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Date Created: 09/09/14
Bio 152 Exam 1 Review Sheet Week 1 Cell Membranes and How They Work Cell Membrane keeping the inside outside of a cell different composed of gt phospholipid has a polar head which is hydrophilic love water form weak bonds with water and a non polar tail which is hydrophobic hates water tend to get pushed together when around water since don t care about it the heads of the phospholipid make up the outside of the cell membrane while the tails make up the inside EX A non polar cell membrane protein will most likely be found entirely in the center of the membrane Types of Membrane Proteins 1 Peripheral Membrane Proteins polar outside bind to the membrane without passing through 2 Integral Membrane Proteins non polar polar goes in the middle Phospholipid Bilayer selective permeability smallnonpolar molecules get in easily large polar and ions get rejected Membrane Transport moving molecules across a cell membrane EX Molecules of the same type move in random speeds and directions when dissolved in liquid Diffusion the act of molecules moving at random speeds and directions diffusion of water molecules osmosis will not only go from high to low concentration but towards their opposite charge net ow depends on relative concentrations EX If a membrane is impermeable to glucose and you have water on the left and add glucose to the right what will happen gt the water level is going to go up on the glucose right side bc the water molecules move over to equalize the concentration of water but does not equalize volume Molecules with low permeability move through cell membranes by proteins that are specialized to move specific molecules form one side of the cell to the other Facilitated Diffusion relies on the random movement of molecules but also relies on the protein channels to move water through the membrane Gated Ion Channels gate blocks ions from entering the channel change shape to mediate diffusion and solutes move down the concentration gradient Carrier Proteins a type of protein that affects facilitated diffusion depend on their target molecule Bind to them and change their shape so they can open the channel and move down the concentration gradient Active Transport moving molecules against the concentration gradient requires input of energy Increases the concentration and charge difference between the inside and outside of a cell Amphipathic compounds that contain both hydrophobic and hydrophilic properties phospholipids Electrochemical Gradient ions move in response to a combined concentration and electrical gradient Week 2 Managing Multicellularity All plants and animals use transmembrane proteins to move ions in and out of their cells Specializing Cells animals and plants do this a cell will lose the ability to express anything other than the genes speci c to their own cell type gt differentiation EX How do organism get from totipotent capable of being any cell type to a differentiated cell gt some cells produce signal proteins that affect DNA expression in nearby cells gt changes in gene expression can induce cell movement cell death or the production of other signal proteins Differentiation differentiated cells contain the entire genome but express only a subset of genes evert specialized cell in an organism still contains the same genome Keeping Cells Together cell walls are glued together by pectins in the middle lamella membrane proteins called integrins bind to laminin proteins in the extracellular matrix Animals proteins intergrins anchor cell membranes to laminins laminin in the ECM cross link ECM proteins proteoglycans ECM amorphous matrix collagen ECM bers Plants sugars pectins glue cell walls to one another Tight Junctions form water tight seals between cells on apical side and are in direct contact with the outside environment weaker connection Desmosomes stronger connections between cell membranes Some connection proteins are very speci c to tissue type Gap Junction channel proteins direct cellcell communication transfer of small molecules membrane proteins form adjacent channels by lining up in both plants and animals Plasmodesmata plants form a gap junction extension of the smooth endoplasmic reticulum Composite Elements the stiff surrounding substance is effective at withstanding compression Cell Walls In Plants micro brils compose the primary cell wall space between micro brils lled with pectin hydrophilic so attract hold water to keep cells moist ECM in Animals extracellular matrix gt ber composite structural support collagen gt brous component of an animals ECM proteoglycans gt surrounds collagen consists of protein cores with polysaccharides Linkage between ECM and cytoskeleton vital bc it helps adjacent cells adhere to each other Cadherins provides the basis for selective adhesion During development in all organisms cells divide interact differentiate move or are programmed to die in a direct manner Clones look different bc express different genes Root System anchors the plant take in water and nutrients connected through vascular tissue Shoot System harvests light and CO2 to make sugar plants have high surface area to volume ratio repeating series of nodes intemodes leaves and apical and axillary buds size shape depend on environmental needs diversity plasticity and dynamism in plants the rate at which molecules and ions diffuse is dependent on the amount of surface area available and the volume of the animal for consumption as organisms size increases the amount of surface area available relative to that mass or volume is critical bc heat exchange and other important processes take place across surfaces Week 3 Structural Support and Force Transfer Size of an organism mass and energy are relative to volume absorption and the force of muscle contractions are relative to area Ratio of surface area to volume is used in organisms Area is length squared and volume is length cubed Muscles produce force by shortening and pulling on the skeletal elements attached to the ends The magnitude of force is proportional to the number of muscle brils inside the muscle Real organism make shape changes and proportion changes to adapt to size As animals get larger physiological rates slow down Hydrostatic Skeleton most common form of skeletons in animals basic form of a central mass of uid surrounded by a membrane that holds in tension interactions between pressurized uid and membrane in tension If a membrane is isotropic changes the intemal pressure because of hoop stress which is equal to 2 times the longitudinal stress Anisotropic Membrane reinforce the membrane with bers strong in tension Composite Materials in plants ber cellulose and ground pectin in animals ber collagen and ground proteoglycan Fibers in the ECM are highly organized around the uid space Reinforcing skeleton with crossedhelical bers affects the skeletal behavior gt can shorten elongate and bend easily When you add muscles skeleton can transmit forces to produce movement circumferential muscle and longitudinal muscle To move circumferential muscle contracts elongates and the longitudinal muscle relaxes shortens and then vice versa Speci c angle of bers relative to long axis of skeleton affects how body shape can change They also affect hoe the hydrostatic skeleton resists bending Vascular Tissue System functions in support and in long distance transport of Water and dissolved nutrients Smooth Muscle involuntary organized in thin sheets unbranched Cardiac Muscle makes up the Walls of the heart and is responsible for pumping blood throughout the body Skeletal Muscle consists of exceptionally long unbranched muscles bers Voluntary Slow Muscle Fibers go slow bc myosin hydrolyzes ATP at a slow rate Red Fast Muscle Fibers myosin hydrolyzes ATP at a rapid rate White Hydrostatic Skeleton extensible body Wall in tension surrounding a uid or deformable tissue under compression Week 4 Moving Molecules Around Fiber Arrangements on Graphs the stiffest type of skeleton would have the steepest slope The more exible the less steep of a slope hydrostat reinforced with fibers at 0 degrees and 90 degrees are very stiff Passive Force Transfer in Skeletons trees Trees reorient themselves in the Wind to reduce drag force on the leaves and to reduce the bending force on the trunk of the tree Animals Move by Generating Forces Intemally force production muscles force transfer lever system each muscle needs an antagonist force input from muscle produces change in a joint angle so output change in force and speed Force Transfer lever system gt in a lever system the moment on each side of the pivot point is the same Moment in terms of force F1L1 F2L2 Muscle Systems Velocity Advantage gt a small displacement on the input end produces a much larger displacement on output Displacements occur over the same time frame so output velocity distancetime is also larger than input velocity Lout Lin Muscle Behavior Can Be Affected By ber arrangements gt parallel aka fusiform small cross sections yet long length produces less force but displaces itself more pennate has large cross sections yet a short length produces more force but can displace itself less bc can t shorten much Seen alot in insect legs Exchange and Bulk Flow exchange of respiratory gases food and wastes across a cell membrane by diffusion diffusion is ineffective when moving a molecules long distances Solution to Slowness of Diffusion stay small or thin or have a bulk ow system Bulk Flow uid carries dissolved molecules and pressure difference move uid gtadvection Whats a Fluid 2 does not resist deformation under sheer stress takes on the shape of the container EX Water air Bulk Flow In Plants moving Water to roots and leaves is the goal in vascular plants Water moves through xylem takes advantage of difference in Water potential between the top and bottom of a plant Water Potential the potential energy of Water compared to the potential energy of pure Water at 20 degrees C and 1 atm 2 Variables solute potential gt energy produced by differences in solute concentration high concentration of solutes low Water potential pressure potential gt energy produced by physical pressure on the water positive water potential compression negative water potential tension Water potential solute potential pressure potential Water always ows from areas of high water potential to low water potential High Concentration of Solutes solute potential lt O Positive Pressure pressure potential gt O Negative Pressure pressure potential lt O EX Why does water enter a plants roots gt root cells have lower water potential because they contain more solutes than the water in the soil Xylem does not contain living cells therefore the difference in water potential that moves water up the plant must come from changes in pressure Turgor Pressure pressure inside the cell Turgid cells that are firm and experience wall pressure Wall Pressure force exerted by the wall Apoplast consists of cell walls which are porous and the spaces that exist between cells Symplast consists of the cytosol and the continuous connections through cells that exist via plasmodesmata Casparian Strip a narrow band of wax secreted Countercurrent Exchange in animals any anatomical arrangement that allows the maximum transfer of heat or a soluble substance from one uid to another Ficks Law Of Diffusion a mathematical relationship that describes the rates of diffusion of gases
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