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Biochemistry – Basic Concepts

Biochemistry – basic concepts

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Page 1: Biochemistry – basic concepts

Biochemistry – Basic Concepts

Page 2: Biochemistry – basic concepts

Reaction, reactants and products

A + B →CWhat is a reactant?What is a product?IntermediatesReversible / irreversibleRate of reaction Rate constant

Page 3: Biochemistry – basic concepts

Energy related with reactions

Free energy diagramsExothermic and endothermic reactions

Page 4: Biochemistry – basic concepts

Laws of thermodynamics

Thermodynamics is the study of the effects of work, heat, and energy on a system

All of thermodynamics can be expressed in terms of four quantities Temperature (T) Internal Energy (G) Entropy (S) Heat / Enthalpy (H)

Page 5: Biochemistry – basic concepts

First law

Energy can be changed from one form to another, but it cannot be created or destroyed.

The total amount of energy and matter in the Universe remains constant, merely changing from one form to another.

The First Law of Thermodynamics (Conservation) states that energy is always conserved, it cannot be created or destroyed. In essence, energy can be converted from one form into another

ΔU = Q - W

Page 6: Biochemistry – basic concepts

Process terminology

Adiabatic – no heat transferredIsothermal – constant temperatureIsobaric – constant pressureIsochoric – constant volume

Page 7: Biochemistry – basic concepts

An adiabatic process transfers no heat therefore Q = 0

ΔU = Q – WWhen a system expands adiabatically, W is

positive (the system does work) so ΔU is negative.

When a system compresses adiabatically, W is negative (work is done on the system) so ΔU is positive

Page 8: Biochemistry – basic concepts

An isothermal process is a constant temperature process. Any heat flow into or out of the system must be slow enough to maintain thermal equilibrium

For ideal gases, if ΔT is zero, ΔU = 0Therefore, Q = W

Any energy entering the system (Q) must leave as work (W)

Page 9: Biochemistry – basic concepts

An isobaric process is a constant pressure process. ΔU, W, and Q are generally non-zero, but calculating the work done by an ideal gas is straightforward

W = P·ΔVWater boiling in a saucepan is an example of

an isobar process.

Page 10: Biochemistry – basic concepts

An isochoric process is a constant volume process. When the volume of a system doesn’t change, it will do no work on its surroundings. W = 0

ΔU = QHeating gas in a closed container is an

isochoric process

Page 11: Biochemistry – basic concepts

2nd law

"in all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state."

This is also commonly referred to as entropy.

ΔG = ΔH – T ΔSG – Free energy / potential energy of the stateH – Enthalpy S – entropy / Disorder/ messiness