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Biology 110 Exam Notes

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Matthew Smith

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BIOLOGY EXAM NOTES 10/9/2012 7:37:00 PM Life and Light A Green Algae  Using light for both energy and information  Eyespot: light sensor The Sun  Optimal distance from the sun o Enables us to use suns energy  Produces electromagnetic radiation Photosynthesis  Retinal absorbs light  Changes concentrations  Protons get pushed out cell  ATP is created from retinal  Potential energy o Energy stored as ATP can be used Electromagnetic Spectrum  The shorter the wave lengths - higher energy  The longer the wave lengths - lower energy What is Light?  Electromagnetic radiation that humans can detect with their eyes  Travels in waves - made of photons  Absorbed by pigments Light Interacting With Matter  Wavelengths can be reflected, transmitted or absorbed  Absorption of light occurs when the energy of the photon is transferred to an electron o Excites the electron, moving it from its ground state to a higher energy level (excited state) o If the photon’s energy equals the energy difference between the electron’s ground state and excited state Pigment Structure  Conjugated system o Alternating double/single carbon bonds o Delocalization of electrons  Not tightly held between one atom to the next  More available of absorbing photons of light Absorption of Light by Chlorophyll  Colour is the result of wavelengths of light that are not absorbed by a pigment  Able to absorb red light o Must exactly match the difference of energy between the ground state and the next highest energy state  Red has a longer wavelength: uses less energy  Synthesize NADPH and ATP  Carbon dioxide - carbohydrates Halobacteria  Contain a pigment proton complex - bacteriorhodopsin  Captures photons of light that provide the energy supply needed to pump protons out of the cell  Resulting in difference in H+ concentration  When absorbs, pigment molecule changes shape o Protein change shape - able to transport protons from inside the cell to out Light As A Source of Information: Photoreceptors  Photoreceptor o Serves as a light sensing unit of the eyespot  Rhodopsin o Most common photoreceptor o A highly conserved photoreceptor  Consists of a pigment molecule (retinal) bound to a protein (opsin)  Absorption causes retinal pigment molecule to change shape  Triggers alternations in opsin protein - downstream events  Intracellular ion concentrations  Electrical signals An Eyespot: Sensing Light Without Eyes  Found within the chloroplast  Focuses and directs incoming light toward the photoreceptors  Does not play a role in photosynthesis  Phototaxis o Cells respond to light by swimming o Allows the cell to stay in the optimum light environment to maximize light capture for photosynthesis Photomorphogensis  Phytochrome in photoreceptor in plants  Process by which plants develop in the light  Exposed to red light - becomes active and initiates a signal transduction pathway that reaches the nucleus The Eye  What distinguishes the eye of a simple invertebrate form the eyespot of the green algae? o Vision  Requires a brain to interpret signals send from eye  Co evolution Ocellus of Planaria  Ocellus o Contains thousands of individual photoreceptor molecules o Reaction carries them directly away from the source of light toward darker areas o The risk of predation is smaller  Planaria o Organ is used to sense light intensity and direction to a light source o Compound eyes and single lenses Compound Eye of a Deer Fly  Brian receives a mosaic image of world Octopus Eye  Eyes with single lenses - camera eyes o Evolved by variation and natural selection form a primitive eye Darwin and the Evolution of the Eye  Evolved over time  Similarities in their underlying developmental program  Similar set of highly conserved genes to orchestrate eye development  Gene Pax6: master control gene - eye formation Using Light to Tell Time: Circadian Rhythms  Sleep/wake cycle  Body temperature changes form light  Circadian rhythms not direct response to light  Light is required to SET cycle  Every organism has one The Role of Light in Behaviour and Ecology  Attract members of the same species  Role in communication  Bright colours means health  Beta carotene o Breaking down potentially harmful reactive oxygen species o Melanin based pigments found in darker colourations of birds  Attract pollinators  Camouflage Life in the Dark  Decreasing light levels o First lose our ability to see colour, followed by shapes o Photoreceptors of the eye remain functional Bioluminescence  Able to make own light The Cell 10/9/2012 7:37:00 PM Cell Theory  All organisms composed of one or more cells  Cell is the basic structural and functional unit of all living organisms  Arise from division of pre existing cells (cell division)  Cell is the smallest organism of life  1600’s o Robert Hooke (cellulae) and Anton van Leeuwenhoek (animalcules) - first observed cell  1800’s o Robert Brown: nucleus o Mathias Schleiden: plants = cells, nucleus = development o Theodor Schwann: animals = cells o Rudolf Virchow: cells - pre existing cells Basic Features of Cell Structure and Function  Contain highly organized systems of molecules - DNA + RNA  Cells use chemical molecules or light as energy sources  Respond to changes in their external environment by alternating their internal reactions  Cells duplicate and pass on hereditary information - cellular reproduction Cell Diversity: Microscopy  Technique for producing visible images of objects that are too small to be seen by the human eye  Light microscopy - light to illuminate specimen  Electron microscopy - electrons to illuminate specimen  Magnification - ratio of the object as viewed to its real size  Resolution - minimum distance by which 2 points in the specimen can be separated an still be seen as 2 points o The shorter the wavelength - better resolution Why Aren’t Cells Bigger?  Surface area to volume ratio  Volume - capacity for chemical activity o Produce bi product that are potentially harmful o Remove waste + bring in nutrients  Surface area - amount of transport in and out of cell o Increase surface area - flattening, surface folds  Volume increases faster then the surface area Prokaryotes  No nucleus  Make up bacteria + archaea  Nucleotide o DNA containing central region  No boundary membrane separating it from cytoplasm Eukaryotes  Nucleus  Plants, animals, fungi, algae, protozoa  Contains membrane systems - form organelles with their own environment + functions  Nucleus o Cytoplasm surrounds it o Enzymes for replicating and repairing DNA o Proteins are imported depending on amino acid sequence o Contains one or more nucleoli  rRNA + proteins - ribosomal subunits  Ribosomal subunits leave nucleoli + exit nucleus - join mRNA - ribosomes  Organelles o Biochemical pathways to be concentrated o Enzymes increase efficiency o Segregated - no biochemical pathways competing, product of one pathway can inhibit another Similarities Differences: Eukaryote Cells Plasma membrane -Separation of DNA and cytosol by -transporting materials into and out nuclear envelope of the cell -Presence of membrane bound -separating the cell from the externalcompartments (mitochondria, environment chloroplasts, ER, Golgi complex) Cytoplasm -Highly specialized motor proteins -synthesis and assembly of molecules - growth + reproduction Cytoskeleton -maintain proper shape of the cell -cell division + chromosome segregation DNA organized into Chromosomes Electron transport chain -Generating ATP -Eukaryotes: mitochondria -Prokaryotes: plasma membrane Ribosomes  Responsible for translating proteins  Eukaryotes o Free in cytosol o Attached to ER  Found in mitochondria and chloroplasts Endoplasmic Reticulum  Extensive interconnected network of membranous channels and vesicles  Rough ER o Ribosome studded o Make proteins  Become part of cell membrane  Secreted from cell o Chemical modifications  Addition of carbohydrates to produce glycoproteins  ER lumen  Smooth ER o Synthesize lipids o Contains enzymes that convert harmful products - tolerated or more easily removable ones Golgi Complex  Chemically modifies proteins made in Rough ER o Antibodies  Regulates the movement of several types of proteins o Secreted o Embedded in plasma membrane/lysosomes  Sorts finished proteins to be secreted form cell or embedded in plasma membrane  Located between ER and plasma membrane  Secretory Vesicles o Release contents to their exterior - exocytosis o Endocytosis - brings molecules into cell Vesicular Traffic: better understanding  Proteins made by ER ribosomes enter ER membranes or place inside ER o Chemical modifications o Lipids made  Vesicles bud from ER membrane - transport unfinished proteins and lipids to Golgi complex  Protein and lipid modification -products sorted into vesicles  Secretory vesicles transport finished products to plasma membrane  Lysosomes contain enzymes that digest damaged organelles Exocytosis and Endocytosis  Vesicles are responsible for transporting materials between compartments of the endomembrane system  Exocytosis o Secretory vesicles release their contents to the exterior o Vesicles fuse with plasma membrane + spills contents outside  Endocytosis o Brings molecules into the cell from the exterior  Plasma membrane forms pocket, pinches off cytoplasm as endocytic vesicle  Carried to the Golgi complex Mitochondria  Membrane bound organelles- cellular respiration takes place  Generates ATP  Occurs in cristae and matrix Mitochondria + Cytoplasm  Both surrounded by 2 membranes (outer and inner)  Both folded  Have DNA  Own ribosomes  Chloroplast - harnessing energy and storing sugars  Mitochondria - taking sugar and forming it into ATP Theory of Endosymbiosis  Mitochondria o Developed form ingested prokaryotes o Capable of using oxygen for aerobic respiration o Come from bacteria  Chloroplast o Ingested cyanobacteria o Come from photosynthesizing cyanobacteria Endosymbiont Hypothesis  Original prokaryotic host cell  Multiple ingestion of the plasma membrane o Aerobic bacteria is ingested  Bacteria became mitochondria o Nuclear envelope form from plasma membrane  Eukaryotic cell o Photosynthetic bacteria ingested - chloroplast + mitochondria o Cells without mitochondria - animals, fungi, protists Evidence to Support Endosymbiont  Morphology  Reproduction (division)  Genetic information  Transcription + Translation  Electron transport Peroxisomes  Eukaryotic organelle that is not apart of the endomembrane system  Site of biochemical pathway that generate hydrogen peroxide as a byproduct Cytoskeleton  Microtubules o Construct supportive structures o Microtubule polarity - different ends o Separating and moving chromosome during cell division o Growth of cell wall o Maintaining the shape of animal cells o Animal cells  Motor proteins that push or pull against micro muscles  Dyneins and kinesins  Intermediate filament o Found in multicellular organisms o Structural support in an many cells  Microfilament o Eukaryotic cells o Flowing motion of cytoplasm o Transport nutrients, proteins and organelles in animals and plants Defining Life and its Origins 10/9/2012 7:37:00 PM 7 Characteristics of Life  Display order o Arranged in a highly ordered manner  Harness and Utilize energy o All forms of life acquire energy from the environment use it to maintain their highly ordered state  Reproduce o Ability to make some of their own kind  Respond to stimuli o Make adjustments to their structure, function and behaviour in response to changes to the external environment  Exhibit Homeostasis o Able to regulate their internal environment such that conditions remain relatively constant o Sweating  Growth and development o Increase their size by increasing the size and number of cells  Evolve o Populations of living orga
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