- Created by: olivia hodges
- Created on: 05-04-13 16:34
origins of life
life - units that reproduce by division, properties of which are inherited by offspring, random mutations retain variation, some offspring more fit than other and will adapt to enviro. Replication begun with RNA to DNA, membranes evolved. All cells have membrane to regulate traffic, have enzymes and proteins for structual support, have DNA, transcription and translation. Have continual interaction between membrane, DNA and proteins within cell. Smalles single cells - bactera prokaryotes (2um). Eukaryote cells are larger 3-1000um. Energy comes from splitting energy rich phosphate bonds. almost all enzymes involved with energy metabolism are found in all bacteria cells.
By 3.5 bya first sign metabollic diversification, ocmplex microbial communitied cycled carbon etc though biosphere, photosynthesis occured, no one ate each other, bacteria competed for a common resource. o2 was first produced as waste, then consumed through oxidation of reducing compound e.g ferrous iron, seas were anaerobic, 2byaa o2 was 1-2% current, by 600mya o2 was 10% current. meant eukaryotes could eat, anaerobic eu cells took up aerobically respir bacteria in endosymbiosis - mitochondira evolved. Aerobic bacteria need 1% o2, aerobic EUs need 1-2% animals need 10% current levels. aerobic resp meant more energy, so supports larger food chain, atmospheric ozone layer formed protecting organisms from UV light. Invasion of land slow, pros first. tree of life shows all life related, most evolution is bacterial, but doesnt reflect phenotypic complexity
background extinction and mass extinction. mass extinction - one group replaces another, small animals survive big dont, weed species more likely to survive, some groups have competitors removed, acceleration of the replacement of one group by another, some taxa completely unaffected. earths atomsphere - nitrogen and o2 increased, H and Co2 decreased. ancient fossils show microbes 3.4bya, early inverts 1bya, giant amoeba 1.8bya. animals from the edicaran fauna - rangea and spriggina. earliest cambrian faunas - trilobite and molluscan. burgess shale - animals that can be assigned to known taxa - pirania (sponge), habelia and leancholia (arthropods), canadia (polychaete). movement of tectonic plates moved triassic to cretaceous period.
patterns of extinction in different taxa over years - trilobites, brachiopods and nautiloids decreased hugely. gastropods increased steadily and largely. so did bryozoans and sponges and anthozoans.
Eukaryotes - similar to arche: gene sequences and protein synthesis. Similar to bacteria in energy metabolism and cell membrane. protists - unicellular eukaryotes. use Phagotrophic, phototrophic and mixotrophic ways to get nutrition. have cytoskeleton unlike pro cells. for mechaincal support and movement and means more varied cell shapes, can also take up other cells (phagotrophy). some have scales. cosmopolitan distribution - ubiquitous, continually being dispersed. locomotion - flagella, cillia 9+2 microtubules, pseudopodia and mucus. have different pigmentation due to diff types of chlorophyll and other pigments.
ciliates - monophyletic, have cilia, generally predatory some parasitic or contain symbiotic algae. e.g blephanisma japonium, vorticella, paranecium. all possess 1 macro and 1 micronuclues, contractiles vacuole, cytosome, digestive vacuole.
apicomplexa - e.g plasmodium (malaria) have an apicomplex and form spores. haploid nuclues, flagella only found in motile gamete, basal bodies, parasitic, unicellular, RER, mitochondira, conoid, polar ring.
hetertrophic flagellates - polyphyletic, huge diversity, have one to many flagella. e.g choanoflagellates - collar of microvilli traps baceria, root of tree that lead to sponges, flagella to get food, resist infection - cysts, feed,motile repro - trophozoites.
giardia - flagelate, no mitochondira, alimentary parasite, in with food out with faeces, big problem in coping with enviro fluctuations - forms cysts to cope. alimentary parasites ahve life cycle where cysts and trophozoites alternate. cysts - resistant to desication by pH and enzymes, infective, passed on in faeces. trophozoites - redproduce, feed, motile.
amoeba - also incluce gut parasites e.g E.dispar (non pathogenic only causes diarohea) and E.histolytica (more invasive causes amebiasis which kills). all have pseudopodia and move by cytoplasmic streaming. types monopodial - one foot - slug like. some have many moving in many direction at once. some have shell or test helps them live in soil - move into the test when there is no water.parasitic amoebae - turbulinea, single large pseudopod, contracile vaculoe to maintain osmotic equilibrium, phagocytosis. slime moulds - look more like fungi. helizoans - cartwheel like serious predators. foraminifera - ancient groups shells found in fossil record.
labyrinthula - slime nets - flagellated and amoeba-like. Kinetoplastids - one mitochondiran with one or more masses of mitochondrial DNA - the kinetoplast. 2 groups - the bodonids : use flagella to move some free living most parasitic. trypanosomes: both have flagellate and non-flagellate stages of life cycle, some very parasitic, mostly of blood. big problem for blood parasites moving from one host to another - use vectors e.g insects.
4 ways of escaping host immune response - trypanosomes employ antigenic mimicry - process controlled by 40% of genome. antigenic variation - Parasite changes its surface layer every few days and never repeats same coating. immuno suppression, or living in an intracellular habitat.
class turbulina. Arcella vulgaris (amoebozoa) - shelled freshawater ameoba. has phylone where pseudopodia extend through. has shell and cytoplasmic extenstion and contractile V
class hydrozoa. hydra, cnidarian. radial symmetry, mouth, coelenteron, tentacles, pedal disc, sexual bud breaks off to form new hydra, battery.
Euglena (protozoa) Phylum: Euglenozoa. flagellum, stigma -light sensitive, pellicle, polysaccharides stored by photosynthesis, pyneioud, chlorplasts, vacuoles, reservoir.
vorticella (ciliate) - cillia, striated fibril called a kinetosesmos extends from each basal body in direction of adjasent cilium of same row, undulating membrane, mouth = cytostome, stalk, macro and micro nucleus.
giant puff ball has been used to smoke bees out of hives and as anaesthetic. coprinus atramentarious - common ink cap once used to make ink. dried fruiting bodies of amanita muscaria were used as natural insecticide. early medical use - rub mould from bread of wounds.Jelly ear was boiled in milk to help sore throat. doctrine of signatures - mediaval belief that god prodived clues for medical useage in shapes and colours. e.g ling shaped lobaria pulmonaria. chaga russian cure for cancer derived from polyphore inonotus obliquus that looks like cancerous tissue, contain anti-cancer compound befungin.
modern use - toothpaste gluconic acid from aspergillus niger. toast requires saccharomyces cerevisiae. cultivated mushrooms agaricus bisporus. Quorn from fusarium graminearum. alcohol has been fermentated with aid of fungi. rennin - to make cheese can be taken from plant pathogen C.parasticia.
penicillin - P.notatum by fleming. cortisone - steroids, R.arrhizus able to convert disogenin to cortisone e.g of biotransformation (biological process whereby organic compound is modified into a recoverable product by action of enzymes within cells)
Glycerols produced by S.cerevisiae, wide use as solvents and sweetners. invertase - soft centres in chocolate. lactase - hydrolysis of lactose in milk products. pectin - fresh juices
vitamins and pigments produced by fungi. beta-carotene - colouring agent for margerine. B vitamins from yeast as nutritional supplement.
plant growth factors - giberellic acid from F.moniliforme. can regulate fruit setting and increase yeild. biological control agents - chemical pesticides. mycoparasites are fungi which parasitize other fungi. P.lilacinus is registered as biocon and is soil borne fungus which parasitizes the eggs of some nematodes. Green muscle is a spore powder of oil miscible concentrate. ****-rot in trees for timber is serious pathogen ,can be controlled by p.gigantea by hyphal interference. mycorrhizal inoculants - sprinkled onto roots during transplanting.
bioremediation - contamination of soil, ground and water by hazardous chemicals and wastes. Need to remediate contaminated sites. bioremediation uses living organisms to metabolise and detoxify enviro pollutants. e.g washwater treatment. most research in lignin-degrading enzyme of white rot fungi. mycofiltration is imprgnation of fungal spores into fabric landcaping cloth which are overlaid onto contminated ground and fungi act as a filter, trapping and degrading contaminants.
study of fungi - mycology. eukarotic which means nuclear membrane and complex cells. include mushroom, rust, smuts, puffballs, truffles, moulds and yeast. tree fungi originated same time as animals and green plants. mushrroms yeast and moulds may have evolved after angiosperm plants in last 200 my. what distinguishs them from other eukarya - unique mehtod of lysine synthesis (Aminoadipic acid pathway). rigid cell wall is composed of B-1,3 and B-1,6 linked glucans and chitin. cell membranes contain ergosterol (animals - cholesterol, plants sitosterol).Also: store food as glycogen (as do animals). generally haploid, produce secondary metabolites.
grown as hyphae or yeasts they exhibit apical growth, hyphae build to form a mycelium, produce spores by means of sexual and asexual repro. fungi are heterotrophic (use organic compounds as carbone source). Have absorptive nutrition e.g utlize cellulose by release of extracellular enzymes. major decomposers of polymers such as cellulose and lignin. maintin enviro carbon levels by carbon cycle. can be saprophytes: obtain nutrition from dead organic material. Biotrophs: obtain nutrition from living host tissue e.g lichens and endophytes. Necrotrophs: kill host cell and feed on dead tissue.
mycorrhizal associations - fungi can form interactions with roots of terresterial plants increasing nutrients available to plant and fungi return supple of carbon.
fungi diversity 2
can cause human infection e.g ringworm and thrush. fungi classed according to cell strucutre and repro stages so led to 5 phyl : mastigomycotina, zygomycotine, ascomycotine, deuteromyctina and basidiomycotina. however advent of new biochemical and genetic techniques has meant that mastihomycotina used to have 2 classes chytridiomycetes and oomycetes but oo are not longer considered true fungi. because lysine is made via diaminopimelic acid, cellulose major cell wall component, closer to plants.
chytridiomycota - saprophytes and facultative parastites, found in moist soil and fresh water habitats where they decompose cellulose. baited from water using hemp seed as substrate. produce motile zoospores as means of asexula repro. specialed groups of chytrids grow in the rumen of herbivors where they degrade cellulose.
zygomycota - soil dwelling saprophytes. several members found on animal poo. important in the rot of sweet potatoes, strawberries and tomatoes, common as bread mould and oftern termed 'pin-head' funig. one causes mucormycosis a human infection common in diabetes, leukemia and cancer.
fungi diversity 3
ascomycota - largest phylum. e.g penicillin and bakers yeast. terrestrial, aquatic or marine. grow as saprophytes, biotrophs, necrotrophs and parasites. prodice plant growth regulatores. fungal secondary products may act as pheromones e.g truffles.
basidiomycota - second largest. familiar fleshy fungi. mushrooms, toadstools, puffballs etc. most saprophytes causing decay of leaf litter, wood and dung. some toadstool associated with rtees in form of mycorrhiza. rusts and smuts are also in this which are plant pathogens. e.g of basidiomycota - dead mans fingers, dryads saddle, jews ear, sulphur tuft, silver leaf bracket