The Chemistry of Life

Atoms The basic unit of matter Greek, atomos meaning “unable to cut” Named after Democritus...there has to be a limit =atom.

Atoms What does an atom consist of? Subatomic particles: protons (+), neutrons, and electrons (-). What is the center of an atom called? Nucleus Where do we find electrons? Constant motion surrounding the nucleus.

SUBATOMIC PARTICLES Why are atoms neutral despite having charged particles? Atoms have equal numbers of electrons and protons/have equal, but opposite charges. (they balance out)

Elements and Isotopes What is a chemical element? A chemical element is a pure substance that consists entirely of one type of atom (C, Na, H, N, O, etc.) What is an isotope? Atoms of the same element w/ different number of neutrons.

Isotopes of Carbon Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 8 neutrons 6 electrons 6 protons 7 neutrons Because they have the same number of electrons, all isotopes of an element have the same chemical properties.

Chemical Compounds What is a chemical compound? Substance formed by the chemical combination of two or more elements. H 2 0, NaCl, C 6 H

Chemical Bonds What are the main types of chemical bonds? Ionic & Covalent Ionic- electrons transfer from one atom to the other. Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na + ) Chloride ion (Cl - ) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1

Chemical bonds Covalent Bonds- electrons are shared b/w atoms = molecule. What molecule is this?

Hydrogen Bonds A single water molecule may be involved in as many 4 hydrogen bonds at the same time. Cohesion: attraction b/w molecules of the same substance. Adhesion: attraction b/w different substances. Meniscus

Properties of Water Water is polar: there is an uneven distribution of electrons b/w the oxygen and hydrogen atoms. Why is this important? Water can react to form ions: H 2 0 -> H + + OH - Hydrogen ion Hydroxide ion

Acids, Bases, and pH pH: ranges 0 to 14 Acids: contain higher [ ] of H + ions than pure water and have a pH below 7. Bases: contain lower [ ] of H + ions than pure water and have pH values above 7.

Buffers Weak acids or bases that can react w/ strong acids or bases to prevent changes in pH. Why is this important?

Carbon Compounds What is the difference b/w organic/inorganic chemistry? Carbon Carbon forms strong covalent bonds and can join other carbon atoms to from long chains (carbon-carbon bonds) Four valence electrons No others like it.

Macromolecules Four groups of organic compounds “Giant molecules” Carbohydrates (starch and sugar) − Living things main source of energy − Monosaccharide's/polysaccharides, “ose” Lipids (cooking oil) − Mostly CH, used to store energy − Saturated, unsaturated Nucleic Acids (RNA & DNA) (CHNOP) Proteins (polymers of amino acids) (CHNO) − AA are compounds w/an amino group (-NH2) and a carboxyl group (-COOH), what distinguishes each AA?

Amino Acids General Structure

Recognizing Macromolecules Organic or Inorganic? Nucleic Acid Glucose Lipids

Chemical Reactions & Enzymes Why are chemical reactions important? Chemical reaction: a process that changes into another set of chemicals. CO 2 + H 2 O H 2 CO 3 H 2 CO 3 CO 2 + H 2 O What are reactants? What are products? Chemical reactions always involve the breaking of bonds in reactants and the formation of new bonds in products.

Energy in Reactions To stay alive organisms need to carry out reactions. Growing, breathing, think, etc. Activation energy: the energy needed to get a RxN started. Can you tell which is an energy absorbing reaction/energy releasing reaction?

Enzymes Some chemical reactions are too slow... Catalyst: substance that speeds up the rate of a chemical reaction; lowers activation energy Enzymes (“ase”) are biological catalyst; speed up chemical reactions that take place in the cell. Lipase Carbonic anhydrase Amylase

Enzyme Action How do they work? Enzyme-Substrate Complex The reactants of enzyme-catalyzed reactions are known as substrates. Not random; active site and substrate fit like “lock and key” What happens after? What factors affect enzyme function?