Energy and the cell Ms. Rosendo Science 10th B

Objective Define energy and the types of energy. Describe the energy flow in an ecosystem. Determine why cells need energy.

Importance of energy Biological processes involve a certain amount of work, therefore every organism needs energy to do this work. Cells use energy in processes such as growth, reproduction and up-keeping. The sun is the principal source of energy that sustains life.

Bioenergetics Area of biology that studies the energetic processes in living organisms. Cells can obtain energy many ways, but in very few times that energy can be applied directly to activate cellular processes. Therefore, the cell uses metabolic mechanisms to convert energy from one way to the other. The energy in a cell can be altered via mechanical, chemical and electrical form.

Important concepts about energy Kinetic energy – energy related to movement. Potential energy – energy that is stored and available to do work. 1st Law of Thermodynamics – energy cannot be created nor destroyed, it can only be transformed. 2nd Law of Thermodynamics – no transfer is 100% efficient, there is always a loss of energy in the form of heat to the environment. Entropy – measure used to indicate the degree of mess in a system. Organized energy, that is usable, has a low entropy. Enthalpy – total amount of energy in matter.

Metabolism Metabolism is the series of chemical reactions that allow the organism to full fill his activities. Anabolism – synthesis of molecules, via that consumes energy. Catabolism – degradation of molecules, via that produces energy. These process occur at the same time and together. Therefore, the energy that is released in catabolism is used to produce more molecules in anabolism.

ATP Molecule

Metabolic Reactions

Redox Reactions (Oxidation and reduction) Transfer of electrons. Oxidation – process where the substance looses electrons. Reduction – process where the substance gains electrons. The substance that looses electrons gives away its energy. This occurs in: Photosynthesis Cellular Respiration ATP Synthesis

Important REDOX Molecules NAD+ = NADH NADP+ = NADPH FAD+ = FADH

Enzymatic Activities Enzymes are reaction catalysts. Most of them are proteins. They modify and accelerate the reaction time in chemical reactions. Enzymes are not consumed in the reaction, they regenerate one it is done. They can control the reaction process. They work by specificity, forming an enzyme substrate complex.

Enzymatic Activity Process Enzyme Substrate ES Complex ES Complex Enzyme Product (s)