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 electrons6 protons6 neutrons
6 electrons6 protons8 neutrons
6 electrons6 protons7 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.•H20, NaCl, C6H1206
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-)
Transferof electron
Protons +11Electrons -11Charge 0
Protons +17Electrons -17Charge 0
Protons +11Electrons -10Charge +1
Protons +17Electrons -18Charge -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:
H20 -> 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.
• CO2 + H2O H2CO3
• H2CO3 CO2 + H2O
• 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?