Chapter 3: Energy, Catalysis, Biosynthesis: Do Cells defy Physics?

Paradox of the Cell

• All closed systems tend to move towards disorder

• Cells are highly ordered

• These molecules did not arise from randomness

How can disordered systems become ordered

With energy input

What happens to overall universed when cells create ordered molecules

• Universe is still more disordered

• Molecules around cell become more disordered as cell becomes more ordered

What is free energy when potential energy is used

• below 0 (-G)

• Kinetic (sun) —> chemical (release from bond) = +G

Where does energy for life come from

• Almost all of it comes from the sun

• Some organisms get energy from hydrothermal vents

What can food and solar energy create

Chemical gradient that produces ATP

Where is chemical energy stored

In highly reduced molecules (used through oxidation)

Spontaneous reaction

• Energy released from bonds

• Glucose + 6 Oxygen —→ 6 CO2 + 6 water

• -G

Nonspontaneous reaction

• Energy released from bonds

• Glucose + 6 Oxygen ←-- 6 CO2 + 6 Water

• +G

What are 3 ways a cell can make a nonspontaneous reaction proceed

• Increase product

• Decrease Reactant

• Add energy

What do enzymes do

• Decrease activation energy for spontaneous reactions

• Control direction of a reaction

• Direct energetically favorable reactions to do specific work

What do activated carriers do

Provide chemical energy to build other molecules and do work

Adenosine Triphosphate (ATP), Controlled and uncontrolled oxidation

AT is an activated carrier (provides energy)

Controlled Oxidation (energy storage)

Uncontrolled oxidation (heat)

DNA and RNA polymerization is…

Spontaneous addition of nucleoside triphosphate (NTP)

Have -G

What do enzymes do to make non-spontaneous reactions spontaneous

Couple reactions

How does ATP hydrolysis enable unfavorable reactions

through high-energy intermediate

First step of glycolsis (energetically favorable) is through high energy intermediate

Allows enzymes to control breakdown of glucose

Where is Energy Stored?

• Chemical bonds (sugar, ATP, NADH)

• Chemical gradients (H+ gradient in mitochondria)