energy is the capacity to do work energy is measured in kcals or joules examples: kinetic,...
TRANSCRIPT
ENERGY!!
What is energy?
Energy is the capacity to do work Energy is measured in kcals or joules
Examples: Kinetic, Thermal, Potential, Chemical
The Laws of Thermodyamics
The first law of thermodynamics
Energy cannot be created or destroyed in a reaction; It can only be transformed
Ex: Photosynthesis: Conversion of ____________ energy to _____________ energy!
The first law of thermodynamics…Consequences on Organisms
Living systems need to continually acquire and transform energy in order to do work necessary to remain alive (“metabolism”)
Ex: grow, repair, move, reproduce!
What is free energy (G)?
The energy available in a system to do work (Ex: transport, synthesis, reproduction, growth)
The second law of thermodynamics
Every times energy is transformed, some of the energy becomes unusable and the entropy of the universe increases
Ex: Cell Respiration: __________ of the chemical energy is converted and used for cellular work; _________ generates heat!
The second law of thermodynamics…Consequences on living systems
In order to increase internal order, living systems must process more ordered forms of matter into less ordered forms
Ex: Digestion followed by Cell Respiration!!
What is entropy (S)?
Entropy is the amount of disorder or randomness in a system
Ex: Your messy room
For each of the following examples, is entropy increasing or decreasing?
a. Hydrolysis of Proteins into Amino Acids: b. Synthesis of Glycogen from Glucose: c. Photosynthesis: d. Digestion of a cheeseburger: e. Transcription of DNA into mRNA: f. Cellular Respiration: g: A plant using raw materials to build a
leaf in the spring: h: Leaves decomposing in winter
Living Systems are “Open Systems”
Matter and energy move into living systems from the environment. Living Systems transform matter and energy and return it to the environment!!
What happens when there is a decrease in energy processing? What happens to the
entropy of the system?
Insufficient free energy production leads to disease and death!
Entropy INCREASES What if this
happens at the producer level of an ecosystem??
How do living systems regulate energy processing?
Multi-Step Metabolism! Free Energy production occurs in
multiple-step pathways, mediated by enzyme catalysts
“slow burn” energy production Increases efficiency!
The Kreb’s Cycle
Chemical reactions either release free energy or require free energy
Exergonic reactions release free energy (from covalent bonds) and therefore are spontaneous reactions (following activation)
Ex: Cellular Respiration, catabolism, digestion of polymers, decomposition
Chemical reactions either release free energy or require free energy
Endergonic reactions require an input of energy and therefore are not spontaneous
These reactions form products that have high chemical energy (stored)
Ex: Photosynthesis, Anabolism, Synthesis of Polymers from monomers
Gibbs Free Energy Equation
Used to determine if a process can occur spontaneously or not
ΔG = ΔH – TΔS ΔG = change in free energy
(- = exergonic, + = endergonic) ΔH = change in enthalpy for the
reaction (- = exothermic, + = endothermic)
T = Kelvin temperature ΔS = change in entropy
(+ = entropy increases, - = entropy decreases)
Gibbs Free Energy Equation
ΔG = ΔH – TΔS If ΔG is negative, free energy is
released (reaction will occur spontaneously and is exergonic)
If ΔG is positive, free energy is consumed (reaction will not occur spontaneously and is endergonic)
If free energy is not available, the reaction does not occur.
Sample Problem: Determine which reaction will occur spontaneously at 298K
Rxn 1: A + B —> ABReaction 2: CD —> C + D
ΔH: +245 KJ/mol ΔH: -334 KJ/mol ΔS: -.02 KJ/K ΔS: +.12 KJ/mol
In Terms of ΔG…
An exergonic reaction…will release free energy, be negative and will occur spontaneously
An endergonic reaction…requires the continuous input of energy, be positive and will not occur spontaneously (without free energy available, no reaction occurs)
Complete the following chart
Is ΔG positive or negative
Exergonic or Endergonic?
Spontaneous?
Products have more or less energy than
reactants?
Time Time
Energy
Energy
Why are anabolic and catabolic often coupled in living organisms?
Catabolic reactions release energy that can be used to drive anabolic reactions
They work TOGETHER
What is the source of energy in cells used to drive endergonic reactions?
ATP!
Describe the structure of ATP
Nucleoside Adenine Base Ribose Sugar 3 phosphate Groups
Which form has more energy stored: ATP or ADP or AMP?
Why is ATP considered a “high energy” molecule? How does ATP store energy?
Captures and releases free energy Releases a large amount of energy when
hydrolyzed Can phosphorylate other molecules to
transfer energy (adding a phosphate group)
Energy is stored in the covalent bonds between phosphates
Figure 5.12A_s2
ADP: Adenosine Diphosphate
P P P Energy
H2OHydrolysis
Ribose
AdenineP P P
Phosphategroup
ATP: Adenosine Triphosphate
ATP Cycle
ΔG = -7.3kcal when ATP -> ADP + Pi
What is a coupled reaction?
Time
Energy