Biology 1201 Exam 2 MaterialChapter 8: Chemical ReactionsPages 142-161I. Chemical Reactions:- When two or more atoms, ions, or molecules collide in such a way that they produce a newsubstance- They must physically hit each other hard enough to form something new All chemical reactions are governed by the following laws: - 1st - Energy can neither be created nor destroyed, only converted from one form to another- 2nd – When converting energy from one form to another, the amount of useful energy decreasesTypes of Chemical Reactions (Spontaneous versus Non-Spontaneous)Spontaneous reaction- Release free energy- Greater reactants than products- Can occur without outside help(Exergonic)Non-spontaneous reaction- Require free energy- Less reactants than products- Needs outside help or else it cannot occur (Endergonic)Free Energy (G)- Energy that is free and available to do useful work in the cell - In all spontaneous reactions: G- (free energy in systems)decreases = exergonic- In all non-spontaneous reactions: G+ increases =endergonico Exergonic releases free energyo Endergonic requires free energy - Equation: G = H-TS- G = Free Energy- H = enthalpy (the heat energy of the system, contained withinthe system)- T = Temperature (Kelvins)- S = entropy (a measure of disorder in a system, greaterdisorder = greater entropy)What happened during the reaction? (match and flame experiment)Biology 1201 Exam 2 Material- Heat energy was released - Entropy decreased X Entropy increased, enthalpy decreased- It was non-spontaneous X Spontaneous, High Activation Energy- The free energy increased X The Free energy decreased- More than one of the above XWhat happened during this reaction? (solution mixed in and beaker got cold)G = H - TSG decreasedH increased because Heat was not released T decreasedS increased- Heat energy was released X Heat energy was absorbed- Entropy increased Disorder increased- Spontaneous - Free energy increased X Enthalpy increased! Free energy decreasedo It can’t be spontaneous and have free energy!- More than one of the aboveWhich of the following reactions will always be spontaneous?- Enthalpy increases, entropy decreases- Enthalpy decreases, entropy decreases- Enthalpy increases, entropy increases- Enthalpy decreases, entropy increasesG = H - TSG decreases then H decreasesWhich of the following will always be a non-spontaneous reaction?- Enthalpy increases, entropy decreases- Enthalpy decreases, entropy decreases- Enthalpy increases, entropy increases- Enthalpy decreases, entropy increasesA spontaneous reactions occurring at 100 Kelvins and with a 250 Kcal increase in enthalpy, it musthave which of the following change in entropy?- 3.5 KcalG = H-TS- -G - Free energy decreases- H increases- S increasesA non-spontaneous reaction occurring at 200k with a 150Kcal decrease in enthalpy has which of the following changes in entropy? -1.0Kcal- In a non-spontaneous reaction, free energy will be required, positive free energy (increase)Biology 1201 Exam 2 Material- G will be positive- H will be negative- T = 200k- G = -150Kcal – 200K(S) A spontaneous reaction occurring at 200k with a 1.5kcal decrease in entropy has which of the following changes in enthalpy? -400KcalG will be negative, Temp = 200k, S=-1.5Kcal, Enthalpy will be negative G=H-(200K)(-1.5Kcal)II. Living vs. Non-living Systems: i. Nonliving Systemsa. Less organizedb. Low energyc. Very slowii. Living Systemsa. More organizedb. High energy c. FastHow do living things accomplish this?External Energy source – Living things require an external energy source for chemical reactions to occur- The sun is the main external source for living thingsSpeed – Organic Catalysts, EnzymesIII. Enzymes: - Almost all are proteins, NOT all of them - They are large, globular proteins that contain primary, secondary and tertiary structureo They may even have quaternary structurei. Function:- Organic Catalysts- Speed up the rate of a reaction, but not used up during the reaction- Very specificUsing the Diagram:Which line represents the activation energy for an uncatalysed reaction? Which represents the change in free energy?Which represents the activation energy for a catalyzed reaction?Biology 1201 Exam 2 MaterialInduced-Fit Model:- The substrate binds to the active site of the enzyme- This alters the shape of the enzyme (which is made up weak bonds, allows for change)- Creating or “induces” a fit that promotes the reaction (lowers the activation energy)o Example: Using a baseball mitt to catch a baseball squeeze the gloveWhat do the following have in common? They are enzyme inhibitors, which means they regulate enzymes- Roundup (Glyphosate)- Anti-bacterial hand soap (Triclosan)- Aleve (Naproxen Sodium)- Viagra (Sildenafil)a. Competitive Inhibition: - Inhibitor binds to the active site and blocks access to the active site- Some competitive inhibitors are removable and some are irreversible Example: toxins can be irreversible b. Noncompetitive Inhibition: - Inhibitor binds to a site other than the active site and alters the shape of the active site - The active site cannot fit the substratec. Allosteric Inhibition/Regulation: - Enzyme alternates between active and inactive forms - Inhibitor binds to a site other than the active site and stabilizes one shape of the enzyme (inactive site)Chapter 7: Membrane Structure and FunctionPages 125-141IV. Cells: the minimum organization of living mattera. Fluid-Mosaic Model: Phospholipid bilayer with a mosaic of associated proteins- The interior is nonpolarBiology 1201 Exam 2 Material- The exterior is polar- The heads are hydrophilic- The tails are hydrophobicClicker Questions:What is more likely to happen? Is it easier for adjacent heads to switch spots or for opposite heads/tails to switch spots on phospholipids?- It is easier for adjacent heads to switch places so that the hydrophobic tails do not come incontact with water- Adjacent heads will often switch places in systemsThe section of the integral protein that is within the phospholipid bilayer contains what kind of amino acids?- NonpolarThe peripheral protein contains what kind ofamino acids?- Polar amino acidsCell Coat: Outside of cell membraneComposition:o Glycolipids - attached tolipids (heads)o Glycoproteins – attached toproteins (peripheral) Function:o Cell recognition Why do cells have membranes?1.
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