ENERGY AND THE CELL

5.10 Energy Basics Energy is the capacity to do work and cause change –Work is accomplished when an object is moved against an opposing force, such as friction –There are two kinds of energy: –Kinetic energy: energy of motion –Potential energy: energy that an object possesses as a result of its location

5.10 Energy Basics Kinetic energy performs work by transferring motion to other matter –For example, water moving through a turbine generates electricity –Heat, or thermal energy, is kinetic energy associated with the random movement of atoms

5.10 Energy Basics An example of potential energy is water behind a dam –Chemical energy is potential energy because of its energy available for release in a chemical reaction

Potential energy being converted to kinetic energy.

Q: is the conversion of energy from one form to another 100% efficient?

Potential energy being converted to kinetic energy. A: No because heat is released into the universe during the conversion.

Fig. 8-2 Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform. Diving converts potential energy to kinetic energy. A diver has more potential energy on the platform than in the water.

5.10 Cells and Energy Cells are small units, a chemical factory, housing thousands of chemical reactions –The result of these chemical reactions is –maintenance of the cell, –manufacture of cellular parts, –and replication

5.11 Energy Laws Energy transformations within matter are studied by individuals in the field of thermodynamics –Biologists study thermodynamics because an organism exchanges both energy and matter with its surroundings

5.11 Energy Laws The first law of thermodynamics—energy in the universe is constant Basically, energy cannot be created or destroyed. Q: Does a light bulb “make” light? A: No. It converts electricity to light energy.

5.11 Energy Laws The second law of thermodynamics—energy conversions increase the disorder of the universe Entropy is the measure of disorder, or randomness The universe is becoming more and more disordered. Entropy is increasing.

Fig. 8-3 (a) First law of thermodynamics (b) Second law of thermodynamics Chemical energy Heat CO 2 H2OH2O +