The Flow Of Energy: Bio 30 Nwrc

The Flow of Energy Bio 30 NWRC

Cellular Metabolism Metabolic processes – all chemical reactions that occur in the body Two types of metabolic reactions Anabolism • larger molecules are made from smaller ones • requires energy •(endergonic)

Catabolism • larger molecules are broken down into smaller ones • releases energy •-(exergonic)

Energy for Metabolic Reactions Energy • ability to do work or change something • heat, light, sound, electricity, mechanical energy, chemical energy • changed from one form to another • involved in all metabolic reactions Release of chemical energy • most metabolic processes depend on chemical energy • breakdown of glucose generates chemical energy to promote cellular metabolism • cellular respiration releases chemical energy from molecules and makes it available for cellular use

Anabolism Anabolism provides the materials needed for cellular growth and repair – free energy is needed Dehydration synthesis • type of anabolic process • used to make polysaccharides, triglycerides, and proteins • produces water

Anabolism-Endergonic reactions

Catabolism- exergonic reaction Catabolism breaks down larger molecules into smaller ones Releases free energy • a catabolic process • used to decompose carbohydrates, lipids, and proteins • water is used to split the substances

Catabolism

Sources of free Energy • Adenosine triphosphate (ATP) is the unit of energy used in all living cells. This molecule is produced and broken down in metabolic processes in all living systems. • ATP can store and transport the energy we need to do just about everything that we do. Essentially all metabolic functions of living cells require energy for operation and obtain it directly from stored ATP.

Why Are the Phosphate Groups Important? • These molecules can transport energy because phosphate bonds contain a lot of potential energy, which is released when they are broken. • Energy is stored in the covalent bonds between phosphates, with the greatest amount of energy between the second and third phosphate groups

Note that although this is a good picture there is no such word as “alot”

Another View

How Is ATP Actually Made? • ATP is produced by autotrophs during photosynthesis, as described, and is also produced by both autotrophs and heterotrophs during a catabolic process known as cellular respiration.

Where is ATP Made? • In eukaryotic cells, complex cells that possess a nucleus, ATP is synthesized in the tiny energy factories called mitochondria. In prokaryotes ATP synthesis occurs in the cytoplasm and plasma membrane.

ATP- The Unit of Cellular energy • Adenosine Triphosphate • each ATP molecule has three parts: – an adenine molecule – a ribose molecule – three phosphate molecules in a chain

ATP

• How it works • ATP works by losing the endmost phosphate group when instructed to do so by an enzyme. This reaction releases a lot of energy, which the organism can then use to build proteins, contact muscles, etc. The reaction product is adenosine diphosphate

ADP

When the organism is resting and energy is not immediately needed, the reverse reaction takes place and the phosphate group is reattached to the molecule using energy obtained from food or sunlight. Thus the ATP molecule acts as a chemical 'battery', storing energy when it is not needed, but able to release it instantly when the organism requires it.

• When carbohydrates and other foods are consumed by the body, they also contain energy. When they are broken down, the energy is released and, in many cases, the energy is used to reattach the phosphate molecule to the ADP, turning it back into ATP. Then the cycle of bond-breaking and bond-making begins all over again, alternately releasing and storing energy, as needed. A convenient way to remember the cycle is ATP = ADP + P + Energy

End of Section 1