Cellular Respiration and Photosynthesis (I. Energy (Law of Conservation…
Energy is a property or characteristic of things that can make something happen
Law of Conservation of Energy
Energy can neither created nor destroyed ( First Law of Thermodynamics
Energy can be transformed from one form to another
Every energy transformation is inefficient( Second Law of Thermodynamics)
Types of Energy:
II. ATP and Cellular Respiration
Two Step Process to Provide Energy Needed
, ATP is synthesized from ADP plus a phosphate using chemical energy released when organic molecules like glucose undergo a process called cellular respiration.
, the hydrolysis of ATP provides the energy for many biological processes (e.g. synthesizing molecules and pumping ions into and out of cells).
- is the major process that produces ATP, so chemical energy is available in the form that is used for many biological processes. The following pair of chemical equations gives a highly simplified overview of the cellular respiration of glucose.
Only about 30% the energy released by the cellular respiration of glucose is captured in the production of ATP; much of the energy is lost as thermal energy.
Cellular respiration can produce ATP using glucose, fatty acids, glycerol or amino acids as input molecules
Difference Among Food, Calories, and Energy
Energy is a property of all sorts of biological and non-biological systems (e.g. the chemical energy available from cellular respiration of food molecules or the kinetic energy of moving muscles or cars).
A calorie is a unit of measure of energy.
Food contains organic molecules which can be used for cellular respiration which produces ATP; hydrolysis of ATP provides the energy for the processes of life. Food also provides atoms and molecules that can be used for growth and repair of body tissues.
Photosynthesis converts light energy to chemical energy. Specifically, photosynthesis uses the sun's energy, carbon dioxide and water to produce sugar molecules and oxygen.
6 CO2 + 6 H2O ----------> C6 H12O6 + 6 O2
Process of Photosynthesis
The second stage of photosynthesis, known as the Calvin cycle, produces a 3-carbon molecule which is converted to glucose and fructose.
Glucose and fructose can be converted to sucrose which can move throughout the plant and provides input molecules for cellular respiration. Glucose can also be used to produce starch (a storage molecule), cellulose (a major structural molecule in plants) and carbon-containing molecules that are used in the synthesis of lipids and amino acids.
Photosynthesis begins with light reactions which convert the energy in sunlight to chemical energy.
Energy is some material substance that can take on various physical characteristics (e.g. light energy, chemical energy, kinetic energy, thermal energy).
Energy is released when bonds are broken (e.g. the breakdown of glucose or ATP releases energy).
Chemical energy is stored in high energy molecules such as glucose or ATP.
Energy is a property of various systems (e.g. thermal energy increases as the random motion of molecules or other microscopic particles increase).
A chemical bond results from an attraction between the bonded atoms, so it requires energy input to separate the atoms and break a chemical bond. Conversely, the formation of a chemical bond releases energy.
Because energy can only be released when molecules react to form other molecules, it is more accurate to think of energy as stored in a system (e.g. a system of reactants), rather than in individual molecules or bonds.