An Introduction to Metabolism Chapter 6: Special Proteins Called Enzymes.

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An Introduction to Metabolism Chapter 6: Special Proteins Called Enzymes

Enzymes are Proteins that Act as Biological Catalysts S + E ES P + E

Metabolism is the totality of an organisms chemical reactions Reactions 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 motion Potential 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 Transformations First 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 dont 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.

Lets try these examples…

We can relate these terms mathematically using the Gibbs Equation G = H – TS Total energy of the system, not all the energy is available to do work Energy lost in disordering the Universe as heat G = H – T S G = H – T S

G < 0 Lets examine this equation further…What are some ways that we can have a spontaneous process? G < 0 G = H – T S G = H – T S G = H – TS INITIAL G = H – TS FINAL G < 0 G < 0 Negative, Spontaneous CHANGE You could do both at the same time and really G have a low G You could lower HYou 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… Its like a battery + ATPADP Inorganic phosphate Energy

How does ATP perform work?

The ATP Cycle Connects Catabolic Paths with Anabolic Paths

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