Energy and Metabolism

The Energy of Life The living cell generates thousands of different reactions Metabolism Is simply all the organism’s chemical reactions All molecules (nutrient molecules included) have stored (potential) energy in the bonds between their atoms

Metabolic Pathways A metabolic pathway has many steps that begin with a specific molecule and end with a product, each catalyzed by a specific enzyme Reactions that join small molecules together to form larger, more complex molecules are called anabolic. Reactions that break large molecules down into smaller subunits are called catabolic. Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1 Reaction 2 Reaction 3 Starting molecule Product

Metabolic Pathway

ALL Living Things from Bacteria to Humans Conduct METABOLISM Two Kinds of Metabolic Reactions: Catabolism = breakdown of large molecules into simple ones to produce energy. (release energy) Anabolism = build large molecules from simple molecules. (requires energy input)

Energy Coupling Living organisms have the ability to couple catabolic and anabolic reactions: Energy released by catabolic reactions is captured and used to make ATP from ADP and Pi ATP can be broken back down to ADP and Pi, releasing energy to power the cell’s anabolic reactions.

The Structure and Hydrolysis of ATP ATP (adenosine triphosphate) Is the cell’s energy shuttle Provides energy for cellular functions O CH2 H OH N C HC NH2 Adenine Ribose Phosphate groups - CH

The Structure and Hydrolysis of ATP Energy is released from ATP when the terminal phosphate bond is broken P Adenosine triphosphate (ATP) H2O + Energy Inorganic phosphate Adenosine diphosphate (ADP) P i

Cellular Work A cell does three main kinds of work Mechanical Transport Chemical Energy coupling is a key feature in the way cells manage their energy resources to do this work ATP powers cellular work by coupling catabolic reactions to anabolic reactions

How ATP Performs Work ATP + Glu ADP Solute NH2 NH3 P i P Motor protein (c) Chemical work: ATP phosphorylates key reactants P Membrane protein Motor protein P i Protein moved (a) Mechanical work: ATP phosphorylates motor proteins ATP (b) Transport work: ATP phosphorylates transport proteins Solute transported Glu NH3 NH2 + Reactants: Glutamic acid and ammonia Product (glutamine) made ADP

GLUCOSE METABOLISM the cornerstone of life neurons are especially dependent on glucose regulatory mechanisms: hyperglycemic hormones = glycogenolysis, gluconeogenesis hypoglycemic hormone = insulin

Protein Metabolism Deamination: removal of the amino group (NH2) leaving a acetyl molecule Transamination: Adding an animo group to pyruvic acid to produce any of the nonessential amino acids Protein Synthesis: Production of protein molecule using an RNA model. Protein catabolism: breaking down a protein into individual Amino Acids.

Lipid Metabolism Lipoproteins: surrounding triglycerides with apoproteins to make them more transportable in water Very low-density lipoproteins (VLDL’s) Low-density lipoproteins (LDL’s) High-density lipoprteins (HDL’s) Lipolysis: break down lipids Beta Oxidation: breaking a fatty acid into 2 carbon compounds Lipogenesis: formation of lipids from non-lipids