APK 2105C Study Guide - Quiz Guide: Atp Hydrolysis, Cell Metabolism, Kinetic Energy
23 May 2018
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Cell Metabolism All Lectures
Lecture 1
Chapter 3, Part 1
Cell Metabolism
• Cell metabolism
o Metabolism = sum total of all chemical rxns that occur in cells
o Energy metabolism = rxns involved in energy storage and use
• Chemical rxns 101
o New bonds form and old bonds are broken
o Total mass of reactants equals the total mass of the products
o One sided arrow = net direction of reaction is going that way
• Types of metabolic rxns
o Anabolic = produces larger molecules from smaller reactants
▪ Amino acids → proteins
▪ Glucose → glycogen
o Catabolic = breakdown of larger molecules into smaller products
▪ Glycogen → glucose
▪ Protein → amino acids
o Energy is associated with both of these types of rxns
• Metabolic pathways
o Most metabolic rxns are series of reactions
o Initial reactants → intermediates → end-products
▪ Intermediates may play role in feedback
• Hydrolysis and condensation rxns
o Hydrolysis = splitting with water
▪ A—B + H2O → A—OH + H—B
• Water molecule in reactant side of equation
▪ Sucrose + H2O → glucose + fructose
▪ Catabolic
o Condensation = water forming
▪ A—OH + H—B → A—B + H2O
• Water molecule in product side of equation
▪ Glucose + fructose → sucrose + H2O
▪ Anabolic
o Phosphorylation = addition of a phosphate group
▪ A + Pi (inorganic)→ A—P
▪ ADP + Pi → ATP + H2O (condensation)
o Dephosphorylation = removal of a P group
▪ A—P → A + Pi
▪ ATP + H2O → ADP + Pi (hydrolysis)
• Oxidation-reduction rxns
o Oxidation = removal (losing) of electrons (LEO)
▪ H2 → 2H+ + 2e-
▪ Electrons were removed from this reactant, resulting in formation of an
ion product
o Reduction = acceptance (gaining) of electrons (GER)
▪ H2+ + 2e- → H2
▪ Electrons combine with ions to form uncharged atoms
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o HA—BH → A=B + 2H (oxidation)
▪ Hydrogen atoms were removed
▪ Even though H atoms were removed—not e—the rxn is still oxidation
because each H atom carries an e-
▪ H atoms (not ions) = reducing equivalents
▪ Look for removal of H—not just the removal of e-
Lecture 2
Chapter 3, Part 2
Cell Metabolism
• Work and energy
o Energy = capacity to perform work
▪ Types of energy
• Kinetic energy = energy associated with matter in motion
o Molecules have kinetic energy because they move/vibrate
randomly at any temp above absolute 0
• Potential energy = energy stored in matter than can become
kinetic energy
o Bonds between atoms contain potential energy because
they can be broken to release more energy
o Examples of work in the body
▪ Movement
▪ Urine production (pump ions in certain directions)
▪ Cellular repair and reproduction
▪ Exocytosis of neurotransmitters from axons
o All work is driven by metabolic rxns
• Laws of thermodynamics
o First law = energy can neither be created nor destroyed—just converted from one
type to another
o Second law = natural processes tend to process in the direction that spreads
energy
▪ Example: diffusion of soln from high conc to low conc
• Energy change
o All chemical rxns involve energy exchange
▪ Due to 1st law of thermodynamics—have to have same amount of energy
on both sides of the equation
▪ Molecules possess energy
▪ If a rxn releases energy it’s because the reactant molecules had more
energy than the products
• Reactants → products + energy
▪ Released energy can sometimes be used to do work
▪ Change in energy determines the direction of a reaction
o Change of energy = energy of products – energy of reactants
▪ Exergonic reactions
• Proceed spontaneously
• Release energy
• Delta E (change in energy) is negative
• Energy EXITS the reaction
• Products have less energy than reactants
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▪ Endergonic reactions
• Do NOT process spontaneously
• Reactants have less energy than the
products
• Have to add energy to the system for the rxn
to proceed
• deltaE is positive
▪ Commonly expressed in units of energy/unit of mass
(ex: kcal/mol)
• Calories (cal) or kilocalories (kcal)
o calorie = amt of energy/heat necessary to raise the
temperature of 1g of water by 1 degree C
▪ Releases energy as heat
▪ Usually when measuring energy of rxn, measure
heat
• Joules (J) or kilojoules (kJ)
▪ Nature of reactants/products (which has more initial E?) is important but
quantity (amt starting with) also matters
▪ Exergonic-endergonic coupling
• Energy released from catabolic rxns is used to drive anabolic rxns
• Taking rxn that releases energy and capturing some of that
energy to drive an endergonic rxn that requires energy to proceed
• In the human body we cannot capture all the released energy—
some is released as heat
Lecture 3
Chapter 3, Part 3
Cell Metabolism
• Equilibrium = reactant is converted to product at the same rate that the product is
converted to the reactant
o Energy is equal on both sides of the equation
o deltaE = 0
o [reactant] does NOT = [product]
o If the E difference is large between the reactants and products—conc difference
at equilibrium will also be large
▪ If the energy per mole of the reactants (2
kcal/mol) is greater than that of the products
(1 kcal/mole), at equilibrium there will be
greater conc of products
• The law of mass action
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find more resources at oneclass.com
Document Summary
In the human body we cannot capture all the released energy some is released as heat. Cell metabolism: equilibrium = reactant is converted to product at the same rate that the product is converted to the reactant, energy is equal on both sides of the equation, deltae = 0. If the e difference is large between the reactants and products conc difference at equilibrium will also be large. Increase in [reactants] = faster rxn rate of forward rxn: does not affect rxn rate of reverse rxn. Increase substrate = increase rate up to a certain point: enzymes with high affinity will increase rate quicker with more substrate. Inhibited by atp molecules which are made in step. Cell metabolism: stages of glucose oxidation, glycolysis = splitting of sugar, yields lots of coenzymes which help with krebs, cytosol, glucose + 2nad+ + 2adp + 2pi. 2 pyruvate + 2nadh + 2h+ +
