Energy Requirements of Living Organisms Learning Objectives To be able to explain Photosynthesis as a process in which light energy is used in the synthesis of organic molecules. Respiration as the process by which energy in organic molecules is made available for other processes within an organism. The synthesis of ATP from ADP and inorganic phosphate, and its role as the immediate source of energy for biological processes.

All living organisms require a continuous supply of energy to stay aliveAll living organisms require a continuous supply of energy to stay alive They obtain it either - 1) from the absorption of light energy OR 2) from chemical potential energy

Photosynthesis Transfers light energy to chemical potential energy. Is necessary for the survival of nearly all living organisms (with one or two exceptions). Supplies organisms with an energy supply and with a useable form of carbon: organic molecules.

Organic compounds Are those containing carbon as a major constituent, whether natural or artificial. Organisms which can use an inorganic carbon source (e.g. CO2) are termed autotrophs. Those which must be provided with ready-made organic carbon are termed heterotrophs.

Organic compounds Can be used in two ways: 1) As building blocks for the production of other organic molecules 2) As a source of chemical potential energy – released when the molecule is broken down during respiration.

Work Takes the form of – Anabolic reactions: synthesis of large molecules from smaller ones. (Opposites are catabolic reactions). Active transport Mechanical work e.g. muscle contraction, movement of cilia & flagella, amoeboid motion, movement of vesicles, etc. Occasionally, bioluminescence or electrical discharge.

ATP Structure of adenosine triphosphate:

Hydrolysis of ATP

Phosphorylation The production of ATP is called PHOSPHORYLATION It can take place in two main forms: –Photophosphorylation takes place in the membranes of the chloroplasts during photosynthesis –Oxidative Phosphorylation takes place in the membranes of the mitochondria during aerobic respiration

Read pages 2 – 4 in text book and make notes on energy in living organisms Answer question 1