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Biochem block3 Lecture 25 Chapter 4
What is the first law of thermodynamics?
The total amount of energy in the universe is constant. Energy can neither be created nor destroyed, but it can be transformed from one form into another.
What is the second law of thermodynamics?
The disorder of the universe always increases.
In other words, all chemical and physical processes occur spontaneously only when the disorder of the universe increases.
What is the third law of thermodynamics?
As the temperature of a perfect crystalline solid approaches absolute zero (0 K), disorder approaches zero.
What takes place in a thermodynamic "universe"?
Open system and Closed system
What is a open system?
Matter and energy
exchanged between system and surroundings (e.g., living organisms)
What is a closed system?
can be exchanged between system and surroundings.
What are state functions?
Depend only on initial and final state
Independent of the path taken to get there
What are 2 examples of state functions?
Enthalpy and Entropy
What are two examples of non state functions?
Work and Heat
What are carbohydrates made of?
Carbon, hydrogen, and oxygen
Changing glucose to gluconic acid is an example of what reaction?
The bond between two monosaccharides is called a:
Amylopectin is an example of what:
Which of these polysaccharides has a branched chain structure:
Amylose, amylopectin, glycogen, or cellulose
Glycogen and Amylopectin
How do oligosaccharide heteroglycans attach to proteins?
Either the side chain nitrogen of asparagine or the side chain oxygen of serine or threonine
What are typical GAG characteristics?
Linear polymers (that can make branches)
Carboxyl and/or sulfate groups
Amino group substitutions
What are some characteristics of proteoglycans?
Extremely high carbohydrate content (up to 95%)
Found on cell surface or extracellular matrix
What is true of glycoproteins?
1. Large GAG-containing structures
2. Proteins w/ carbohydrates attached
3. Found only outside cells.
Proteins with carbohydrates attached.
What is E?
What is q?
heat absorbed by a system
What is W?
Work done by the system
What is H?
What is PV?
Pressue-volume work done on or by the system
What is the equition for change in energy and which law?
ΔE = q + w
What is the equation for enthalpy and which law?
H = E + PV
What is close to zero in biological systems (1st law) and what does that mean to the relation of H and E?
ΔPV ≈ 0
ΔH = ΔE
What does a reaction do when ΔH < 0 and what term describes this?
The change in enthalpy is a negative value so the reaction will give off heat energy
1st Law of Thermodynamics
What does a reaction do when ΔH > 0 and what term describes this?
The change in enthalpy is postive and the reaction absorbs heat energy.
1st Law of Thermodynamics
What does a reaction do when ΔH=0 and what term describes this?
no heat energy exchange
Dead living organism
1st Law of Thermodynamics
What is spontaneous?
Physical or chemical changes that occur with the release of energy
ex. pysical change of ice melting.
What is Entropy (S) and which law does it apply?
Degree of system (anywhere in the system's universe) disorder
For bioprocesses, entropy increases take place in the surroundings
2nd Law of Thermodynamics
The more disorder, greater...
the S (Entropy) value
When is S positive?
Entropy is positive for a spontaneous process
What is the main equation for 2nd law of Thermodynamics?
ΔSuniv = ΔSsys + Δssurr
The change may occur in any part of the system
What is + ΔSuniv?
Means the process is spontaneous
What is −ΔSuniv?
Means the reverse process is spontaneous
What is nonspontaneous?
Processes that occur when a constant input of energy is required to support a change.
ex. ice will not form at temperatures above 0 degrees C
Why is the change in free energy useful?
Since ΔSuniv is too hard to know accurately, free energy change (ΔG) is a more useful measure
What is the equation of free energy change?
ΔG = ΔH - TΔS
What is free energy and how is it derived?
A thermodynamic function that can be used to predict the spontaneity of a process.
A state function that relates the first and second laws of thermodynamics
Represents the maximum useful work obtainable from a process.
If (-) ΔG, then the reaction is (3 things):
If (+) ΔG, then the reaction is (3 things):
If ΔG = 0, equilibrium, then the reaction is (3 things):
If the ΔG for a reaction is negative, then the reverse reaction ...
ΔG is positive
Explain the characteristics of the varibles in ΔG = ΔH - TΔS, if the reaction were favorable...
If TΔS is significantlly large or positive, then ΔG will be negative.
When ΔG is negative the reaction is spontaneous and exergonic which is favorable.
ΔSuniv (disorder in the universe) will increase
What is the difference between ΔG, ΔG°, and ΔG°’
: Uniform conditions for calculation
: Standard free energy change
: Biochemical standard state
What is ΔG° and its conditions?
Standard free energy change is denoted by ΔG°
: 25°C (298 K), 1.0 atm pressure, all solutes at 1.0 M
What is ΔG°' and its conditions?
free energy change at biochemical standard state conditions:
ΔG° at pH 7
For aA + bB ↔ cC + dD:
ΔG = ΔG° + RT ln (([C]c[D]d)/([A]a[B]b))
Why do the reactions discussed in bioenergetics still occur with a postive environment (endergonic/unfavorble) in the body?
Because of absorbed chemical energy from molecules such as ATP.
What is the primary cellular energy source?
Adenosine triphosphate (ATP)