ground rules of metabolism chapter 5. growing old with molecular mayhem free radical a molecule that...
TRANSCRIPT
![Page 1: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/1.jpg)
Ground Rules of Metabolism
Chapter 5
![Page 2: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/2.jpg)
Growing Old with Molecular Mayhem
Free radical
A molecule that has unpaired electrons
Highly reactive, can disrupt structure of molecules
![Page 3: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/3.jpg)
Superoxide Dismutase
• Catalyzes the formation of hydrogen peroxide from oxygen free radicals and hydrogen ions
• Accumulation of hydrogen peroxide can be lethal to cells
![Page 4: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/4.jpg)
Catalase
Catalyzes the formation of oxygen and water from hydrogen peroxide
2H2O2 ----------> 2H2O + O2
![Page 5: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/5.jpg)
Roundworm Experiments
• Diet supplemented with superoxide dismutase and catalase increased life span of normal worms
• Diet also allowed worms genetically-engineered for susceptibility to free radicals to live normal life span
![Page 6: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/6.jpg)
What is Energy?
• Capacity to do work
• Forms of energy– Potential energy– Kinetic energy– Chemical energy
![Page 7: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/7.jpg)
What Can Cells Do with Energy?
• Energy inputs become coupled to
energy-requiring processes
• Cells use energy for:
– Chemical work
– Mechanical work
– Electrochemical work
![Page 8: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/8.jpg)
First Law of Thermodynamics
• The total amount of energy in the universe remains constant
• Energy can undergo conversions from one form to another, but it cannot be created or destroyed
![Page 9: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/9.jpg)
One-Way Flow of Energy
• The sun is life’s primary energy source
• Producers trap energy from the sun and convert it into chemical bond energy
• All organisms use the energy stored in the bonds of organic compounds to do work
![Page 10: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/10.jpg)
Second Law of Thermodynamics
• No energy conversion is ever 100
percent efficient
• The total amount of energy is flowing
from high-energy forms to forms
lower in energy
![Page 11: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/11.jpg)
Entropy
• Measure of degree of disorder in a system
• The world of life can resist the flow toward maximum entropy only because it is resupplied with energy from the sun
![Page 12: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/12.jpg)
Energy Changes & Cellular Work
Energy changes in cells tend to run spontaneously in the direction that results in a decrease in usable energy
![Page 13: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/13.jpg)
Endergonic Reactions
• Energy input
required
• Product has more
energy than starting
substances
product withmore energy
(plus by-products602 and 6H2O)
ENERGY IN
6 12
![Page 14: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/14.jpg)
Exergonic Reactions
• Energy is released
• Products have less energy than starting substance
ENERGY OUT
energy-richstarting
substance
+602
products with less energy
6 6
![Page 15: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/15.jpg)
The Role of ATP
• Cells “earn” ATP in exergonic reactions
• Cells “spend” ATP in endergonic reactions
P P P
ribose
adenine
![Page 16: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/16.jpg)
Electron Transfers
• Electrons are transferred in virtually
every reaction that harnesses energy
for use in the formation of ATP
• Coenzymes assist in electron transfers
![Page 17: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/17.jpg)
Electron Transport Systems
• Arrangement of enzymes, coenzymes,
at cell membrane
• As one molecule is oxidized, next is
reduced
• Function in aerobic respiration and
photosynthesis
![Page 18: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/18.jpg)
Concentration Gradient
• Means the number of molecules or ions in one region is different than the number in another region
• In the absence of other forces, a substance moves from a region where it is more concentrated to one one where it’s less concentrated - “down” gradient
![Page 19: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/19.jpg)
Diffusion
• The net movement of like molecules or ions down a concentration gradient
• Although molecules collide randomly, the net movement is away from the place with the most collisions (down gradient)
![Page 20: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/20.jpg)
Factors Affecting Diffusion Rate
• Steepness of concentration gradient– Steeper gradient, faster diffusion
• Molecular size– Smaller molecules, faster diffusion
• Temperature– Higher temperature, faster diffusion
• Electrical or pressure gradients
![Page 21: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/21.jpg)
Which Way Will a Reaction Run?
• Nearly all chemical reactions are
reversible
• Direction reaction runs depends upon
– Energy content of participants
– Reactant-to-product ratio
![Page 22: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/22.jpg)
Chemical Equilibrium
HIGHLYSPONTANEOUS
EQUILIBRIUM
HIGHLYSPONTANEOUS
RELATIVE CONCENTRATION
OF PRODUCT
RELATIVE CONCENTRATION
OF REACTANT
![Page 23: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/23.jpg)
Chemical Equilibrium
• At equilibrium, the energy in the reactants equals that in the products
• Product and reactant molecules usually differ in energy content
• Therefore, at equilibrium, the amount of reactant almost never equals the amount of product
![Page 24: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/24.jpg)
Energy Relationships
ATP
BIOSYNTHETIC PATHWAYS(ANABOLIC)
ENERGY INPUT
DEGRADATIVE PATHWAYS(CATABOLIC)
energy-poor products(such as carbon dioxide, water)
large energy-rich molecules(fats, complex carbohydrates,
proteins, nucleic acids)
simple organic compounds(simple sugars, amino acids,
fatty acids, nucleotides)
ADP + Pi
![Page 25: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/25.jpg)
Participants in Metabolic Pathways
• Energy Carriers
• Enzymes
• Cofactors
• Substrates
• Intermediates
• End products
![Page 26: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/26.jpg)
Types of Reaction Sequences
BRANCHING PATHWAY:
LINEAR PATHWAY: CYCLIC PATHWAY:
A B C D EF
K J I G
N M L H
![Page 27: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/27.jpg)
Enzyme Structure and Function
Enzymes are catalytic molecules
They speed the rate at which reactions approach equilibrium
![Page 28: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/28.jpg)
Four Features of Enzymes
1) Enzymes do not make anything happen that could not happen on its own. They just make it happen much faster
2) Reactions do not alter or use up enzyme molecules
![Page 29: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/29.jpg)
Four Features of Enzymes
3) The same enzyme usually works for both the forward and reverse reactions
4) Each type of enzyme recognizes and binds to only certain substrates
![Page 30: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/30.jpg)
Activation Energy
• For a reaction to occur, an energy barrier must be surmounted
• Enzymes make the energy barrier smaller
activation energywithout enzyme
activation energywith enzyme
energyreleased
by thereaction
products
starting substance
![Page 31: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/31.jpg)
Induced-Fit Model
two substrate
molecules
active sight
substratescontactingactive siteof enzyme
TRANSITIONSTATE(tightestbinding butleast stable)
endproduct
enzymeunchangedby thereaction
• Substrate molecules are brought together
• Substrates are oriented in ways that favor reaction
• Active sites may promote acid-base reactions
• Active sites may shut out water
![Page 32: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/32.jpg)
Factors Influencing Enzyme Activity
Temperature
pH
Salt concentration
Allosteric regulators
Coenzymes and cofactors
![Page 33: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/33.jpg)
Allosteric Activation
allosteric activator
vacantallosteric binding site
active site altered, can bind substrate
active site cannot bind substrate
enzyme active site
![Page 34: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/34.jpg)
Allosteric Inhibition
allosteric inhibitor
allosteric binding site vacant; active site can bind substrate
active site altered, can’t bind substrate
![Page 35: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/35.jpg)
Feedback Inhibition
enzyme 2 enzyme 3 enzyme 4 enzyme 5
enzyme 1
SUBSTRATE
END PRODUCT
(tryptophan)
A cellular change, caused by a specific activity, shuts down the activity that brought it about
![Page 36: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/36.jpg)
Effect of Temperature
• Small increase in temperature increases molecular collisions, reaction rates
• High temperatures disrupt bonds and destroy the shape of active site
![Page 37: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/37.jpg)
Effect of pH
![Page 38: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/38.jpg)
Enzyme Helpers
• Cofactors– Coenzymes
• NAD+, NADP+, FAD• Accept electrons and hydrogen ions; transfer
them within cell• Derived from vitamins
– Metal ions• Ferrous iron in cytochromes
![Page 39: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/39.jpg)
Cell Membranes Show Selective Permeability
O2, CO2, and other smallnonpolar molecules;and H2O
C6H12O6, and other large, polar(water-soluble) molecules; ions such as H+, Na+, CI-, Ca++; plus H2O hydrogen-bonded to them
X
![Page 40: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/40.jpg)
Membrane Crossing Mechanisms
Diffusion across lipid bilayer
Passive transport
Active transport
Endocytosis
Exocytosis
![Page 41: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/41.jpg)
• Span the lipid bilayer
• Interior is able to open to both sides
• Change shape when they interact with solute
• Play roles in active and passive transport
Transport Proteins
![Page 42: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/42.jpg)
Passive Transport
• Flow of solutes through the interior of passive transport proteins down their concentration gradients
• Passive transport proteins allow solutes to move both ways
• Does not require any energy input
![Page 43: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/43.jpg)
Passive Transportsolute
![Page 44: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/44.jpg)
Active Transport
• Net diffusion of solute is against concentration gradient
• Transport protein must be activated
• ATP gives up phosphate to activate protein
• Binding of ATP changes protein shape and affinity for solute
![Page 45: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/45.jpg)
Active Transport
• ATP gives up phosphate to activate protein
• Binding of ATP changes protein shape and affinity for solute
P
P
P
P
High solute concentration
Low solute concentration
ATP ADP
![Page 46: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/46.jpg)
Bulk Transport
Exocytosis
Endocytosis
![Page 47: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/47.jpg)
Osmosis
• Diffusion of water molecules across a selectively permeable membrane
• Direction of net flow is determined by water concentration gradient
• Side with the most solute molecules has the lowest water concentration
![Page 48: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/48.jpg)
Tonicity
Refers to relative solute concentration of two fluids
Hypertonic - having more solutes
Isotonic - having same amount
Hypotonic - having fewer solutes
![Page 49: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/49.jpg)
Tonicity and Osmosis
2% sucrose
water 10% sucrose 2% sucrose
![Page 50: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/50.jpg)
Increase in Fluid Volume
compartment1
HYPOTONIC SOLUTION
membrane permeable towater but not to solutes
HYPERTONICSOLUTION
compartment2
fluid volume increasesIn compartment 2
![Page 51: Ground Rules of Metabolism Chapter 5. Growing Old with Molecular Mayhem Free radical A molecule that has unpaired electrons Highly reactive, can disrupt](https://reader035.vdocument.in/reader035/viewer/2022062718/56649ebe5503460f94bc8263/html5/thumbnails/51.jpg)
Pressure and Osmosis
• Hydrostatic pressure– Pressure exerted by fluid on the walls that
contain it– The greater the solute concentration of the
fluid, the greater the hydrostatic pressure
• Osmotic pressure– Amount of pressure necessary to prevent
further increase of a solution’s volume