycle zygotic llife cycle sporic life cycle ‣ sporophyte ‣ gametophyte ‣ heteromorphic(diff) or ospmorphic(look same) -brown algae are in SAR clade -all subgroups inArchaeplastida • pg in ch 25..evidence supporting endosymbiont theory..(look up) own dna own membrane (dbl membrane) ribosomes make own proteins • do study questions on bb • create timeline for evolution of diff organisms earth..4.5 bil yrs ago ago life..3.5bil yrs 1st euk fossil evidence..1.8 bil yrs euk multicellular organisms..1.2 bil multicellular colonial euk..800 mil large multicellular euk...600 mil land animals start to develop...470 mil...plant/fungi like organisms preceded animals on land • charophytes- brown algae • chlorophytes- green algae • SAR-stramenopiles(placement of ﬂagella)- brown algae characteristics: ‣ chlorophyll a(allows organisms to undergoe photosynth that releases o2 after splitting water..absorbs red & blue pigments) & c(absorbance slightly diff than a..absorbs light chlorophyll a cant) ‣ carotenoids (fucoxanthin...yellowish-brownish pigment..allows absorption of wavelengths diff than a & c) ‣ laminarin- deﬁnes clade..storage carbohydrate (instead of starch in land plants) ‣ cell wall contains.. • cellulose- common • alginic acid- clade deﬁner ‣ largest type of algae ‣ parts..exs: • blades..leaf like..photosynth • stipe...stem like...support and getting it closer to light • holdfast...attached to stipe..secretes enzyme that attaches them ﬁrmly to whatever they're on ‣ ...kelps(giant seaweeds)..very large..live in deep parts of ocean ‣ heteromorphic alternation of generations(look diff)..diploid sporophyte is main stage..give rise to sexual ﬂagellated haploid spores by meiois...produces gametes by mitosis • Archaeplastida red algae- ‣ chlorophylls a & d ‣ contain phycoerythrin- red pigment...overpowers chlorophyll presence...can exist in very deep waters (absorbs blue wavelengths..which penetrate farthest into water) ‣ ﬂoridean starch & mannitol ‣ cell wall: • cellulose • agar..can be used to culture microorganisms • carageenan..used in processed foods to suspend things green algae ‣ chlorophylls a & b ‣ carotenoids (carotene & xanthyophyll...absorb blue & green pigments) ‣ call wall:cellulose ‣ starch ‣ alternations of isomorphic generations(look same) (celetic?)..variation of sporic life cycle...sporophyte is diploid..some cells in sporophyte undergo meiosis and grew mitotically to produce haploid gametophytes(which look morphologically identical to sporophyte).. gametes fuse to produce zygote,which divides mitotically to give rise to new sporophyte generation • green algae and land plant similarities photosynthetic,chl a,chl b,carotenoids euk & multicellular autotrophs cellulose in cell walls;starch for storage reproduction ‣ plants:sporic meiosis only ‣ algae:all forms of meiosis observed reproductive structures ‣ complex multicellular organs in plants (special organs producing spores or gametes) ‣ simpler structures in algae Chapter 26 • Adaptation of plants to land • relationships among multicellular euks fungi & animals are sisters charophyte algae(special subgroup of green algae) and land plants(~embryophytes) are sisters algae is a paraphyletic grouping • charophyte algae (closest algal relatives of plants...sister taxa) homologies w/land plants ‣ rosette complexes in the plasma membrane..small cirlce completes that help link the glucose to form cellulose (linear in other algae) ‣ sperm ultrastructure- placement of centrioles,ﬂagellum,etc ‣ nuclear & chloroplast genes....many homologies ‣ sporopollenin- protective polymer...helps prevent spores and pollen from drying out • covers zygotes of charophytes • covers spores and pollen of plants plant traits not in charophyte algae ‣ apical meristems...clusters of actively dividing cells that allow growth and organ formation..usually found at the tips of organs (ex,roots) ‣ sporangia that produce spores (always..always heteromorphic) • protected with sporopollenin ‣ multicellular embryos(formed by mitotic divisions...develops after a zygote) • dependent on gametophyte tissues • land plants are embryophytes • transition from aquatic to terrestrial (land) environments problems ‣ support ‣ decication (drying out) ‣ mineral acquisition solutions ‣ cuticle (waxy cutin...covers parts that touch air,reduces water loss) ‣ roots..anchorage,storage,transport of necessary substances ‣ stems..link photosynthetic leaves to root system ‣ leaves- large surface area for photosynth...gas exchange • stomates...allow entry of co2 and h20,can open close,prevent dehydration ‣ vascular tissues..aid in movement • xylem- absorbs water and dissolved minerals ligin- strengthens cell walls that make up xylem • phloem- moves carbohydrates • Plant groupings byrophytes/non-vascular plants(cant transfer ﬂuid inside) (470 mil yes ago) • exs:liverworts,mosses,hornworts ‣ "amphibia of plant kingdom"...very small,very dependent on water ‣ "carpet" forming... • thalloid or leafy..not real leaves • rhizoids..anchoring structures..very small ‣ sporic meiosis- alternation of generations • gametophyte (haploid) is main plain phase seen (larger than sporophyte) ‣ adaptations to land • stomates ‣ lifecycle of moss: • male produces sperm(need water) and swim to female gametophyte (has egg..archegonia..produce egg) anthroidia produce sperm.zygote undergoes mitotic divisions,and sporangium grows on top of gametophyte.haploid spores released and produce next gametophyte generation gametophyte - haploid ‣ larger and more persistent archegonia- contain an egg (haploid)..where sporophyte grows antheridia- produce swimming sperm(...gametophyte) fertilization happens in archegonia,but requires water goes thru mitotic divisions to produce a sporophyte(haploid) that is dependent on the gametophyte sporangia undergo mitosis to produce haploid spores (ephermeral generation..short lasting) • seedless vascular plants (425 mil) • ex) lycophyta(includes lower plants,but those higher than mosses ex: club moss contain conelike clusters that produce spores), monilophytes(ferm like...ex:ferns) ‣ increasing height ‣ vascular system ‣ lignin- polymer supporting cell walls,allows transport of nutrients ‣ true leaves,stems,and roots ‣ cuticle- waxy sub covering plant,prevents h2o loss ‣ stomates- pores that can open and close likely selected for due to ability to grow more vertically life cycle changes:...still sporic • larger,conspicuous sporophytes (2n) independent • smaller gametophyte (n) independent but ephemeral ‣ rhizome (underground stem that anchors fern frawns)...grow to form leaf like stx (sporophyte),sporangia undergo meiosis to produce haploid cells,sporangia cluster to form sorus(es),diploid cells in sporangia undergo meiosis to produce haploid spores,spores grow germinate into haploid gametophyte,archegonia and antheridia grow on gametophyte, gametophytes undergo mitosis,producing archegonia that have eggs,and antheridia form ﬂagellated sperm,meet water,fertilization happens in archegonia,forming zygote that grows into new sporophyte ‣ fern life cycle: • sporophyte (2n) • ﬁddlehead-frond • rhizome • sporangia- produce spores special cells undergo meiosis to produce haploid cells-> spores (n) • haploid spore germinates into haploid gametophyte • gametophyte produces archegonia(w/eggs) and antheridia(w/sperm) • zygote produced(2n) that forms into sporophyte leaf evolution ‣ ﬂat blades increase surface area ‣ two types of leaves: • microphylls- leaves w/single vein 410 mya lycophyta(seedless vascular) • megaphylls- leaves with a highly branched vascular system (all newer plants) 370 mil yrs ago monilohytes & seed plants • seed plants (305 mil) ‣ oldest fossils:360 mya ‣ earliest gymnosperm(cones) fossils:307 mya ‣ earliest angiosperm(ﬂowes) fossils:140 mya see diagram in pp reproductive adaptations of seed plants: ‣ greatly reduced gametophytes • develop on sporophyte generation megasporangia(ovule) microsporangia(pollen) ‣ ovules- female stx formed and retained on sporophyte..protects developing gametophytes and sporophytes ‣ pollen- immature male gametophyte.released for sexual reproduction ‣ seeds- can distribute next generation to another area in a protected stx • advantages: protection prevents desiccation dormancy aids dispersal • gymnosperms ("naked seed") released from parents w/out any casing other than seed coat sexual stxs are in cones/spikes layered with "scales" ‣ at bottom of megasporangia is ovule ‣ at bottom of male cone(microsporangia) is sporangium containing diploid cells that will undergo meiosis ovule development ‣ female cones- all tissues are 2n ‣ start small & grow large and woody • 1 to 2 yrs for seed development ‣ ovules located at base of cone scales • integument(2n)- forms seed coat • megasporangium (2n) • megasporocyte (2n) ‣ within the megasporangium (2n)..1 megasporocyte (2n) undergoes meiosis • 4 haploid cells produced,but 3 degenerate • net production:1 functional megaspore(n) grows by mitotic divisions into a gametophyte (still inside megasporangium) producing a female gametophyte w/ 1 or 2 archegonia gymnosperm pollen development ‣ male cones are papery and ephemeral ‣ microsporangia(2n) are sacs with diploid cells located at base of cone scales • each microsporophyte (2n) undergo meoiosis 4 microspores (n) each divide mitotically and gives rise to pollen grains,sprotected by sporopollenin • pollen grains are released from parent sporophyte cones immature male gametophyte dispersed by wind generative cell(divides once by mitosis and gives rise to 2 sperm nuclei) & tube cell(grows cellular stx into archegonia where egg is) ‣ pollenation- delivery of male gametophyte to receptive stx • not equivalent to fertilization • pollen grains sift through open scales of small female cones • fertilization takes place after pollination ‣ pollen grain germination:tube cell grows into pollen tube and grows through female gametophyte and into the ovule ‣ next,generative cells does through meiosis and one sperm moves into archegonium to egg seed development in gymnosperms ‣ integument-> seed coat (2n) ‣ female gametophyte (nutritive tissue)(2n) ‣ embryo (2n) reproductive synapomorphies • ovule ‣ contains a greatly reduced female gametophyte ‣ provides stx for seed formation • pollen ‣ greatly reduced male gametophyte • dispersed by wind/air sperm- haploid nucleus • fertilization does not require water • seeds pine life cycle..study..on pp • Angisperms (140mya) (most successful plant group) reproductive synapomorphies ‣ further reduction in gametophytes ‣ shortened seed development time ‣ ﬂower ( cluster of modiﬁed leaves that protect embryo) • coevolution with pollinators • attract and reward pollinators • double fertilization- seeds with triploid (3n) endosperm • fruit- coevolution w/ seed dispersers enhances seed dispersal • ﬂower parts...table on pp anther is microsporangium carpel is landing place for pollen pollen development ‣ anther(2n) is 4 fused microsporangia ‣ microsporophytes (n) ‣ get 4 microspores from meiosis fro microsporophytes ‣ 2 celled pollen grain(n) = male gametophyte • tube cell (n) • generative cell (n)- divides mitotically to produce 2 sperm nuclei • all protected by sporopollenin ovule development in ovary/carpel ‣ ovule= integument,megasporangium,megasporocyte (2n) ‣ megasporocyte-> meoisis ‣ 4 haploid cells,3 degenerate ‣ 1 functional megaspore (n) -> 3 mitotic divisions ‣ female gametophyte = 8 called embryo sac • 3 antipodal cells • 2 polar nuclei in central cell • 2 synergids • 1 egg pollination & dbl fertilization ‣ transfer of pollen...tube cell grown down carpel and forms pollen tube ‣ generative cell(n)-> 2 sperm nuclei ‣ dbl fertilization • sperm + egg= zygote • sperm + 2 polar nuclei - triploid endosperm (3n) serves as food source for sporophyte when seed germinates post fertilization in angiosperms ‣ ovules develop into seeds • integument --> seed coat • zygote --> embryo • endosperm--> nutritive tissue ‣ carpel(ovary) develops into fruit to aid in seed dispersal • ovary wall develops into pericarp diff ways angisperms have exploited to disperse seeds ‣ water- coconuts..endosperm and endocarp inside buoyant husk ‣ wind- winged/plumed ‣ animal- b abiotic- doesnt require organisms to spread pollen biotic- requires organisms " " " Test:chs.20,24,25,26,30(597-607) Chapter 26 • Fungi break down organic matter ‣ nutrient cycling essential for plant nutrition symbioses ‣ pathogenic ‣ beneﬁcial • fungi characteristics eukaryotic haploid (diploid stage is very brief..then creates haploid spores) heterotrophic (chemoheterotrophs..need ﬁxed carbon) ‣ absorptive- release enzymes that allow them to break down chemicals that are very hard to break down(live in their food) ‣ produce exoenzymes • extracellular digestion,then absorb the monomers • nutritional modes saprobes- decompose and live in dead plants & animals parasites- pathogenic to living plants and animals mutualistic symbionts- have fair trade w/ other organism ‣ mycorrhizae ‣ lichens • body structure mushroom cap- where sexual spores are produced unicellular- yeasts multicellular ﬁlaments ‣ underground or visible on surface (mold) ‣ hypha (hyphae) • types: septate- have small holes,each cell has single haploid nucleus..as it grows,nuclus divides and moves to growing tip,then cell wall forms btwn the newly made cells (derived feature) non-septate- ancestral feature...numerous haploid nuclei that are genetically identical..cells not separated by cell way..senositic? haustoria- hypoﬁlament makes projections into adjacent cells of another organism...makes hole in cell wall (of plant) and send a hyphae through it,and is there but does not hurt it ‣ mycelia- mass of hyphae glycogen- storage carbohydrate (like animals) chitin- in cell walls • reproduction asexually ‣ conidia- spores...can be formed in many ways... • tips of branches pinch off into spores ‣ budding- nuclei divide asymmetrically...cytoplasm divides (also asymm).. progeny are small,parent is bigger. sexual ‣ zygotic meiosis (lc)- haploid individual • secrete pheromones..two diff types(but same species) grow towards each other and grow together.. ‣ plasmogamy- hyphae(cytoplasm) fuse together ‣ heterokaryon- "different nuclei"..two diff types of nuclei uniting in same individual ‣ karyogamy- "nucleus marriage"..equivalent to fertilization..nuclei are the gametes..fuse to form zygote..goes thru meiosis and produced sexual spores ‣ spores..give rise to new fungal organisms • generalized fungal life cycle (on 26 PP) • 5 diff groups chytrids (basal group) ‣ in lakes and soils ‣ cell wall w/ chitin ‣ have ﬂagellated spores (zoospores) zygomycetes ‣ non-septate hyphae ‣ zygosporangia (fruiting body) (sexual spores) ‣ exs: • rhizopus stolonifer (black bread mold) • pilobolus glomeromycetes ‣ non-septate hyphae ‣ arbuscular endomycorrhizae (most common form of mycorrhizae relationships) • positive symbiotic relationships w/ plant roots (haustoria) • look like little trees • live inside plant cells gets ﬁxed C and water from the plant plant gets enhanced ability to take up nutrients (speciﬁcally P) ‣ enhances the surface area for nutrient uptake for plant and fungus ascomycetes ‣ septate hyphae ‣ complex sexual structures...produce elaborate fruiting bodies • ascocarp- fruiting body of ascomycetes ascospores...result of meiosis ‣ exs:fungi w/ mushroom/cuplike stxs/trufﬂes basidiomycetes(most derived fungal group) ‣ septate hyphae ‣ some species are ectomycorrhizae (form a sheath of mycelia around root tips)..usually seen with tree roots ‣ complex sexual stxs • basidiocarps- fruiting body...produces basidiospores from meiosis • basidia(clublike stx) forms with gills...contains basidia.. karyogamy(fertilzation) occurs in basidia...basidiospores form in "gills", then get dispersed..get 4 spores from each basidia ‣ exs:toad stool,shelf fungi,puffballs • dikaryotic- two haploid nuclei ..but still heterokaryon • lichens- beneﬁcial symbiotic relationship symbiosis grow on rock,bark,burned forests,lava ﬂows<-- help break down to make microenvironment for other microorganisms to live exs:fruticose,crustose,foliose ‣ low lying,ﬂat,crusty looking ‣ various levels of pigment components: ‣ fungal member (hyphae network)(ascomycete or basidiomycete) (gets ﬁxed carbon) • provides physical environment gas exchange retention of h2o & minerals secretion of acids ‣ photosynthetic organism...green alga(provide ﬁxed C) or cyanobacteria (provide ﬁxed C & N) • occupy an inner layer below the fungal surface (gets nice area) - look at notes on paper (missed day) • Secondary Root Growth(occurs simultaneously w/ primary growth) vascular cambium(1st lateral meristem,gives rise to other elements)= one continuous cylinder formation ‣ between 1st xylem and 1st phloem of vascular bundle ‣ ground tissue btwn vascular bundles secondary growth xylem(dead cells w/ almost no cross walls) to the inside ‣ wood secondary growth phloem(living cells,have partially digested cross walls so photosynthate can move relatively fast through them) to the outside ‣ crushed at the end of the season(still there,but inactive...new layer forms on inside of old layer(towards middle part of phloem) ?- where can you ﬁnd the youngest parts of a tree? in primary growth- in tips of roots and shoots(length) (develops from apical meristems) in secondary growth,is whats adjacent to the vascular cambium (width) closest to the outside(secondary xylem) (vascular cambium grows and generates cells that differentiate into various types) • cork cambium= bark(consists of anything external to vascular cambium.so, secondary phloem,cortex,cork cambium,cork(so..phloem and periderm) (periderm helps make up bark) (forms from original cortex surrounding vascular tissue..differentiates into cambium cells,producing cork cells to the outside and another cortex layer to the inside)...dead at maturity.. suberin(waxy,protective) allow for protection of enlarging tree trunk. • heartwood...in middle...oldlest part of tree..wood darken..almost nonfunctional • sapwood..inside tree but outside heartwood..still somewhat functional • Secondary growth:periderm- cork cambium and cortex • cork cambium cortex derivite(parychyma cells differentiate to form meristematic cells) • cork cells to the outside sclerenchyma secondary cell walls with waxy suberin • phelloderm (parenchyma cells) to the inside • early spring wood has very large diameters...wide diameter conducting elements (trachea and vessels) • late summer wood...smaller diameters • bark- all tissus external to the vascular cambium secondary phloem periderm ‣ cork,cork cambium,phelloderm,secondary phloem (if any) • lenticels- gas exchange birch tree types ‣ slits in trees,apples,loosely packed cork cells ("nodes") on trees • girdling a tree can happen naturally or intentionally peeling bark off in a complete layer around an entire section of the tree (in a circle).....destroys the phloem and vascular cambium Chapter 29 • roots need oxygen (through roots and lenticels on tree) produces co2,which leaves roots • h20 and minerals travel up roots to regions of primary growth and goes up and out through leaf pores • water and organic mols moves in phloem • water and inorganic mols move in xylem (vascular tissue) • short distance transport- across cell membranes • bulk ﬂow- movement of things across membranes in response to pressures • plasmodesmata- small dissolved perforations in cell walls,allows cytoplasm and plasma membrane to be connected from cell to cell • plant transport routes apoplastic route- travels through apoplast (cell wall..doesnt cross membranes) symplastic route- travels through cytosol of cells (connected by plasmodesmata) must pass throgh some membranes transmembrane route- crosses cell membrane,into apoplast,then into symplast,repeat • compartments apoplast- cell walls and dead material symplast- continuum of cytoplasm • solute and water transport in plants long distance tranport ‣ bulk ﬂow ‣ requires pressure gradient • xylem under plus force • phloem under negative force short disance transport...across cell membranes ‣ active transport- needs atp...moves from [lower] to [higher]...allows cell to maintain uneven concentrations ‣ passive transport- doesnt need atp...solute/water moving down concentration membrane • simple diffusion- solute/water moves down [ ] gradient..dsnt need special protein carriers...slide through phospholipid bilayer • facilitated diffusion- special speciﬁc proteins that transport certain ions down [ ] gradient • osmosis • protons pumped to outside of cell so ph is lower creates energy gradients: ‣ membrane potential...other cells can bring solutes in up their [ ] gradient from proton pump(cotransporters and ion channels) ‣ proton gradient • osmosis- diffusion of water down its [ ] gradient,across a semi-permeable membrane...always passive water moves from a region of low solute concentration to a region of high solute concentration,...but still moving down its own [gradient] aquaporins- special protein facilitated diffusion molecules..allow plant and other cells to more closely control how much water moves by osmosis • water potential- psi ...measure of potential energy of water expressed in pressure units,MPa plant cell 0.5 MPa...has positive water potential bc of cell wall and pressure pushing out car tire 0.25 MPa home plumbing 0.5 MPa factors affecting water potential: ‣ pure water at normal pressure has 0 MPa ‣ solutes component- affect in a particular compartment ‣ pressure component ‣ pressure for each compartment • • solute addition decreases (-) • positive pressure increases (+) • negative pressure decreases (suction or tension) (-) ‣ high to low ‣ equilibrium ....water will stop moving when [ ]s are equal • must consider magnitude and sign of ‣ physical pressure increases animal cells outside the cell plant cells...turgor pressure ‣ rigid cell wall prevents expanision ‣ plant cell (inside) < environment (outside) • water moves into cell • internal hydrostatic pressure directed outward walled vs.unwalled cells ‣ ﬁgured 5.11 in book....or look in ch 29 slide • hypotonic in < out • isotonic in = out • hyertonic in > out • movement of xylem sap short distance transport ‣ osmosis,active & passive transport of cell membranes ‣ happens in root cells,cortex,endodermis (forces solutes and water to move through cell membranes if they havent already done so) long distance transport ‣ bulk ﬂow(pressure generates and tension is generated) ‣ happens in vessel elements and tracheids casperian strip...suberized layer of endodermal cell..along radial and transverse cell walls...what forces things through cell membranes and doesnt let them continue to go through apoplast • endodermis- selective sentry intermost layer of cells in the root cortex surrounds the vascular cylinder casperian strip,suberin ‣ blocks apoplastic pathway • ascent of water and minerals up xylem (from root tips up to top of tree and out leaves) root pressure...minor push force... ‣ mineral ions pumped into root xylem • soil > root water ﬂows in osmotically goes in thru cortex and into stele and vascular elements..increase in pressure causes upward push(pos pressure) of xylem sap cohesion-tension hypothesis:pulls water up by force... ‣ transpiration- evaporation of h2o from the stomates (must be open...to let water evaporate and to take in co2) ‣ water evaporates from leaf spaces...spongy mesophyll(air spaces...musty)...remaining water coats the surfaces of the cells...begin to pull on each other in a chain like manner tension develops at air-water interface • transmission of pull force cohesion(stick to themselves) & adhesion(stick to hydrophilic subs...tubules) of h2o ‣ helps water to move against gravity continuously water brought to leaf mesophyll thru veins(have xylem and phloem) adhesion to cellulose microﬁbrils cohesion of water to itself hydrogen bonding- give high tensile strength...allows long unbroken pillars of water water potential steadily decreases as you go up from the bottom • transpiration regulated by stomata plant controls water loss by stomates(mostly on bottom of leaf)- made of 2 guard cells located on bottom of leaf...adaptation to limit evaporation/ transpiration ‣ stomatal apparatus- stomata and 2 guard cells opening- guard cells swell(increase turgor pressure),causing a bowing out of the cells,leaving a hole in the middle of the two closing- guard cells shrink (decrease turgor pressure) guard cells...have primary cell wall... ‣ inner walls are very thick ‣ outer walls are thinner ‣ cellulose microﬁbrils wrap around guard cell radially • cause guard cells to bow outward when they swell...potassium ions ﬁll • opp when shrinking...potassium ions leave • blue light receptor- special protein in membrane that recieves blue light and starts signal trasduction pathway that starts pumping potassium ions into the cell,creating a membrane potential • transpiration affected by environment light co2... ‣ high levels:stomates tend to close bc getting enough co2 ‣ low levels:stomates tend to open bc not getting enough co22 circadian rhythm temperature... ‣ excessive heat:stomates close...high temp increases evaporation..limits water loss water status- trumps all other factors ‣ dehydrated:produces absizic acid...moves to leaves causing stomates to close...decreased photosynthetic rates • adaptations to limit water loss cacti(reduced leaves...spines) hairs(reﬂect sunlight) recessed stomates...sunk in pits...further limits evaporation • translocation in phloem (mostly in herbacious plants) transport of phloem sap- water with dissolved sucrose and other organic nutrients ‣ moves from sucrose source(producer) to sucrose sink (consumer) • can change depending on season and developmental stage of plant ex) leaves start out as sinks,then become sources when they are photosynthetic,then go back to sinks as they prepare to fall off for winter ‣ sucrose.. • can be active or passive transport from mesophyll cells to get it into sieve tube elements[devoid of certain elements...loaded w/sugar and sap) (can be helped by adjacent companion cells) • passive transport out of phloem • h+ gradient helps move sucrose require adjacent xylem elements ‣ provides water ‣ creates pressure head(pos pressure) bulk ﬂow ‣ high pressure --> low pressure pressure ﬂow hypothesis- phloem loads at source,then when it reaches the sink cells,it moves into cells by passive transport ‣ sucrose actively transported into sieve tube element,which decreases water potential ‣ water from adjacent xylem moves into sieve tube element,creating a positive pressure...then sap moves towards sink ‣ sucrose unloaded at sink,water potential at that part of sieve tube element decreases and the water recycles back into the adjacent xylem Chapter 28 - plant nutrition • most of plant comes from the air(co2),not the soil. • most of plant is water,but most of dry part of plant is organic mols • soils topsoil ‣ parts... • particulates derived from rock sand(largest),silt(middle),clay(smallest particles,hold water tightly) loamy soils are best..have = proportions of all 3 • humus...dead organic decaying material slow release of nutrients,nitrogen,phosphorus,etc..as well as air spaces • living organisms...esp bacteria(prep soil for plant roots),archaea,fungi, mycorrhizae,cyanobacteria(upper levels),protists,various invertebrates(esp.nematode worms...help airate soil) • air spaces soil particles are negatively charged,surrounded by water ‣ when root around: • root hairs surrounded by lower pH...releases H+ ions also H+ ions from proton pump(usesd to actively bring in other ions)...enables cotransport of ions h+ ions imp in cation exchange- pos ions(calcium,potassium, sodium) that adhere to neg soil particles... ‣ soil particle will exchange h+ with pos charged ion • mineral uptake by roons anions- neg charged ions...cant bind to soil particles ‣ imp:phosphate(po4,3-),nitrate(no3-),sulfate(so4,2-) ‣ organic mols better used in fertilizing soil cations- made available to roots by H+ exchange ‣ K,Ca,Mg • essential elements9table 29.1) macronutrients- c,h,o,n,p,k,Ca,Mg,s ‣ proteins,nucleic acids,chlorophyll ‣ needed for plants to complete life cycle micronutrients ‣ fe,cl,cu,mn,zn,mo,b • nitrogen ﬁxation- conversion of n2 to nh3 only done by bacteria ‣ ex) rhizobium,frankia,klebsiella nitrogenase....helps break n bonds ‣ inhibited by oxygen...why it happens in soil • plant root symbioses legumes(plant family)...plants w/ beneﬁcial bacteria in nodules ‣ ex)peas,beans,clover,alfalfa,soybeans,peanuts rhizobium(n ﬁxing bacteria) root nodules form that house bacteria (as a result of ) • bacteria enter thru root hairs...start beneﬁcial "infection" • enter special vesicle in cortex cells...called bacterioids • ~develop living,non-photosynthetic root cells ‣ why are root nodules pink? • leghemoglobin(produced by plants)..complexes o2 and helps keep oxygen low around roots so nitrogenase can fx ‣ mutualistic symbioses • bacteria supply nh4+ to plant • plant supplies CHO to bacteria mycorrhizae- white hyphal masses ‣ fungus gets ﬁxed C ‣ plant received increased SA for water absorption and enhanced mineral absorbtion ‣ endomycorrhizae (arbusular)...glomeromycetes...(85% of plants have endomycorrhizae) ‣ ectomycorrhizae • alternative plant nutrition: epiphytes...non harming ‣ plant growing on another plant to achieve hight to access sunlight • ex) staghorn fern,spanish "moss",vanilla orchid(climbs) parasitic...suck nutrition out of other plants ‣ ex) mistletoe,doffer,indian pipe Chapter 27 • Eukarya multicellular heterotrophic • unique to animals motile diploid gametic life cycle ‣ small motile sperm & large nonmobile egg ‣ asexual reproduction unusual no cell wall • in Unikonta group,Opisthokont • cholesterol...only in animals...in many steroid hormones • recall...choanoﬂagellates...unicellular group sister to all animals unicellular or live in colonies sponges...some called choanocytes...basal group of animals common ancestor:770 mya • Phylum Porifera...."pore bearer" divides by mitotic divisions to produce saclike stx w/ out deﬁned germ layers,muscle,or bone sessile lack symmetry lack tissues ﬁlter feeders several cell types ‣ choanocytes- collar cells- imp for feeding & sexual reproduction ‣ ameobocytes- communicates w/choanocyte to get food particle... produces spicules that give the sponge more support ‣ pore cells- porocytes- allow ﬂow of h20 thru body wall • Phylum Cnidaria named after special stinging cells in epidermis (cnidicites) carnivorous...active hunters ‣ tentacles w/ nematocytes ‣ gastrovascular cavity (one opening) that food is taken into • secretes enzymes that digest prey...unused pieces released out same opening forms: ‣ hydrozoans:(ex:hydra) sessile ‣ scyphozoans-jellies:~ planktonic form ‣ cubozoans-sea wasps ‣ anthozoan- sea anemone:ﬂower anemones,corals...stay in one place motile & sessile forms radial symm two tissue layers: ‣ endoderm- layer facing inside..gives rise to gastrovascular epithelium that secretes enzymes ‣ ectoderm- facing outside..tentacles...have primitive nerve net in their epidermis coupled w/ muscle cells (allows it to expand & contract) • cambrian explosion:535-525 mys (cambrian period:542-488 mya) precambrian forms:generally soft...ex:grazers,ﬁlter feeders,scavengers cambrian forms:large forms of other phyla evolved...hunters & the hunted ‣ bilateral symm (1st appears 670 mya) ‣ adaptations for capturing prey • ex) improved locomotion,grasping appendages ‣ defensive adaptations for avoidance • ex) mineralized skeletons,spines,shells hypoth for cambrian explosion ‣ predator-prey interactions ‣ atmospheric o2 • 3% --> 12% • supports higher metabolic rates ‣ Hox genes- genes regulating other genes • their products regulate other genes involved in patterns of development ex) how many segments,where legs & arms go • highly conserved among animals • animal body plans (~ helps classify animals) symmetry- ‣ radial(thru central axis) • oral(opening) & aboral sides (opp of opening) • sessile or planktonic(ﬂoats around) forms...environment meets organism same on all sides ‣ bilateral(down middle) • dorsal(back) & ventral (front) • right & left • anterior(top) & posterior(bottom) • cephalization- concentration of nerve/control cells (that recieve and process info from environment) at anterior end of organism • motile- move head ﬁrst ‣ none(ex:sponges) tissues- form from germ layers ‣ diploblastic • ectoderm- gives rise to epidermis,nerve net,& muscle cells • endoderm- gives rise to gastrodermis (produces enzymes & nutrient absorbtion) ‣ triploblastic • ectoderm- outside tissues • endoderm- lining of gut & organs • mesoderm- gives rise to muscles & skeleton coelom- body cavity(pockets) lined w/mesoderm w/ organs inside ‣ allows organs to move around inside ‣ can be present/absent..not much phylogenetic use • none(sponges) • evolutionary relationships among animals 36 phyla,most estbl'd by 500 mya all animals share a common ancestor sponges are basal animals eumetazoa is a clade of animals w/ true tissues (all animals except sponges...metazoa) most animal phyla belong to the clade Bilateria most animals are invertebrates (35 phyla) chordoata is the1 phylum that includes vertebrates • know ﬁgure 27.10...know current phylogeny ‣ imp:porifera,cnideria,chordata,anthropoda ‣ metazoa,eumetazoa,ctenophora,bilaterial,dueterostomia(includes chordates),lophotrochozoa,ecdysozoa • ecdysozoans- nemotodes & arthropods motling- shed exoskeletons through process called ecdysis • lophotrochozoans lophophore ‣ ﬁnger like feeding stx allowing organisms to ﬁlter feed • ex) ectoprocts & brachiopods trochophore ‣ distinctive trochophore larva stage • ex) annelids • ctenophora- absence of some stxs,but have genes for nerves look like jellyﬁsh,but no stinging cells,have sticky projections to catch prey • notes on paper • arthropod evolution segment fusion [exoskeleton(pariphis)...movement,support,desiccation prevention] jointed paired appendages appendage modiﬁcation/specialization ‣ walk,feed,swim,copulate • invasion of land by animals multiple events arthropods (450 mya) ‣ insects (410 mya) • wings- outgrowths of cuticle/exoskeleton • tracheae (gas exchange)- tube system leading to holes on outside of body wall...reach every cell in the body • coevolution w/plants vertebrates (365 mya) ‣ tetrapods ‣ ex) tiktaalik...has tetrapod & ﬁsh characteristics...transitional animal • neck,head,eyes close together,arms from shoulder,ribs,ability to life body off ground,ability to respire • tetrapod body plan evolution ‣ ﬁns -->limbs • forelimb bones,wrist,digits • full rib cage lung support • neck & shoulders head movement • skull eye placement basal tetrapods ‣ amphibians • gave rise to salamanders,caecilians,& frogs & toads • can live away from h20,but need it for reproduction[external fert • have lungs,but most respiration takes place across skin amniotes ‣ amniotic egg- • allows reproduction to take place in shell(hard or leathery) w/out h20 • albumin- egg white...nutrition • air space • yolk- nutrients • chorion- membrane used in gas exchange • allantois- contains waste • amnion- membrane closest to embryo...contains ﬂuid reptiles/some mammals ‣ internal fert & required stx ‣ derived characters of amniotes • impermeable skin keratin- protein in skin cells scales,hair,feathers • ribcage/ventilation- holds lungs • limbs to elevate body- enhances movement • amniotic egg extra-embryonic membranes w/ or without shell • crocodiles more closely related to birds than other reptiles • don't exactly know where turtles developed from..but closer to birds and crocodiles • tuataras- lizard like...sister to squamates • squamates- snakes & lizards • features of non-ﬂying(non-avian) reptiles scaly skin lungs internal fert 3 or 4 chambered heart- increases efﬁciency ectothermic- get body heat from environment • transitional form....bired/reptile...archaeopteryx...~150 mya • derived characters of birds(clade of reptiles) wings/feathers no urinary bladder(dont store waste) single ovary 4 chambered heart endothermic- maintain constant body temp generated from high metabolic rate light skeleton no teeth • mammals..began evolving ~200 mya...1st true mammals ~150 mya only increased in size after dinosaur extinction body hair & mammary glands basal group:monotremes (ex:platypus)...lay eggs..milk comes out of skin marsupials (ex:kangaroo) ‣ early developmental birth ‣ embryo crawls up to pouch,attaches to nipple,then continues development while attached eutherians (ex:monkeys,apes,humans) ‣ longer gestational period derived mammal features ‣ mammary glands ‣ hair,dermal fat- barrier layer to retain heat,assists endothermy ‣ larger brain ‣ 4 chambered heart ‣ endothermic ‣ teeth adapted to diet ‣ remodeled jaw humans closest living relative is chimpanzee & bonobos Chapter 32 • 4 tissue types epithelial ‣ stratiﬁed squamous- layers of ﬂat cells..line places that need constant replacement (mouth,skin,anus) ‣ pseudostratiﬁed columnar epithelium- surface has cilia,lines trachea & oviduct,looks like multiple layers bc nuclei are in diff places,but really only one layer • apical surface- lines interior of trachea...ciliated..move mucus ‣ simple squamous epithelium- single layer of epithelial cells close to capillaries ‣ simple columnar epithelium- absorption of nutrients...small intestine ‣ cuboidal epithelium- kidney,composes glands(produce hormones) connective- all...cells in extracellular matrix(can be solid,rubbery,or liquid) (can be very minimal) ‣ loose connective tissue- ﬁbroblasts...produce ﬁbers(collagen & elastic ﬁbers)...gives padding around joints & organs ‣ ﬁbrous connective tissue- ﬁbroblasts...parallely oriented ﬁbers tendons(bone to bone)/ligaments(muscle to bone) ‣ bone- osteocytes...hard dense solid ecm...collagen & elastin(not brittle)..very well vascularized ‣ adipose tissue- adipocytes...not much ecm..fat tissue(triglyceride droplets...enlarge or shrink due to weight changes)...imp for energy storage,protective padding,padding for unprotected organs ‣ cartilage- chondrocytes...rubbery ecm..found in joints(pads bone ends)..not vascularized(takes awhile to be repaired) ‣ blood- rbc,wbc,plasma(ecm..water based w/ many things dissolved in it) muscle ‣ skeletal- parallel muscle ﬁbers..can contract/relax...voluntary control ‣ smooth- in internal organs- same proteins as in skeletal muscle..contract & relax...spindle shaped(close together),each has single nucleus..under nervous & hormonal control ‣ cardiac- similar to skeletal due to parallel arrangment,but also branched & connected(physically & electrically...must contract & pump as a unit) • intercalated disk- individual cells closely attached (p&e) nervous ‣ neurons- transmission of signals • dendrites- receive signals then moves down axon to some other cell ‣ glia- interspersed among neurons...assist in architecture(brain & spinal chord) & getting nutrients each organ system usually includes all 4 types • how stability is maintained • conformers- temp does what outside temp does • regulators- regulate temp internally...dsnt change w/ environment • homeostasis- maintenance of internal balance set point negative feedback- detecting change in set point,then processes occur that cause a decrease in that stimulus that make it return to the set point regulates: ‣ cellular pH (speciﬁc) ‣ intracellular [calcium] ‣ plasma glucose levels ‣ osmotic balance homeostasis--> change in variable detected by sensor/receptor--> control center sends order to response/effector which restores homeostasis • thermoregulation ectothermy ‣ internal eat source ‣ regulated to set point ‣ metabolically expensive ‣ mammals & birds ectothermy ‣ external heat source and behavior ‣ body temp can be adjusted ‣ invertebrates,ﬁsh,amphibians,non-avion reptiles • radiation & conduction(direct contact) allows heat absorption • evaporation & convection(moving substance transfers heat (ex:wind,water)) allow heat release • counter-current exchange system- blood going one direction transfers heat to blood going the other direction • human thermostat(sensor/control center) in hypothalamus • homeostasis positive feedback ‣ uncommon ‣ stimulus ampliﬁcation ‣ culminates(gets more intense as it progresses) in the end of a process • ex) birth,suckling • Signal Coordination only certain signals are picked up by certain receptors (speciﬁc) ‣ nerves detect speciﬁc things then integrate to the brain to form the correct response long distance pathway- ex)spinal chord to toe cell to cell pathway- ex) release chemicals(hormones) to neighboring cells major pathways: ‣ stimulus causing endocrine cell to release hormones • signal travels to about every cell in the body,but only the cells with the appropriate receptors receive the stimulus and respond • target tissue:receptor speciﬁc • timeframe adaptive for gradual changes ‣ signaling by neurons- nerve cell to speciﬁc location(where the dendrites terminate)..faster pathway • target tissues:neurons,muscle cells,endocrine cells,exocrine cells • timeframe is adaptive for immediate changes • protein hormones cant cross cell membrane...initiates signal transduction pathway when they touch the receptor outside the cell • non protein hormones diffuse across membrane to intracellular receptor • evolution of hormone function prolactin(from common ancestor)...support for phylogenic relationships ‣ mammals:mammary gland dev,milk synth ‣ birds:reproduction,fat metabolism ‣ amphibians:delay of metamorphosis ‣ ﬁsh(FW):salt & water balance • Osmoregulation & excretion osmoregulation- salt & water balance nitrogen excretion- protein & nucleic acid breakdown ‣ ammonia(nh3) • hypoosmotic- less solutes dissolved in it • hyperosmotic- more solutes dissolved in it • environments of animals FW aquatic ‣ hypoosmotic(to tissues of organism) marine aquatic ‣ isoosmotic(") ‣ hyperosmotic(") terrestrial ‣ desiccating(") • osmolarity expression of total solute concentration expressed as osmotic pressure:milliosmoles/L (mOsm/L) sum of concentrations of all dissolved subs pure water= 0 mOsm/L sea water= 1000 mOsm/L freshwater ~ 15 mOsm/L (very low) humans & other terrestrial vertebrates ‣ blood plasma ~ 300 mOsm/L • NA+ 145 mM • K+ 5 mM • Cl- 110 mM
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