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?