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Biology 1002B Lecture 1.docx

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Biology 1002B
Tom Haffie

LECTURE 1: LIGHT: ENERGY AND INFORMATION Textbook :  No theoretical reason or empirical evidence that evolutionary lineages increase in complexity over time  Eukaryotic cells more complex than prokaryotic cells, animals/plants more complex than protists  Measure complexity: o Genome size – genes in an organism o Gene (copy) number – copies of a gene in a gene family from gene duplication o Increase in size – over evolution o Number of genes o Number of parts o Number of cell types o Increased compartmentalization o Number of interactions – gene, gene networks, cell-to-cell o Number of interactions between parts – increasing functional complexity over evolution  Increase 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 method  Increase 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 size  Ex. Parasites, organisms in-between sand grains at high tides on beaches, large animals after isolation on islands  Life style o Parasitism became successful in invertebrates as large potential hosts evolved o Parasites evolved as organism simplified/disappeared o Life cycle of a parasite may become complex and have many intermediate hosts o Adaptive advantage of a life cycle complexity  Parasite increases population in intermediate hosts  increases chances of infecting primary host  Spreading in early stages of intermediate hosts conserves resources of primary host  parasite’s productive for longer periods Physical Nature of Light  Light o Source of energy that directly or indirectly sustains organisms o Information about the physical world that surrounds organisms o Captured by organism  Green alga Chlamydomonas reinhardtii o Single celled photosynthetic eukaryote in ponds and lakes o Uses light as energy and information o Single large chloroplast that makes energy-rich 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 Light?  Sun converts 4 million tons of matter into energy each second  energy given off as electromagnetic radiation that travels at the speed of light  Electromagnetic radiation has distinct wavelengths o Cosmic rays (1012) to Radiowaves (10 m)  Light o Part of the electromagnetic spectrum that humans can see with their eyes (400- 700nm) o No mass o Particle wave duality – behaves as a wave and particle o Made of a stream of energy particles – photons o Wavelength and energy of photons have an inverse relationship Light Interacts with Matter  Light can interact with matter and cause change  Photon that hits an object can be o Reflected o Transmitted o Absorbed  Source of energy  When 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 state  Only when photon energy equals energy difference of ground state and excited state, otherwise transmitted/reflected  Pigments  Efficient at absorbing photons  Chlorophyll a  photosynthesis, retinal  vision, indigo  dye jeans  Conjugated system o Region where C atoms are covalently bonded with alternating single/double bonds o Results in delocalization of electrons o Electrons aren’t 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 electrons  Photon absorption = colour  Pigment’s colour is because of the photons of light that it doesn’t absorb  photos are reflected/transmitted Lecture:  Light = source of energy and information (about the environment)  Green alga Chlamydomonas reinhardtii o Model system for understanding basic biology  Cilia and flagella structure and function  o Distantly related to plants and animals o Unicellular with 2 flagella o Sexually active, light harvesting, carbon reducing, hydrogen belching planimal o Used as source of energy and information o Large central nucleus with genes o Basal body (2)  Leads to the development of flagella and cilia  Found at the base of any cilium or flagellum o Endoplasmic reticulum, golgi, ribosomes (site of protein synthesis) o More than one mitochondrion (center of cellular respiration) o One chloroplast o Mitochondria + chloroplast = major energy transducing factories of the cell o Pyrenoid  Site of carbon fixation (conversion of2CO to natural sugars) o Eyespot  Found within the outer membrane of the chloroplast but has no direct relation to photosynthesis; it maximizes light harvesting for photosynthesis  Generates and electrical signal and controls flagella through a signaling pathway  Harvests light and generates an electrical signal and controls flagella  Has a pigment called carotenoid (carrots, beta keratin) o Extremophiles  Evolution of complexity o Number of different components entwined to make a structure/function  Increased complexity with more components o Can be measured by the increase in size  Eukaryotes are bigger than prokaryotes o Measure of genome size is not a consistent measurement method of complexity o Measure of protein coding genes (PCG)  Rather t
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