an introduction to metabolism chapter 6: special proteins called enzymes
TRANSCRIPT
An Introduction to MetabolismChapter 6: Special Proteins Called Enzymes
Enzymes are Proteins that Act as Biological Catalysts
S + E S + E ES ES P + E P + E
Metabolism is the totality of an organisms chemical reactionsReactions that
build up things = Anabolic Require input of energy
Reactions that breakdown things = Catabolism Energy is released
Energy is the capacity to do work…Kinetic energy: Energy of motionPotential Energy: Energy stored in
matter that has the capacity to do work.Chemical Potential Energy: A form of
potential energy that is stored within the bonds of a molecule.
Laws that Govern Energy TransformationsFirst Law of Thermodynamics: Energy
can be transferred or transformed, but cannot be created or destroyed
Second Law of Thermodynamics: Every energy transfer or transformation results in increasing disorder of the universe (increasing Entropy)
Only a Portion of the Total Energy of Living Organism is Available to do Useful Work.
ENERGY in a cell
Energy lost to universe as heat, light, etc.
Energy used for cells metabolism
FREE ENERGY (G)
I don’t understand? How do the terms entropy, stability, free energy and spontaneous relate to each other?
If you have a lot of free energy you are ordered (low entropy). You are unstable and you want to release that energy spontaneously.
If have low free energy, you are stable and the system is disordered (high entropy). To become ordered again you need energy Non- spontaneous.
Let’s try these examples…
We can relate these terms mathematically using the Gibbs Equation
G = H G = H – TS– TS
Total energy of the system, not all the energy is available to do work
Energy lost in disordering the Universe as heat
G = G = H – TH – TSS
Let’s examine this equation further…What are some ways that we can have a spontaneous process? G < 0G < 0
G = G = H – TH – TSS
G = H – TSG = H – TSINITIAL
G = H – TSG = H – TSFINAL
G < 0G < 0 Negative,Spontaneous
CHANGE
You could do both at the same time and really
have a low GG
You could lower H
You could raise TS
Endergonic vs. Exergonic reactions
Closed vs. an Open System
All energy from catabolism (breakdown) must be captured in the
form of ATP do do useful work.
The ATP Cycle is the energy currency of the cell… It’s like a battery
+
ATP ADPInorganicphosphate
Energy
Energy
How does ATP perform work?
The ATP Cycle Connects Catabolic Paths with Anabolic Paths