Topic 5 Flashcards
Thermodynamics
is a special branch of chemistry that is concerned with the study of energy transformations that occur in a certain collection of matter
kinetic energy
is energy that can be associated with the relative motion of objects, movement, thermal, light, Sound or electrical.
potential energy
energy that is not kinetic but energy that matter possesses because of its location or chemical structure. Chemical energy is associated with potential energy being available in a chemical reaction
is stored energy that has the ability to do work (available energy). Chemical, Gravity, Elastic, Nuclear (energy in atoms nucleus)
STORED IN CHEMICAL BONDS
redox reactions
occur during certain chemical reactions, electron can be transferred from one atom to another
Reduction has a higher level of energy than oxidized form, and Reactions are always paired.
DURING A REDOX REACTION THE MOLECULE THAT GAINS AN ELECTRON HAS BEEN REDUCED AND NOW HAS A HIGHER ENERGY LEVEL
oxidation
involves losing electrons & increasing oxidation number
involves losing a hydrogen for a given compound
releases energy
reduction
involves gaining electrons and decreasing oxidation number
involves gaining a hydrogen for a given compound
stores energy
First Law of Thermodynamics
the energy of the universe is constant: and energy can be transferred and transformed, but it cannot be created or destroyed, only converted to other forms (Principle of Conservation of energy)
Second Law of Thermodynamics
Every energy transfer or transformation increase the entropy of the universe
All energy transformation are inefficient (Energy losses: Friction, Heat, Light, Sound, Eddy Currents)
Heat
thermal energy - associated with kinetic energy, as it involves random movement of atoms or molecules
Heat is an example of radiant or electromagnetic energy
Heat is the most convenient way of measuring energy: 1 calorie = heat required to raise 1 gram of water 1ºC
entropy
a measure of molecules disorder, or randomness
enthalpy
is the energy in a molecule’s chemical bonds (H)
free energy
the amount of energy available to break and form other chemical bonds in a particular defined system
(G)
endergonic
absorb energy from their surroundings
Energy is absorbed, (not Spontaneous)
Transforming kinetic to potential energy. (Ex: Photons of light converted to ATP in photosynthesis)
If ΔG is positive, the products have more free energy than the reactants, and requires an input of energy
exergonic
release energy to the surroundings
Energy is released, (Spontaneous)
Transforming Potential to Kinetic Energy. (Ex: Breakdown of Glucose via Glycolysis to produce ATP)
If ΔG is negative, the reactants have more free energy than the products, thus reaction will proceed spontaneously, and release excess free energy as heat
Exergonic reaction fuels an Endergonic reaction
activation energy
the energy required to initiate a chemical reaction
The Enzyme applies stress to distort particular bond to lower activation energy
catalysis
the increase in the rate of a chemical reaction by a catalyst
adenosine triphosphate (ATP)
the main energy currency for all cells and used for almost every energy-requiring process in the cell.
Composed of a …
Ribose – 5 carbon sugar
Adenine – purine nitrogen base
Chain of 3 phosphate bonded – Energy is stored in the bonds, as it takes an input of energy to create the bonds, the energy is then released when the bond is broken (ENERGY IN AN ATP MOLECULE IS STORED IN THE BONDS CONNECTING THE 2ND & 3RD PHOSPHATE GROUPS)
enzyme
globular proteins that act as biological catalysts (Some enzymes are RNA based)
Enzyme function can be affected by any chemical of physical conditions that can have an effect on the shape of the enzyme and thus affecting the rate of reactions
Rate of enzyme-catalyzed reaction depends on the concentrations of substrate and enzyme available.
can be either suspended in the cytoplasm or attached to cell membranes and organelles
Multienzyme complexes – subunits work together to form molecular machine, products can be delivered easily to next enzymes
Allosteric Enzymes – enzymes that can be either activate or become inactivated.
active site
are pockets or clefts for substrate binding, and the site where the enzyme-substrate complex forms
enzyme-substrate complex
forms a precise fit
effects of free energy on reactions
- If free energy decreases, the reaction can proceed. If free energy increases, the reaction can’t proceed.
- If Gibbs free energy is negative, the reaction is spontaneous. If Gibbs free energy is positive (exergonic), the reaction is not spontaneous (endergonic). If Gibbs free energy is zero, the reaction is in equilibrium.
- The rate of a chemical reaction depends on the free energy, entropy, and concentration of the reactants and products.
What is the importance of ATP in cellular processes?
- transports the energy necessary for all cellular metabolic activities
- serves as a shuttle, delivering energy to places within the cell where energy-consuming activities are taking place
How do enzymes work?
- Enzymes recognize and bind to their substrates through hydrogen bonds, ionic bonds, and hydrophobic interactions
- The formation of these temporary bonds creates tension on certain bonds, and can force a redistribution of electrons within the substrate molecules
- The strain imposed by physical forces/electron re-distribution, creates a strain on a covalent bond within the substrate molecule, resulting in bond breakage
- Substrate activation is the process of straining substrate bonds
A reaction will proceed spontaneously in which of the following conditions?
The reactants have a higher free energy than the products
What is the principal source of energy coming from in a biological world?
the sun’s release of protons
Enzymes require an optimal temp. & pH, otherwise what effect does changes in temp. & pH cause for enzymes?
the three-dimensional shape of the enzyme
