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UWO Biology 1002B February Exam Notes.docx

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Biology 1002B
Tom Haffie

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1002B LECTURES 19 EXAM NOTESLECTURE 1 LIGHT ENERGY AND INFORMATIONTextbook No theoretical reason or empirical evidence that evolutionary lineages increase in complexity over timeEukaryotic cells more complex than prokaryotic cells animalsplants more complex than protistsMeasure complexity o Genome sizegenes in an organism o Gene copy numbercopies of a gene in a gene family from gene duplication o Increase in sizeover evolutiono Number of geneso Number of parts o Number of cell typeso Increased compartmentalization o Number of interactionsgene gene networks celltocell o Number of interactions between partsincreasing functional complexity over evolutionIncrease in number of types of cells o Increase in complexity in embryonic development in the transformation from a zygote to a multicellular organism o Most common methodIncrease in organismal size o Embryonic development increasing complexity accompanied by increasing size o Not a criteria because no sustained size increase over lineages o Evolution causes a decrease in sizeEx Parasites organisms inbetween sand grains at high tides on beaches large animals after isolation on islandsLife style o Parasitism became successful in invertebrates as large potential hosts evolved o Parasites evolved as organism simplifieddisappeared o Life cycle of a parasite may become complex and have many intermediate hosts o Adaptive advantage of a life cycle complexityParasite increases population in intermediate hostsincreases chances of infecting primary host Spreading in early stages of intermediate hosts conserves resources of primary hostparasites productive for longer periods Physical Nature of LightLighto Source of energy that directly or indirectly sustains organisms o Information about the physical world that surrounds organismso Captured by organismGreen alga Chlamydomonas reinhardtiio Single celled photosynthetic eukaryote in ponds and lakes o Uses light as energy and information o Single large chloroplast that makes energyrich molecules from light o Eyespot that is a light sensor that lets individual cells to get information about the location and intensity of a light source What is LightSun converts 4 million tons of matter into energy each secondenergy given off as electromagnetic radiation that travels at the speed of lightElectromagnetic radiation has distinct wavelengths126o Cosmic rays 10 to Radiowaves 10m Lighto Part of the electromagnetic spectrum that humans can see with their eyes 400700nm o No mass o Particle wave dualitybehaves as a wave and particleo Made of a stream of energy particlesphotons o Wavelength and energy of photons have an inverse relationship Light Interacts with MatterLight can interact with matter and cause changePhoton that hits an object can be o Reflected o Transmitted o AbsorbedSource of energyWhen energy of photon is transferred to the electron in a molecule causing the electron to be excited moving it from the ground state to an excited stateOnly when photon energy equals energy difference of ground state and excited state otherwise transmittedreflected Pigments Efficient at absorbing photons Chlorophyll aphotosynthesis retinalvision indigodye jeansConjugated system o Region where C atoms are covalently bonded with alternating singledouble bondso Results in delocalization of electronso Electrons arent close to a certain atom or bonded so they can interact with photons of light Pigments absorb light at very different wavelengths because of different number of excited states for the excitable electronsPhoton absorptioncolourPigments colour is because of the photons of light that it doesnt absorbphotos are reflectedtransmitted LectureLightsource of energy and information about the environmentGreen alga Chlamydomonas reinhardtiio Model system for understanding basic biologyCilia and flagella structure and function Photosynthesis o Distantly related to plants and animals o Unicellular with 2 flagella o Sexually active light harvesting carbon reducing hydrogen belching planimalo Used as source of energy and information o Large central nucleus with genes o Basal body 2Leads to the development of flagella and cilia Found at the base of any cilium or flagellumo Endoplasmic reticulum golgi ribosomes site of protein synthesis o More than one mitochondrion center of cellular respiration o One chloroplast o Mitochondriachloroplastmajor energy transducing factories of the cell o PyrenoidSite of carbon fixation conversion of CO to natural sugars 2o Eyespot Found within the outer membrane of the chloroplast but has no direct relation to photosynthesis it maximizes light harvesting for photosynthesisGenerates and electrical signal and controls flagella through a signaling pathwayHas a pigment called carotenoid carrots beta keratin o Extremophiles Evolution of complexity o Number of different components entwined to make a structurefunctionIncreased complexity with more components o Can be measured by the increase in size Eukaryotes are bigger than prokaryoteso Measure of genome size is not a consistent measurement method of complexityo Measure of protein coding genes PCG Rather than all your genes because the majority of genes dont code for anything o Evolution of multicellularity the more complex organisms usually have many different types of cells reproduction vs somaticBeing part of a multicellular organism guarantees deathChlamydomonas is unicellularVolvox is multicellularPhototaxis o Eyespot is needed for phototaxis o Wild type is running away from photons Not the right wavelengthenergyfrequency wrong colour or intensity then they would just not detect the light at all Too much exposure to energy may denature the proteins and cause mutations Too much energy causing too much replication because photosynthesis is depleting resources or accumulating oxygen waste ROSreactive oxygen species with too many radicals that cant be gotten rid ofHigh light can destroy the photosynthetic apparatus o Eye can produce an image by detecting light and causing flagella to move complex o Eyes more complex than eyespot but both have the same ancestorhomologous o Two types of photoreceptor cells found in the back of the eyeretina Rods 120000000Photoreceptor cells made of stacks of discs that have individual photoreceptorso Photo receptorblue dot found on discs in rodCones6000000o Photo transductionhow light is used by the eyePhotoreceptor on membrane binds to pigment Gets hit by photon and the shape of the photoreceptor changes from cis retinal to trans retinalphoto transduction pathwayActivates the protein transducin that activates the enzyme phosphodiesterase Phosphodiesterase cleaves 3 bond of cyclic GMP and bonds phosphate to 5 cGMP5GMP
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