Chemistry

Mitochondria and Oxidative Phosphorylation Controlled oxidation of sugars Breaks down sugar in a number of small stepwise events = more efficient NADH and FADH2 carry energy in the form of high energy electrons Produce these molecules as a way to transport high energy electrons (Energy is stored as redox potential) These electrons will be transferred to the electron transport chain Glycolysis occurs in a stepwise process NADH is an energy carrier (energy will be harvested later) Some ATP is produced directly Most of the energy is still stored in pyruvate molecules Citric acid/tricarboxylic acid/Krebs cycle Oxidize pyruvate Yield for every 2 molecules of acetyl CoA: 2 GTP + 2 FADH2 + 6 NADH + 4 CO2

Protein Function and Enzymes Most proteins function by binding to other molecules Antibody - aggregating foreign Actin - binding to itself Enzymes Hexokinase - binding pocket for glucose, then catalyze Selectivity comes into play based on functional groups Proteins bind other molecules at the binding site Unique chemical environment Not only based on agreeing shape, but also non-covalent bonds In some cases this binding is very tight; in others it is weak and short lived. The binding site is a cavity on the surface created by several amino acids that interact with the substrate Chemical identity of function groups that dictates what molecules will bond Protein binding to another molecule is highly selective Thermal energy causes not matching molecules to dissociate

Chemical Components of Cells - Part I: Sugars 1/14 Living organisms are chemical systems Cells contain relatively few elements The distribution of elements differs dramatically from living organisms to inanimate matter Mostly carbon, nitrogen, oxygen, and hydrogen Why do living organisms contain so much hydrogen and oxygen? Water is the most abundant molecule in the cell Atoms can interact with each other through covalent and non-covalent bonds MOLECULES ARE COVALENTLY BONDED ATOMS Result from the sharing of electrons & form the backbone of molecules Strong molecular bonds that require energy to make and break The number of electrons in the outer shell determine reactivity* Not always shared equally (i.e. Polar vs non-polar molecules)