chemical reactions and enzymes. energy and matter energy the ability to do work or cause change...
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Chemical Reactions and Enzymes
Energy and MatterEnergy and Matter Energy
The ability to do work or cause change
Occurs in various forms Can be converted to another form Forms important to biological
systems are chemical, thermal, electrical and mechanical energy
Free energy is the energy in a system that is available for work
States of MatterStates of Matter Atoms are in constant motion The rate at which atoms or molecules
in a substance move determines its state
Solid Molecules are tightly linked. Little energy
LiquidMolecules are not as
tightly linkedMedium amount of
energy
States of MatterStates of Matter
GasMolecules have little or no attraction to each otherFill the volume of the occupied containerMove most rapidly
To cause a substance to change state, thermal energy (heat) must be added to or removed from a substance
States of MatterStates of Matter
Energy and Chemical Reactions Living things
undergo thousands of chemical reactions as part of the life process
Many are very complex involving multistep sequences called biochemical pathways
Chemical equations represent chemical reactions Reactants are shown on
the left side of the equation
Products are shown on the right side A + B C + D
Energy and Chemical Reactions
Energy TransferEnergy Transfer Much of the energy
organisms need is provided by sugar (food) Undergoes a series
of chemical reactions in which energy is released (cell respiration)
The net release of free energy is called an exothermic reaction
Reactions that involve a net absorption of free energy are called endothermic reactions
Photosynthesis is an example
Energy TransferEnergy Transfer Mix Barium hydroxide and aluminum salt, and the products dissolve in water of hydration. This is VERY COLD!
Most chemical reactions require energy to begin
The amount of energy needed to start the reaction is called activation energy
Energy TransferEnergy Transfer
Certain chemical substances (catalysts) reduce the amount of activation energy required
Biological catalysts are called enzymes
CatalystsCatalysts
Enzymes are an important class of catalysts in living organisms Mostly protein Thousands of different kinds Each specific for a different
chemical reaction
CatalystsCatalysts
Enzyme Structure Enzymes work on
substances called substrates
Substrates must fit into a place on an enzyme called the active site
Enzymes are reusable!
Solutions
SolutionsSolutions A solution is a
mixture in which 2 or more substances are uniformly distributed in another substance
Solute is the substance dissolved in the solution Particles may
be ions, atoms, or molecules
Solvent is the substance in which the solute is dissolved
Water is the universal solvent
SolutionsSolutions
Acids and BasesAcids and Bases One of the most important aspects of a
living system is the degree of acidity or alkalinity
pH ScalepH Scale logarithmic scale
for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution
ranges from 0 to 14
Each pH is 10X stronger than next
e.g. ph 1 is 10 times stronger than ph 2
AcidsAcids Compounds that donate a proton (H+)
when dissolved in a solution. the lower the pH the stronger the acid 0-6 on the pH scale
HCl H+ + Cl-
BasesBases Compounds that accepts a proton (H+)
when dissolved in a solution. the higher the pH the stronger the base 8-14 on the pH scale
NaOH Na+ + OH-
pH 7.0 is neutral
Acids and BasesAcids and Bases
BuffersBuffers
Control of pH is very important
Most enzymes function only within a very narrow pH
Control is accomplished with buffers made by the body
Buffers keep a neutral pH (pH 7)
Buffers neutralize small amounts of either an acid or base added to a solution
Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels