CHAPTER 2: THE CHEMISTRY OF
LIFE
BIO 1 EOC REVIEW
ASHLEY COX
2.1 THE NATURE OF MATTER
1.
2.
3.
What three subatomic particles make up atoms?
How are all of the isotopes of an element similar?
What are the two types of chemical bonds?
ATOMS
•
•
•
The basic unit of matter.
•
Atoms have an equal number of protons and electrons so that their charges balance
out, making them electrically neutral.
The center of the atom, made up of protons(+) and neutrons(n), is the nucleus.
Electrons(-) orbit the nucleus. They’re attracted to the positive charge of the nucleus
but remain outside of it because of the energy of their motion.
ELEMENTS
• A pure substance that consists entirely of one type of atom.
• More than 100 elements are known, but only about two dozen are commonly
found in living organisms.
• Atomic number: # of protons
• Mass number: total # of protons and neutrons in nucleus
ISOTOPES
• Atoms of the same element that differ in their number of neutrons.
• Isotopes are identified by their mass number.
• Radioctive isotopes are isotopes whose nuclei are unstable and break down at
a constant rate over time.
IONIC BONDS
• Formed when one or more electrons are transferred from one atom to another.
• When an atom loses an electron, it becomes positively charged. When it gains
an electron, it becomes negatively charged.
• Ion: positively/negatively charged atoms.
COVALENT BOND
• When atoms share electrons instead of transferring them.
• Sharing 2 electrons is a single bond; 4 electrons a double bond; 6 electrons a
triple bond.
• Molecules are formed by covalent bonds, and they are the smallest unit of
most compounds.
VAN DER WAALS FORCES
• Attractions that develop between the oppositely charged regions of nearby
molecules.
• Weakest of all chemical bonds.
2.2 PROPERTIES OF WATER
• 1. Why are water molecules polar?
• 2. What are acidic solutions? What are basic solutions?
POLARITY
• Polar molecules’ charges are unevenly distributed; they have a partial positive
charge on one end and partial negative charge on the other end, like a
magnet.
HYDROGEN BONDS
• The attraction between a hydrogen with a partial positive charge and another
atom with a partial negative charge.
• Because water is a polar molecule, it’s able to form multiple hydrogen bonds.
COHESION & ADHESION
• Cohesion: an attraction between molecules of the same substance.
• Adhesion: attraction between molecules of different substances.
MIXTURES, SOLUTIONS, & SUSPENSIONS
• Mixture: composed of 2 or more elements/compounds that are physically
mixed but not chemically combined.
• Solution: 2 or more substances mixed together whose molecules are evenly
distributed.
- Solutes are the substances being dissolved, solvents are the substances that do
the dissolving.
• Suspension: mixture of water and undissolved materials.
PH SCALE
• Acids: any compound that forms hydrogen (H+) ions in solution. (levels 1-6)
• Anything with pH level of 7 is considered neutral.
• Bases: any compounds that produce hydroxide (OH-) ions in solution. (levels 814)
• Buffers: weak acids or bases that can react with strong acids and bases to
prevent sharp, sudden changes, in pH.
2.3 CARBON COMPOUNDS
• Macromolecules: large molecules formed by polymerization.
• Polymers are made up of many monomers.
CARBOHYDRATES
• Compounds made up of carbon, hydrogen, and oxygen (usually in a 1:2:1
ratio).
• Sugars, starches, cellulose; they are the main source of energy.
• Sugars are the monomers of starches; single sugars are monosaccharides;
multiple monosaccharides are polysaccharides.
LIPIDS
• Made up mostly of carbon and hydrogen atoms; any compounds that are
fatty acids or their derivatives.
• Used to store energy.
• Natural oils, waxes, steroids.
PROTEINS
• Made up of nitrogen, carbon, hydrogen, and oxygen; usually composed of
one or more amino acid chain.
• Every protein has a specific role, dictated by directions contained in DNA.
• Protein shape plays a large role in protein function.
NUCLEIC ACIDS
• Contains hydrogen, oxygen, nitrogen, carbon, and phosphorous; consists of
many nucleotides (A, T, G, C, U) linked in a long chain.
• DNA & RNA
• Each nucleotide has three parts: 5- carbon sugar, phosphate group, & a
nitrogenous base.
2.4 CHEMICAL REACTIONS AND ENZYMES
• 1. What happens to chemical bonds during chemical reactions?
• 2. How do energy changes affect whether a chemical reaction will occur?
• 3. Why are enzymes important to living things?
CHEMICAL REACTIONS
• A process that changes or transforms one set of chemicals into another.
• Reactant: element or compound that enters into a chemical reaction.
• Product: element or compound produced by a chemical reaction.
• Activation energy: the energy need to start a reaction.
CATALYSTS & ENZYMES
• Catalyst: substance that speeds up the rate of a chemical reaction.
• Enzyme: protein that acts as a biological catalyst.
• Substrate: reactant of an enzyme-catalyzed reaction.
-the active site of the enzyme and the substrate have complementary shapes
(lock-and-key)