2nd Bio Exam Study Guide-
2nd Bio Exam Study Guide- 110
University of Louisiana at Lafayette
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This 14 page Study Guide was uploaded by Antonio Cannet on Wednesday March 2, 2016. The Study Guide belongs to 110 at University of Louisiana at Lafayette taught by Dr. Kreyeski in Winter 2016. Since its upload, it has received 46 views. For similar materials see Fund of Biology I in Biology at University of Louisiana at Lafayette.
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Date Created: 03/02/16
CH 5 Biological Membranes Basic framework of the membrane is the phospholipid bilayer Membranes also contain proteins and carbohydrates Phospholipids Are amphipathic molecule Hydrophobic region faces in Hydrophilic region faces out Fluidmosaic model Membrane is considered a mosaic of lipid, protein, and carbohydrate molecules =Membrane exhibits properties that resemble a fluid because lipids and proteins can move relative to each other within the membrane Peripheral proteins The proteins of a membrane that are not embedded in the phospholipid bilayer; they are appendages loosely bound to the surface of the membrane. Electron microscopy Transmission electron microscopy (TEM), uses a biological sample that is thin sectioned and stained with heavymetal dyes Dye binds tightly to the polar head groups of phospholipids, but it does not bind well to the fatty acyl chains FFEM Freeze fracture electron microscopy, specialized form of TEM, can be used to analyze the interiors of phospholipid bilayers >Sample is frozen in liquid nitrogen and fractured with a knife >Due to the weakness of the central membrane region, the leaflets separate into a P face (the protoplasmic face that was next to the cytosol) and the E face (the extracellular face) >Can provide significant threedimensional detail about membrane protein form and shape Integral Membrane Proteins Transmembrane proteins >one of more regions that are physically embedded in the hydrophobic region of the phospholipid bilayer 1 Lipid Anchors >Covalent attachment of a lipid to an amino acid side chain within a protein Peripheral Membrane Proteins Noncovalently bound to regions of integral membrane proteins that project out from the membrane, or they are bound to the polar head groups of phospholipids Cholesterol A lipid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids. Estimated percentage of membrane proteins is substantial: 2030% of all genes may encode membrane proteins Fluidity individual molecules remain in close association yet have the ability to readily move within the membrane Semifluid Most lipids can rotate freely around their long axes and move laterally within the membrane leaflet Flippase Protein that facilitates the movement of membrane lipids from one leaflet to the other leaflet of a phospholipid bilayer Factors affecting fluidity Length of fatty acyl tails >Shorter acyl tails are less likely to interact, which makes the membrane more fluid Presence of double bonds in the acyl tails >Double bond creates a kink in the fatty acyl tail, making it more difficult for neighboring tails to interact and making the bilayer more fluid Presence of cholesterol >Cholesterol tends to stabilize membranes >Effects depend on temperature Glycocalyx A polysaccharide protective coating outside of the bacterial cell wall that is called either a capsule or slime layer based on its structure. 2 Glycolipid Carbohydrate to lipid Glycoprotein Carbohydrate to protein Cell coat or glycocalyx Carbohydraterich zone on the cell surface shielding cell Selectively permeable Structure ensures: >Essential molecules enter >metabolic intermediates remain >Waste products exit Hypertonic Having a higher concentration of solute than another solution. Isotonic Having the same solute concentration as another solution. Hypotonic Having a lower concentration of solute than another solution Crenation Shrinking in a hypertonic solution Describe lipid synthesis and where it takes placeto being the process of phospholipid synthesis, the fatty acids are activated by attachment to an organic molecule called coenzyme (CoA). This activation promotes the bonding of the two fatty acids to a glycerolphosphate molecule, and the resulting molecule is inserted into the cytosolic leaflet of the ER membrane Diffusion > Movement of solute from an area of higher concentration to an area of lower concentration > Passive diffusion: without transport protein Transmembrane gradient Concentration of a solute is higher on one side of a membrane than the other Ion electrochemical gradient Both an electrical gradient and chemical gradient 3 Passive transport Passive transport does not require an input of energy 2 types: >passive diffusion: diffusion of a solute through a membrane with transport protein > facilitated diffusion: diffusion of a solute through a membrane with the aid of a transport protein Osmosis Diffusion of water through a semipermeable membrane Water diffuses through a membrane from an area with more water to an area with less water If the solutes cannot move, water movement can make the cell shrink or swell as water leaves or enter the cell What does cell wall prevent? Major changes in cell size Osmotic pressure the tendency for water to move into any cell Turgor pressure Pushes plasma membrane against cell wall >Maintains shape and size PlasmolysisPlants wilt because water leaves plant cells Transport proteins Transport proteins enable biological membranes to be selectively permeable 2 Classes: >Channels (often passive; do not use energy) >Transporters Transporters Also known as carriers Principal pathway for the uptake of organic molecules, such as sugars, amino acids, and nucleotides Key role in import and export Channels Form an open passageway for the first diffusion of ions or molecules across the membrane 4 When a channel is open, a solute directly diffuses through the channel to reach the other side of the membrane Phosphorylation The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation. Uninporters Single molecule or ion Symportersmove two or more ions or molecules in the same direction across the membrane Antiportersexchange one or more ions or molecules for another ion or molecule across the membrane Active transport Movement of a solute across a membrane against it gradient from a region of low concentration to high concentration Primary active transport: direct use energy to transport solute Secondary active transport: Use preexisting gradient to drive transport of solute PumpCouples conformational changes to an energy source, such as ATP driven pumps Protein pump A protein in the membrane that uses energy to move things from low concentration to high concentration ATPdriven pumps ATP hydrolysis can be uriporters, symporters, or anti porters Active transport 5 Exocytosis A process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane. EndocytosisPlasma membrane folds inward to form a vesicle that brings substances into the cell Ch 6 & 7 The first law of thermodynamics: >Law of conservation of energy >Energy cannot be created nor destroyed Ex: Chemical energy is transformed into heat The second law of thermodynamic > Transfer or transformation of energy from one form to another increases entropy or degree of disorder of a system >Disorder (entropy) increases > Biological processes are not 100% efficient Ex: A chemical reaction may release unusable heat Energy ability to promote change; (the capacity to do work, including changing one molecule into another molecule) Kinetic energy Associated with movement Ex: the movement of a baseball bat from one location to another Potential energy The energy that an object has due to structure or location Entropy A measure of the disorder that cannot be harnessed to do work Enthalpy The heat content of a system at constant pressure Free energy The amount of available energy that can be used to promote or do work Exergonic >Negative free energy change > Spontaneous 6 Endergonic > Positive free energy change > Requires addition of free energy > Not spontaneous Delta G Change in free energy ATP A molecule that is a common energy source for all cells. Activation energy > Initial input of energy to start reaction > Allows molecules to get close enough to cause bond rearrangement > Can now achieve transition state where bonds are stretched Active site Location where reaction takes place Substrate Reactants that bind to active site Allosteric site A site on an enzyme other than the active site, to which a specific substance binds, thereby changing the shape and activity of the enzyme. What is an enzyme and what does it do? Enzymes are often proteins( but they can be ribozymes) and are the most common catalyst Catalyst agent that speeds up the rate of a chemical reaction without being consumed during the reaction Explain competitive and noncompetitive enzymes Biochemical regulation >Competitive inhibitors: compete for access to an enzyme's active site > Noncompetitive inhibitors: bind outside the active site [Slide 36] Describe a metabolic pathway (in general). How are enzymes involved? Chemical reactions occur in metabolic pathways Each step is coordinated by a specific enzyme > Result in breakdown and are exergonic Anabolic pathways > Promote synthesis and are endergonic > Must be coupled to exergonic reaction 7 Describe a redox or oxidation reduction reaction. Oxidation > Removal of elections Reduction > Addition of electrons Redox > Electron removed from one molecule is added to another Substrate Level phosphorylation > Enzyme directly transfers phosphate from one molecule to another molecule > Oxygen not needed Chemiosmosis > Energy stored in an electrochemical gradient is used to make ATP from ADP and Pi > Oxygen required Cellular respiration Process by which living cells obtain energy from organic molecules Primary aim to make ATP and NADH Aerobic respiration uses oxygen > O2 consumed and CO2 released Glucose metabolism 4 metabolic pathways 1. Glycolysis 2. Breakdown of pyruvate to an acetyl group 3. Citric acid cycle 4. Oxidative phosphorylation *Electron transport chain and chemiosmosis Stage 1: Glycolysis Glycolysis can occur with or without oxygen and it occurs in the cytoplasm Steps in glycolysis nearly identical in all living species 10 steps in 3 phases 1. Energy investment 2. Cleavage 3. Energy liberation 3 phases of glycolysis 1. Energy investment Steps 13 8 2 ATP hydrolyzed to create fructoses 2. Cleavage Steps 45 6 carbon molecule broken into two 3 carbon molecules of glyceraldehyde3 phosphate 3. Energy liberation Steps 610 Two glyceraldehyde3phosphate molecules broken down into two pyruvate moles producing 2 NADH and 4 ATP Stage 2: Breakdown of pyruvate to an acetyl groupIn eukaryotes, pyruvate in transported to the mitochondrial matrix Broken down by pyruvate dehydrogenase Molecule of CO2 removed from each pyruvate Remaining acetyl group attached to CoA to make acetyl CoA Stage 3: Citric acid cycle Metabolic cycle >Particular molecules enter while other leave, involving a series of organic molecules regenerated with each cycle Acetyl is removed from Acetyl CoA and attached to oxaloacetate to form citrate or citric acid Series of steps releases 2CO2, 1ATP, 3NADH, and 1 FADH2 Oxaloacetate is regenerated to start the cycle again Stage 4: Oxidative phosphorylation High energy electrons removed from NADH and FADH2 to make ATP Typically requires oxygen Oxidative process involves electron transport chain Phosphorylation occurs by ATP synthase Electron transport chain Group of protein complexes and small organic molecules embedded in the inner mitcohondrial membrane Can accept and donate electrons in a linear manner in a series of redox reactions Movement of electrons generates H+ electrochemical gradient/ protonmotive force >Excess of positive charge outside of matrix 9 Free energy change Movement from NADH to O2 is a very negative free energy change >Spontaneous in forward direction Highly exergonic Some energy used to pump H+ across inner mitochondrial membrane and create H+ electrochemical gradient ATP synthase Enzyme harnesses free energy as H+ flow through membrane embedded region Energy conversion H+ electrochemical gradient or proton motive force converted to chemical bond energy in ATP Racker and Stoeckenius confirmed ATP uses an H+ electrochemical gradient Rotary machine that makes ATP as it spins Anaerobic metabolism For environments that lack oxygen or during oxygen deficits 2 strategies >Use substance other than O2 as final electron acceptor in electron transport chain >If confined to using O2, carry out glycolysis only >Pyruvate converted to lactate or lactic acid in muscles or ethanol is yeast >Fermentation produces far less ATP Secondary Metabolism Primary metabolism essential for cell structure and function Secondary metabolism synthesis of secondary metabolites that are not necessary for cell structure and growth Secondary metabolites unique to a species or group Roles in defense, attraction, protection, competition 4 categories Phenolics >Antioxidants with intense flavors and smells Alkaloids Bittertasting molecules for defense Terpenoids >Intense smells and colors Polyketides >Chemical weapons 10 CH 7 QUESTIONS How many ATP do you get in a eukaryotic cell when oxygen is present? 36 Where in the prokaryote does the citric acid cycle (CAC) take place? Cytoplasm What molecule is limiting in fermentation? NAD+ What process forms ATP during fermentation? Glycolysis What happens to pyruvate during fermentation? What happens to it during cellular respiration? During fermentation, pyruvate is reduced, and during cellular respiration it is oxidized How many NADH do you get from the citric acid cycle (CAC) per pyruvate? What about per glucose? 3 per pyruvate and 6 per glucose How many carbon dioxide molecules are created during CAC? Where did they come from? Four molecules of CO2 all together. They came from glucose What is the proton motive force? Where can it be found? It is a high concentration of hydrogen ions. It is found between the inner and outer membranes of the mitochondria, or the inner mitochondrial space What molecule does FADH2 donate its electrons to? FADH2 donates its' electrons to succinate, therefore only allowing 2h+ to be pumped into the electron motive force How many ATP are formed as the result of electrons carried by NADH? What about FADH2? 3 ATP per NADH and 2 ATP per FADH2 What molecule cycles in the CAC? Oxaloacetate Why do we breathe? Oxygen is required to pull electrons through the electron transport chain. This is necessary for primary metabolism to function. Primary metabolism provides the cells with ATP, which is required for a cell to live (avoid entropy) 11 Can animal cells ferment? When they do what molecule builds up? Where does that molecule come from (what is the reaction)? Yes, animal cells fermeuntate when oxygen is not present. They produce lactic acid as the result of fermentation. This builds up in the cells. Latin acid is produced the pyruvate is reduced directly How many ATP are formed during glycolysis? Gross? Net? Glycolysis makes 4 ATP, however 2 are used at the beginning of the process, meaning only two can be used. 4=gross; 2=net Name the three integral proteins of the electron transport chain (also known as the respiratory chain)?NADH dehydrogenase, cytochrome BC1; Cytochrome oxydase What is chemiosmosis? What is the protein complex involved? It is the production of AP by ATPsynapse. When hydrogen travels down the concentration gradient (from the intermitocondrial space to the matrix of the mitochondria) ATPsynthase spins. This produces ATP. What is oxidative phosphorylation? Cellular respiration without glycolysis What is substrate phosphorylation? Adding high energy phosphates to a molecule What is GTP and in what prices is it found? Guanine triphosphate... It is found in the CAC Account for all of the water that is produced as byproducts of breaking down sugar during cellular respiration. (remember to check all of the processes involved) Water is produced in step 9 of glycolysis. Water is produced at the end of the electron transport chain when oxygen accepts electrons. Hydrogen is attracted to the oxygen and water is formed CH 40 12 Organization of Animal Bodies All animal cells share similarities in the ways in which they: Exhange materials with their surroundings Obtain energy from organic nutrients Synthesize complex molecules Reproduce themselves Detect and respond to signals in their immediate environment Vertebrate Tissues Specialized cells of a given type cluster together > Muscle Tissue > Nervous Tissue > Epithelial Tissue > Connective Tissue Muscle Tissue Most abundant tissue 3 types of muscle tissue >Skeletal Muscle >Smooth Muscle >Cardiac Muscle Skeletal Muscle Attached to bone or exoskeleton, voluntary control, striated, multi nucleated Smooth Muscle Surrounds tubes and cavities for propulsion of contents, involuntary control, not striated Cardiac Muscle Only in the heart, involuntary control, striated Nervous tissue Initiate and conduct electrical signals from one part of the animal's body to another Single nerve cell called a neuron Electrical signals produced in a nerve cell may stimulate or inhibit other cells to: >Initiate new action potentials in other neurons >Stimulate muscle to contract >Stimulate glands to release chemicals Epithelial tissues Sheets of denselypacked cells that: 13 >Cover the body or enclose organs > Line the walls of body cavities Specialized to protect and secrete or absorb All are asymmetrical or polarized >Rest on basal lamina or basement membrane Can function as selective barriers Connective tissues Most diverse tissue Connect, anchor, and support Includes blood, adipose, bone, cartilage, loose and dense connective tissue (ligaments and tendons) Form extracellular matrix around cells > Provides scaffold for attachment > Protects and cushions >Mechanical strength > Transmit information Organs Composed of multiple tissues Organ system: different organs work together to perform an overall function Organ systems frequently work together nervous and endocrine system Spatial arrangement of organs into organ systems part of overall body plan Body plan controlled by highly conserved family of genes with homologs in all anim als 14
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