Chapter 6 Flashcards
Thermodynamics
Branch of chemistry concerned with energy changes
Energy and 2 states
Capacity to do work
1 Kinetic
2 Potential
Kinetic energy
Energy of motion (Breaking a bond)
Potential energy
Stored energy (form of a bond)
Calorie = calorie
Calorie is Kilocalorie
1 Kilocalorie = 1000 calories
Metabolism
Total of all chemical reactions carried out by an organism
Metabolism = anabolic + catabolic
Anabolic reactions
Use energy to build up molecules (Build monomers into polymers)
Catabolic reactions
Release energy by breaking down molecules. Breaking down polymers to make monomers. (starvation = breakdown of muscle)
Source of energy on earth
Energy flows into biological world from the sun
Photosynthesis
Capture energy (anabolism) and store as potential energy as sugars
First law of thermodynamics
Energy cannot be created or destroyed. Energy can only change from one form to another. Total amount of energy in universe remains constant
Second law of thermodynamics
Entropy (disorder) is continuously increasing. Energy transformations proceed spontaneously to convert matter from a more ordered/less stable form to a more unstable form
G=
H=
T=
S=
G= energy available to do work
H= Enthalpy, energy in a molecule’s chemical bond (Potential energy)
T= Absolute temperature
S= entropy, unavailable energy (disorder)
G = H - TS
Positive ΔG
Products have more free energy than reactants.
Endergonic and Anabolic
Requires input of energy
Monomers to polymers
ΔG =
Change in free energy
ΔH - TS
Negative ΔG
Products have less free energy than reactants (less bonds)
Exergonic and Catabolic
Release excess free energy, spontaneous (But could be slow)
Breaking things, breaking bonds
Activation Energy (Ea)
Extra energy required to destabilize an existing bond and initiate a chemical reaction
Increase Ea rate 2 ways
Increasing energy of reacting molecules (Heat)
Lowering activation energy
Catalyst
Substances that influence chemical bonds in a way that lowers activation energy
Makes reaction proceed faster
Not used up in process
Cannot violate laws of thermodynamics (Endergonic cannot be spontaneous)
Enzymes
Biological Catalysts. Work by lowering activation energy.
Mostly proteins. Some RNA called ribozymes
ATP Adenosine Triphosphate
Chief currency of the cell
Composed of: Ribose - 5 carbon sugar, Adenine, chain of 3 phosphate groups. Made and used immediately. Travels to where it is needed.
ATP, ADP, AMP
Chain of phosphates key to energy storage because bonds are unstable and weak.
Nucleic acid (nucleotide) sugar, nitrogenous base, and phosphate
ATP 3 phosphate
ADP 2 phosphate
AMP 1 phosphate
ATP Hydrolysis drives
Endergonic reactions.
Coupled reactions of ATP
Energy released by ATP is used immediately by cell for an energy requiring function (Endergonic).
Substrate
substance on which the enzyme acts.
Active Site
Pockets or clefts for substrates binding.
Enzyme and substrate bind forms
Enzyme-substrate complex (tertiary structure). Applies stress to distort particular bonds to lower activation energy. Induced fit/ perfect fit
E + S = ES = E + P
Coenzymes
When the cofactor is a nonprotein organic molecule. Modified nucleotides are also used. Ex vitamins
Cofactors
These can be metal ions that are often found in the active site participating directly in catalysis
Inhibitor
Substances that bind to enzyme and decreases its activity
Competitive inhibitor
Competes with substrate for active site
Noncompetitive inhibitor
Binds to enzyme at a site other than active site (Allosteric site). Causes shape change that makes enzyme unable to bind to substrate
Allosteric enzymes
Enzymes exist in active and inactive forms
Allosteric inhibitor
Binds to allosteric site and reduces enzyme activity
Allosteric activator
Binds to allosteric site and increases enzyme activity
Metabolic Pathway or Biochemical Pathway
Chemical reactions that create/store or produce other chemical products for daily function. Reaction occur in a sequence. Product of one reaction is substrate for the next reaction
Feedback Inhibition
Metabolic pathways compete for resources. Limits extent of competition. Reaction product or by-product binds to allosteric site of enzyme involved in initial stages.
Concentrated product = pathway shut off
