Intro to Cell Energetics I. Energy and Life A. All organisms require energy to carry out life processes B. Energy is defined as the ability to do work or cause change I. Energy and Life A. All organisms require energy to carry out life processes B. Energy is defined as the ability to do work or cause change

Intro to Cell Energetics C.Two types of energy: 1. Kinetic energy is action energy (e.g. speeding car) 2. Potential energy is stored energy that can do work (e.g. charged battery) a.Molecules that have a lot of potential energy are usually unstable ✓ Why is this a problem? C.Two types of energy: 1. Kinetic energy is action energy (e.g. speeding car) 2. Potential energy is stored energy that can do work (e.g. charged battery) a.Molecules that have a lot of potential energy are usually unstable ✓ Why is this a problem?

D.Sources of Energy 1. Almost all energy in organisms originally comes from the sun 2. Autotroph – organism that makes its own food a.Photoautotroph – organisms that use energy in sunlight to make food b.Chemoautotroph – organisms that use energy stored in inorganic compounds to make food c.Autotrophs are the producers of the biosphere Intro to Cell Energetics

3.Heterotroph – organism that cannot make its own food, so it must obtain energy by eating other organisms Is energy in cells stored as sunlight? Then how is the energy stored? Intro to Cell Energetics

E. ATP (Adenosine Triphosphate) 1.Molecule that stores energy for use in a cell 2.Has a lot of potential energy, but is very stable 3.Composed of adenine (base), ribose (5-carbon sugar), and three phosphate groups

DRAW ATP

F.Storing and Releasing Energy 1.Storing energy: add a phosphate to ADP a)ADP + phosphate + energy  ATP 2.Releasing energy: break chemical bond between 2 nd and 3 rd phosphate in ATP a)ATP  ADP + phosphate + energy Intro to Cell Energetics

3. Calorie is the amount of heat needed to raise the temperature of 1 gram of water 1° Celsius. Intro to Cell Energetics ATPADP + P i 7,000 cal ATP CYCLE (DRAW)

ADPATP Energy Adenosine triphosphate (ATP) Partially charged battery Fully charged battery Adenosine diphosphate (ADP) DRAW FIG 8-3, pg 203