Lecture 5 (Sept 4)

Lecture 5 (Sept 4) - Biological S nce 110A: I ntroduction...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 5: Enzymatic function and catalyzed reactions The laws of thermodynamics Free energy change ( G) in chemical reactions ATP: The energy currency of cells Coupled reactions driven by ATP hydrolysis Reduction-oxidation (redox) reactions Enzyme catalysts reduce activation energy Enzyme kinetics (Michaelis-Menten equation) Biological Sciences 110A: Introduction to Biology Kendal Broadie Reading in Chapter 3 (85-104) Karp
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
All chemical systems (and cells) are bound by the laws of thermodynamics 1. Energy is conserved . Energy can be converted from one form to another, but cannot be created or destroyed. 2. The entropy (disorder) of the universe (or any closed system) always increases. Reactions go “downhill” from a higher to a lower energy state. Living cells are highly ordered, and seem to defy the second law… How? Cells are not closed systems . Cells create and maintain order by using energy (light or chemical energy) obtained from their environment, some of which is returned to their environment as heat.
Background image of page 2
( G) of a chemical reaction G = H – T S H = enthalpy (~energy) change, T = temperature, S = entropy (~disorder) change H and S for a reaction can be either negative or positive. Examples: C 6 H 12 O 6 (glucose) + 6 O 2 > 6 H 2 O + 6 CO 2 H is negative and S is positive. G o = -686 kcal/mole. 2 H 2 + O 2 > 2 H 2 O Negative S is overcome by very negative H. G o is VERY negative. G = G products – G reactants G is dependent upon reaction conditions and the concentrations of reactants and products. G o (“standard free energy change”) refers to the free energy change under standard conditions (25 o C, 1 atm, 1 M [reactants, products]), and is used for comparing the thermodynamic favorability of reactions. G =
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 22

Lecture 5 (Sept 4) - Biological S nce 110A: I ntroduction...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online