Presentation on theme: "Energy and the Cell What do you know… About energy? Is it matter? What kinds are there? Can it be transformed to other forms?"— Presentation transcript:
Energy and the Cell
What do you know… About energy? Is it matter? What kinds are there? Can it be transformed to other forms?
What is energy? “Capacity to do work” Do living organisms need energy? YES!!!!!!!!!
Explain potential and kinetic energy of the roller coaster
Two Types of Energy Kinetic Actually doing work (moving) Potential Stored energy Due to location or arrange- ment (of atoms) 0-C-0
Examples Kinetic Pedaling a bike Heat = moves molecules electron jumps (go to Bohr’s quantum behavior of an atom) ICE STEAM
Potential Energy Potential Water behind a dam Electron’s position in an atom
Name the type:
What’s the most important type to living organisms? Chemical The energy in food molecules can be stored in the bonds
Explain the energy transfers:
When you break bonds… You release the energy that held the bonds together This energy can do work in the body.
Thermodynamics laws governing energy transfer
First Law of thermodynamics in closed system, energy can neither be created nor destroyed, only changed in form.
First Law of Thermodynamics Examples Light energy to chemical energy (from sun to sugar in a plant) Water behind a dam (potential) is released (kinetic)
How does this explain energy transfers?
What energy transfers are occurring?
Second Law of Thermodynamics energy transformations inevitably involve increased disorder or entropy. NOTE: it is the environment that is increasing disorder, not the cell
Entropy…what is that? Living things use this energy to create order (reduce entropy) locally, but the overall entropy of the solar system invariably increases.
In other words… If a particular system becomes more ordered, its surrounding become more disordered A cell makes organelles to increase order, but its surroundings become less orderly
Second Law energy of all kinds in our material world disperses or dissipates if it is not hindered from doing so
Must be spontaneous All spontaneous happenings in the material world are examples of the second law because they involve energy dispersing.
Could you explain that in other words? heat flows from hot (more energy) to cold (less energy) diffusion leads to substances becoming uniformly dispersed
You could think of cells as “Islands of Low Entropy”
Is the transformation perfect ? A cell cannot transfer or transform energy with 100% efficiency. Where does the lost energy go? Mostly lost as heat.
NOT Just organizing your desk
Do Worksheet Hot pans of water Water on Niagara Air in tires that got a puncture Speeding car hits a brick wall Spark in contact with gasoline Sun’s energy hits the ocean Huge earthquake under the ocean
Exergonic Reaction Releases Energy Begins with reactants whose covalent bonds contain more energy than its products
Exergonic: Releasing Energy Burning One big step Breaking bonds Many smaller steps
Exergonic Example Glucose (reactant) breaks down into carbon dioxide and water (products) C 6 H 12 O 6 CO 2 + H 2 O
“Cellular Respiration” Breaking glucose molecules to release energy and store it in a form the cell can use (ATP molecules) “slow burn”
Endergonic Reaction The products have more energy than the reactants Requires an input of energy Usually in the form of ATP
Endergonic Reaction Carbon dioxide and water combine to form glucose CO 2 + H 2 O C 6 H 12 O 6
“Cellular Metabolism” Sum of exergonic and endergonic reactions of cells CO 2 + H 2 O C 6 H 12 O 6 Less energymore energy molecules molecules
ATP No…not the new rock band from Japan Well, what is it?
ATP Adenosine Triphosphate “cell’s batteries” “energy currency”
How are they different? Adenosine triphosphate Adenosine diphosphate
Third Phosphate Acts as an energy shuttle
Making ADP + Pi ATP is energy rich and breaks down into ADP and Pi (inorganic phosphate) + energy is exergonic
Making ATP energy + ADP + Pi -> ATP is endergonic requiring the input of energy.
Which has more energy? ATP or ADP? Answer: ATP
Phosphorylation Adding of a phosphate group to a molecule
Energy Coupling Energy released from exergonic reactions drive endergonic reactions ADP + Pi ATP +
REACTIONS The end products of a reaction may have more (endergonic) or less (exergonic) energy than the substrate molecules.
REACTIONS Most reactions are reversible, occur in both directions - reactants -> end products AND end products -> reactants.
REACTIONS Reversible reactions move toward an equilibrium, a state in which the reaction occurs at about the same rate in both directions.
So... ATP is like money in a checking account
PPP Adenosine triphosphate (ATP) PP P + Adenosine diphosphate (ADP) Hydrolysis of ATP ATP + H2O ADP + P (exergonic) Hydrolysis (add water)
PPP Adenosine triphosphate (ATP) PP P + Adenosine diphosphate (ADP) Dehydration of ATP ADP + P ATP + H2O (endergonic) Dehydration synthesis (remove water) (remove water)
ATP Breaks down readily Would break down spontaneously except for the energy barrier
If entropy is spontaneous… Why aren’t we all just spontaneously combusting?
Energy of Activation E A The amount of energy that reactants must absorb to start a chemical reaction
But what if… The barrier is too great and the reaction cannot go… Use ENZYMES
Enzymes “Biological Catalysts” (speed up a reaction without being changed themselves)
Enzymes Usually end in –ase Usually named for what they work on EXAMPLE: Lipase works on Lipids
How do enzymes work? Each enzyme has a specific shape, which will determine which reactants it will work on
Active Site- small area where enzyme and substrate work Substrate=A substance that the enzyme acts on
Induced Fit Slight change in the shape of the active site of an enzyme as it embraces its substrate (like grasping hands) Enzyme animation
Is an enzyme… Able to be used over and over? YES!!!!!!!!!
Most enzymes… Work best at what temperature? o C What happens at high temperatures? Denatures them (unravels) Why is salty bad? Salt ions interfere with chemical bonds
Most enzymes… What is the optimal pH? 6-8 What does too low (too acidic) of pH do to enzymes? Extra H+ ions interfere with chemical bonds
Cofactores Nonprotein helpers EXAMPLES: Zn, Fe, Cu (inorganic ones) Vitamins like B 6 (organic ones)=also called coenzymes
Enzyme Inhibition Competetive inhibitor Resembles the enzyme and competes for the active site Noncompetetive inhibitor Does not enter the activ site Binds somewhere outside the active site Inhibitor animations
Negative Feedback When a cell’s supply exceeds the demand Negative Feedback animationNegative Feedback animation