Unit 3 – Metabolism of Life Big Idea 2: Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis.

In order for life to occur, it requires a highly ordered system In order for life to occur, it requires a highly ordered system. This system depends heavily on the availability of free energy. Free energy, also referred to as Gibbs Free Energy, is basically a sum total amount of energy found in a system. Within the context of biological systems, Free Energy can work in two different ways in a single, simple reaction. These reactions cause order These reactions cause entropy Exergonic – The release of energy, such as in a campfire. Endergonic – Require the input of energy, such as in Photosynthesis These reactions can occur spontaneously, since they do not require input of energy. These reactions cannot occur spontaneously, since they require a constant input of energy.

In order for life to occur, it requires a highly ordered system In order for life to occur, it requires a highly ordered system. This system depends heavily on the availability of free energy. In an exergonic reaction, energy is released, most often as heat, resulting in the products being of a lower energy state than the reactants. In an endergonic reaction, energy must be supplied from something (often the sun), resulting in a higher energy state of the products, as compared with the reactants.

AB A + B A + B AB Two major types of metabolic reactions – Catabolism Review: When these reactions occur in living systems, they fall into two categories. Two major types of metabolic reactions – Catabolism Anabolism - the breaking down of complex organic compounds, resulting in simpler compounds -the building up of organic compounds from simpler compounds, resulting in more complex compounds AB A + B A + B AB The reaction that performs anabolic action in the human body is called Condensation The reaction that performs catabolic action in the human body is called Hydrolysis. Since life requires order to be sustained, living systems couple processes that increase entropy (disorder) with those that decrease entropy (create order)

Which of these reactions are Exergonic Which of these reactions are Exergonic? Which of these reactions are Endergonic?

Review: Enzymes are the parts of biological systems that “do things,” but chemical reactions can occur in very similar ways without them.

Energy input must exceed energy lost to entropy to maintain order and power cellular processes. Cells use energy in the form of ATP, since the creation of ATP is energetically favorable. http://www.biologyinmotion.com/atp/index.html

Energy input must exceed energy lost to entropy to maintain order and power cellular processes. Cells use energy in the form of ATP, since the creation of ATP is energetically favorable.