This has been the visit to this site since Sept. 12, 1996.

OUTLINE

DOUBLE HELIX

METABOLISM

CATABOLISM
ANABOLISM

ENERGY

KINETIC ENERGY
POTENTIAL ENERGY

ENERGY TRANSFORMATIONS

THERMODYNAMICS
FREE ENERGY
G = H - TS
EXERGONIC REACTIONS
ENDERGONIC REACTIONS

DOUBLE HELIX Fig. 5.28

A always pairs with T (in DNA) or U (in RNA)

G always pairs with C

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DNA and proteins as measures of evolutionary change

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CHAPTER 6

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METABOLISM = Totality of an organism's chemical processes

a series of enzymatically controlled reactions

Fig. 6.1

2 major types of reactions:

2) ANABOLIC = Pathways that consume energy to build macromolecules (e.g. condensation reactions)

Energy from Catabolic used to drive Anabolic reactions.

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ENERGY:

ENERGY = The capacity to do work

KINETIC ENERGY = Energy in the process of doing work

e.g. Heat = Thermal energy = Kinetic energy expressed in movement of molecules

or e.g. Light Energy = light energy from the sun that powers photosynthesis

POTENTIAL ENERGY = Energy of position or location

e.g. Water behind a dam (held against earth's gravity)

e.g. The energy stored in chemical bonds

ENERGY TRANSFORMATIONS

Energy can be transformed from one form to another

e.g. Potential energy in Gasoline can be transformed into kinetic energy of pistons.

or

e.g. Kinetic energy of sunlight can be transformed into potential energy of chemical bonds via photosynthesis

(Fig. 6.2 - sliding down a slide)

2 LAWS OF THERMODYNAMICS:

THERMODYNAMICS = Study of energy transformations

1st Law of Thermodynamics = Energy can transferred and transformed but it cannot be created or destroyed.

2nd Law of Thermodynamics = Every energy transfer or transformation makes the Universe more disordered (= increases entropy)

Combining 1st and 2nd laws = "The quantity of energy in the universe is constant but its quality is not"

Do Living organisms violate the second law?

Fig. 6.3

FREE ENERGY = Energy available to do work

G = H - TS

G = Gibb's free energy (energy available to do work)

H = total energy (or enthalpy)

T = Temperature in oK (degrees Kelvin = oC + 273)

S = entropy (= a measure of DISORDER)

Fig. 6.6

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CHEMICAL ENERGY AND LIFE:

EXERGONIC REACTIONS = Net loss of G (- delta G)

Products have less energy than reactants

ENDERGONIC REACTIONS = Net gain of G (+ delta G)

Products have more energy than reactants

Cellular Respiration as an example:

C6H12O6 + 6 O2 -----> 6 CO2 + 6H2O

Delta G = -686 kcal/mol

Energy must be conserved so the products store 686 kcal less than the reactants.

So is this exergonic or endergonic?