Comparative Physiology Test 1 Study Guide
Comparative Physiology Test 1 Study Guide Biology 321
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This 10 page Study Guide was uploaded by Lauren Notetaker on Thursday September 8, 2016. The Study Guide belongs to Biology 321 at College of Charleston taught by Dr. Meyer-Bernstein in Fall 2016. Since its upload, it has received 21 views. For similar materials see Comparative Physiology in Biology at College of Charleston.
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Date Created: 09/08/16
General and Comparative Physiology Study Guide – Test 1 UNIT 1 What is physiology? o How “things” work – functions & mechanisms o Some subdivisions include cell, developmental, comparative, etc. Systems physiology – processes like respiration, breathing Integrative physiology – how does one level of a system affect another? Cellular level vs. organ system level Pathophysiology – how diseases can effect a system Comparative – discern physiological & evolutionary patterns o Physiology is important, because it is biologically integrative o Form dictates function – has to do with chemistry, physics, ecology, behavior, anatomy, etc. What does an organism’s ability to maintain certain temperature depend on? o Needs a way to detect a change in body temperature o Needs ability to insulate and sweat – heat and cool own body o Needs to control rate of heat production o Needs an environmental temperature to respond to o All of these allow organisms to react and live in their environment. Bioluminescence – firefly example o Luciferin + ATP + O =2electron-excited product o Excited product + firefly luciferase = photons + ground- state product o Why do they flash? In Dark State, oxygen comes into the cell near the mitochondria & oxygen is absorbed by the mitochondria In Flashing State, nitric oxide prevents mitochondria from absorbing O 2 oxygen is free to interact with the luciferin reaction Fireflies flash for mating – selection pressures make flashing useful The salmon example – salmon go from saltwater to freshwater to lay their eggs o In saltwater, fish must work to counteract salinity and in freshwater they must work to maintain a higher salinity – how can salmon switch between the two? o They must use different proteins for their different environments, which ends up being a huge energetic cost The importance of animal physiology: o Scientific curiosity! De Marian (1730’s) – said that Circadian rhythms are governed internally and not by the time of day Studied mimosa flowers and put them in a closet – noticed that even without light, they maintained their circadian rhythm Circadian rhythm allows different chemical peaks at different time – advantageous, because it won’t let two important chemicals inhibit each other if they are released at different times o Practical applications Leads to insights into human physiology – many processes in other animals are similar to those in humans Foundation for treatment of human disease August Krogh Principle – for many problems, there is an animal that can be conveniently studied The squid has a body-long axon that made it possible for Hodgkin & Huxley (1950’s) to study the external physiology when the technology was not available for them to study smaller nerve cells Very applicable to human neuron studies! Conformers vs. Regulators o Conformers parallel internal environment with external environment to a degree, while regulators maintain homeostasis o Regulators have a zone of stability – euryhaline (wide range) & stenohaline (small range) o Conformers have little flexibility with types of environments they can live in Homeostasis – tendency for an organism to maintain constant internal environment relative to external environment – comes at a high energetic cost o Claude Bernard – founder of physiology, first documented homeostasis in insulin/glucagon cycle o Walter Cannon – coined the term homeostasis Additional Vocab: o Adaptation – by natural selection (over generations), a trait has evolved and is irreversible o Acclimatization – chronic exposure leading to a change (with naturally-occurring environmental conditions) o Acclimation – acclimatization, but in the lab Acclimatization and acclimation are generally reversible (changing altitudes and lung ventilation rate) o Adaptive value – in context of traits, if it is high frequency in a population and ensures a high probability of survival o Negative feedback – fluctuation in one direction causes feedback that causes response in the opposite direction – signal inversion o Positive feedback – no signal inversion, variable continues to increase (giving birth, vomiting, swallowing) Hodgkin Cycle – sodium channels open for depolarization – leads to action potentials o Hypotonic – something has less of a variable than what it is being compared to o Hypertonic – something has more of a variable than what it is being compared to o Reductionism – studying very specific pieces of a system o Genetic engineering – manipulating genetic material of an organism – inserting DNA fragment into cloning vector – recombinant DNA – functional gene produces important molecules that can treat diseases like cystic fibrosis and autoimmune diseases o Transgenic animals – have parts of DNA from another organism UNIT 2 Energy o Energy metabolism is the ability to cause specific changes in the body, need energy to do work – the body is an open system (we lose and gain energy from our environment) o Chemical energy – maintaining cells, energy from food o Electrical energy – maintaining potentials o Mechanical energy – any movement, down to the flagella o Thermal energy – mostly goes into keeping temp. constant o Molecular energy – more to do with chemistry Equilibrium Constant C [D] o For the reaction, A + B -> C + D, K eq= [ ]B] o This is theoretical, since not possible in open system o Spontaneous reaction More product than reactant K’eq is a large number ΔG is negative Exergonic reaction – releases energy o Nonspontaneous reaction More reactant than product K’eq is a small number ΔG is positive Endergonic reaction – requires energy o ΔG=−RTlnK 'eq Gibbs Free Energy (ΔG) o this is the energy available to do work o ΔG = ΔH – TΔS, where H is enthalpy (heat exchange) and S is entropy (disorder) o For a spontaneous reaction, entropy (S) must increase What determines reaction rate? o All depends on the needs of the organism o Law of Mass Action – higher concentration of reactant = faster reaction o Activation energy (ΔG*)– can be as small as the collision of molecules, but if the activation energy is a high value, it will likely be a slow reaction Enzymes help get over activation energies o Temp – need the “sweet spot” for the reaction, the higher the temp, the faster the reaction until you get too hot and the proteins denature o Catalysts – nearly all biological reactions are mediated by catalysts – enzymes are biological catalysts Hydrolase – hydrolytic cleavage reaction Protease – break down proteins Synthase – synthesize molecules Kinase – adds a phosphate group Phosphatase – removes a phosphate group ATPase – hydrolyzes ATP How do enzymes work? o Make reactions happen/accelerate by lowering E (actavation energy) Can’t change ΔG, K’eq, or favorability of reaction o Uses enzyme-substrate complex (ES) Enzymes are fairly specific about which substrates they interact with – must have affinity for substrate – active sites are fit for specific substrates, whether it be by size or charge, etc. o E+S↔ES→EP→E+P o enzyme is regenerated after reaction – can react with substrate again o absolute specificity – enzyme will only catalyze one type of reaction ex. Acetylcholinesterase only catalyzes transfer of acetyl choline o group specificity – will catalyze reactions involving a certain molecule ex. Alcohol dehydrogenase facilitates conversion of alcohols to ketones/aldehydes o linkage specificity – will catalyze reactions involving certain bonds o turnover number – representative of catalytic activity – number of reactions per second by an enzyme Enzyme Kinetics o Vmax – the point at which the enzyme is saturated with substrate – the fastest the reaction will take place at those conditions o Km – inversely proportional to affinity that an enzyme has for a substrate – also is the concentration of substrate at half of Vmax o this graph is representative of the change in initial velocity for increasing amounts of substrate o zero-order kinetics – enzyme is saturated with substrate – enzymatic reaction independent of substrate concentration o first-order kinetics – enzymatic reaction depends on concentration of one substrate o second-order kinetics – enzymatic reaction depends on more than one substrate o Michaelis-Menten Equation [S] v0=V max [ ]+K m o Lineweaver-Burk Equation the inverse of the M-M equation 1 K m 1 = + v0 V maxS] V max Regulating activity of enzymes o Reactions in the body usually involve several substrates, intermediates, and enzymes, where if one enzyme doesn’t work, the chain of reactions is likely to change or not take place o In the lab, we can vary the temperature and pH to affect the activity of enzymes, but organisms cannot actively do this to themselves There is an optimal temp for kinetic energy in reaction, but can’t be too high – denaturing proteins Residues within the active site have to be protonated/deprotonated to react with substrate – pH affects this o Active regulation – how an organism regulates enzymatic activity – by synthesis of new enzymes, inhibitors, regulators, post-translational modification, etc. o Inducible enzymes – enzymes aren’t made until they are needed and are normally at very low levels Ex. Pollution introduces halogenated hydrocarbons – these compounds act as transcription factors to trigger transcription of cytochrome P450 oxidases to combat pollution problem o Inhibitors – molecules that reduce the rate of enzymatic activity Competitive – inhibitors are substrate analogs (look- alikes) that compete with substrate for enzyme’s active site – block substrate from binding and from reaction taking place – increases Km Noncompetitive – binds to enzyme other than active site to reduce enzymatic activity can bind to enzyme or enzyme-substrate complex (ES) Vmax reduced, no change in Km – doesn’t change the affinity an enzyme has for the substrate Mixed inhibitor – same as noncompetitive, but can induce a conformational change in enzyme that reduces activity Increases Km and decreases Vmax o Post-translational modification Phosphorylation is the most common – can make enzyme activate or inactivate (like a light switch) Some systems are activated by cascade of phosphorylation of enzymes to enzymes to eventually a product o Allostery – enzymes often have many allosteric sites for inhibitors and activators alike Membrane Physiology o Primarily made of lipids (tons of different kinds), proteins (a lot for transport and signaling) and carbohydrates (get in between the lipids) Integral proteins live within the membrane and can act as transport channels for specific/general molecules o Fluid Mosaic Model – Singer & Nicolson (1972) – said that the membrane is very fluid, constantly moving and that it is nonhomogeneous – positions of parts and proteins are not static – proteins can freely move laterally through the membrane o Functions of a membrane – can act as a barrier between external and internal environment, as a regulator (controlling what is exchanged between cell and environment), communicator (responds to changes in environment), or simply a structural support for the cell Membranes maintain concentration gradients and potentials o Permeability – movement across a membrane – dependent on temperature (directly proportional), lipid type (PE – more unsaturated – more fluidity: PC – less unsaturated – less fluidity), degree of saturation Amount of cholesterol can be changed – with a constant level of cholesterol, high temperatures decrease flexibility of membrane and low temperatures increase flexibility of membrane Fish that live in very cold waters have high levels of cholesterol to maintain fluidity in their cell membranes Permeability can be changed for any given substance – can add or take away transport proteins for anything CO 2 N 2 O2, urea and ethanol pass through the membrane without much problem, water can sometimes pass through the membrane Large, uncharged polar molecules, ions, and charged, polar molecules do not pass freely through the membrane, must be helped in by a protein UNIT 3 Transport o Passive/simple diffusion – no energy required, moves substances towards equilibrium Molecule must break all hydrogen bonds with water molecules in order to pass through the lipid bilayer – must break bonds on their own – must be high enough in energy o Passive transport/facilitated diffusion – no energy required, moves substances towards equilibrium, required mediating molecule (protein) Can mask electrical properties of a molecule, letting it pass through membrane Uniporter – moves solute one direction across membrane Coupled transport – moves two different solutes across membrane Symporter – moves two molecules the same direction across membrane Antiporter – moves two molecules in opposite directions across membrane o Active transport – energy required (usually ATP), moves against gradient/potential, requires a mediating molecule Na+/K+ pump – ATPase that transports Na+ out of the cell and K+ into the cell – combats sodium leakage into the cell by continuously pumping sodium out of the cell Generates net charge across the membrane – rheogenic If there is enough current to effect voltage across the membrane, then it is electrogenic o Osmosis – movement of water across a concentration gradient – causes hydrostatic pressure o Endocytosis – cell takes in molecules – pinocytosis (liquids) – phagocytosis (solids) Receptor-mediated endocytosis – receptor on outside of cell that binds to ligand/virus/etc. – causes invagination of cell membrane and travels to destination within the cytosol o Exocytosis – macromolecules secreted from cell – prime example is the nervous system – neurotransmitters are secreted from the nerve terminal membrane Creation of excess membrane is fixed by membrane recycling – cell is making vesicles out of membrane (endocytosis) 2+ Exocytosis is stimulated by increases levels of Ca within the cell Gap junction – opening between two adjacent cells that allows flow of water soluble molecules and inorganic ions from one cytosol to the other – takes the form of six hexagonal subunits that stretch from one cell to the other – close with increase of calcium or hydrogen ions within the cell Tight junctions – seal adjacent cells together without any channels – sometimes looks like thin bands of proteins wrapped around cells (zonula occulens) o Makes molecules pass through cell (transcellular pathway) instead of around the cells (paracellular pathway) o Desmosomes(zonula adherens) – structural bonding for neighboring cells o Epithelial cells are linked heavily by tight junctions o Ussing chamber – experiment to observe Na+ transport across epithelial cells (used patch of frog skin) – showed that Na+ moves passively from the mucosal side of the cell to the inside of the cell, once inside the cell, it is actively pumped out on the serosal side of the cell (past the epithelial wall of cells) Additional Vocab: o Anabolic – synthesis, build molecules o Catabolic – break down molecules o Electrolytes – salts/acids/bases that ionize in solution and increase conductivity o Nonelectrolytes – sugars/alcohols/oils do not increase conductivity o Solvation/hydration – clustering of water molecules around ions/polar molecules o Amphipathic molecules – contain polar and nonpolar groups – phospholipids contain nonpolar fatty acid chains and polar head o Amphoteric – can act as acid or base – water and amino acids are amphoteric o Isoelectric point – pH at which net charge of amino acid is zero o HSP – heat shock proteins – chaperones that protect proteins in stress of high temperatures o Cofactors – small molecules that aid enzymes (vitamins & metal ions) o Coenzymes – small organic molecules that aid an enzyme (NAD+)
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