CHEMISTRY -Part Deux

Reactions, Energy and Water

ReactionsReactions:Form: Synthesis, Anabolic A+B

=> ABBreak: Decomposition, Catabolic AB

=> A + BExchange: Synthesis +

Decomposition AB + CD => AC + BD

Dissociation: Breaking IONIC bonds to form independent ions

Chemical Reactions: TermsReactants: Atoms and

Molecules present before the reaction

Products: Atoms or Molecules present after reaction

Chemical EnergyEnergy is neither created nor

destroyedEnergy changes form: Heat,

Kinetic (mechanical), Potential Chemical (potential)

Chemical Energy is stored in bondsReleasing that energy = FREE

Energy

Chemical Reactions do two things:

1. Produce new products

2. Transform Energy

Chemistry and EnergyBonds: Stored

EnergySynthesis

requires FREE energy

Decomposition releases FREE energy

Free = Available!

Take “2” to Review Take “2” to Review Energy: Energy: Be able to describe the four basic

forms of energyWhat kind of energy is STORED in

chemical bonds? (2 kinds)What kind of Energy is “available”What kind of reaction releases

FREE Energy?

Energy “Homeostasis”Energy “Homeostasis”Familiar Phrases:

I’m all out of energy… “What a bundle of energy!” “Energy in = Energy out”

ENERGY CURRENCY OF LIFE “Free Energy” makes things happenATP is a special molecule – delivering

“Free Energy” to get the job doneATP cannot be stockpiled….

ATP Turnover…ATP Turnover…Synthesis: Restoring the free

energy of ATP by adding P:ADP + P ATP

Decomposition: Releasing free energy for work by losing P:ATP ADP + P

Energy Homeostasis is the balance of ATP Supply and Demand

FACT:When Chemical Bonds are broken,

MOST OF THE ENERGY IS RELEASED AS HEAT!

In Human metabolism ~ 80% is released as heat

That leaves ~ 20% available for work or synthesis of other molecules = FREE ENERGY

Energy MoleculeATP: Adenosine TriPhosphateGlucose can be “decomposed”

to release its “bond” energy~20% of the FREE energy is

trapped and stored in 36-38 ATP when ONE GLUCOSE MOLECULE IS totally oxidized

QUESTION? Why does body temperature

Increase during

Exercise?

Reaction RatesReaction Rates Nature of Reactants:

Opposites attractWe share common interests (electrons)

Concentration of Reactants and ProductsAt parties, there are more people, more

chances of meeting someone with the “right chemistry”

“Uh-oh, my girlfriend is here too…”

Reaction RatesReaction Rates

Nature of ReactantsConcentration of Reactants and

ProductsTemperatureEnzymes

Reaction RatesReaction Rates

Nature of ReactantsConcentration of Reactants and

ProductsTemperatureEnzymes

Enzymes: “Matchmakers” in ChemistryProteins:

Unique shapes

Unchanged in reaction

“catalysts”

Take “2” to Review:Take “2” to Review:

Review Reaction Rates: Why don’t we vary body

temperature to speed up or slow down reaction rates?

What affect would “warming up” have on the ability to increase ATP synthesis for exercise demands?

Water: The “stuff” of Water: The “stuff” of life!life!Absorbs lots of heat without

changing temperatureLubricantReactant in many biological

reactions: CO2 + H2O => H2CO3

...and Water also:

Is a “solvent” for polar molecules and ions

Because of its polar nature, and the ability to dissolve ions, is a good medium to “conduct” currents!

Water and pH

Neutral = 7.0Body Fluids:

Saliva = 6.5 Blood = 7.4 Stomach = 1.0!

Acids, Bases and BuffersAcid: Substance which donates H+Base: Substance which donates

OH- which can accept H+Buffer: Substance which absorbs

either H+ or OH-: Acids and Bases can buffer one another

Salts: When Acids and Salts: When Acids and Bases Buffer Each OtherBases Buffer Each OtherA molecule made of the +ion

and -ion remaining when an acid and base buffer one another:

HCl => H+ + Cl-NaOH => OH- + Na+=> H2O + NaCl (Salt!)

BUFFERSBUFFERS

Resist Changes in pH Resist Changes in pH when acids or bases are when acids or bases are

added.added.

Assignment: Assignment: Read: Pages 25-37 Write about Energy Homeostasis:

Since ATP cannot be stockpiled what happens to ATP demand during exercise?

What happens to ATP supply during exercise?

During Exercise, will there be more ATP synthesis or more ATP decomposition reactions occurring?

CHALLENGE! (For extra-CHALLENGE! (For extra-credit)credit)Verify this statement:“Strong acids are strong

because they are substances which donate many H+ to a solution.”

True or False? Explain.First student to e-mail me the

explanation gets 5 points!