MODERN BIOLOGY
Ch. 2:1 Chemistry
MATTER: Chemical changes in matter are essential to all
life processes.

Matter: Anything that occupies space and has mass.

Mass: The quantity of matter an object has.
ELEMENTS AND ATOMS

Elements are substances that cannot be broken down
chemically into simpler kinds of matter.

>90% of all kinds of living things are made of
combinations of 4 elements:
o OXYGEN (O2)
o CARBON (C)
o HYDROGEN (H2)
o NITROGEN (N)

Periodic Table of the Elements
o Atomic number:
o Chemical symbol:
o Atomic mass:

Atom: the simplest particle of an element that retains
all of the properties of that element

Protons:

Neutrons:

Electrons:

Orbital:

ion:

isotope:
COMPOUNDS

The physical and chemical properties differ between
the compounds and elements that compose them.
For example:
o Sodium (Na) is a soft metal that explodes
when placed in water.
o Chlorine (Cl) is a green poisonous gas.
o Sodium Chloride (NaCl) is table salt.

All atoms are neutral.

Most atoms are unstable. (Noble gases are stable as
atoms. They do not react.)

Atoms combine (react) to become stable.

Atoms become stable when their outermost energy
level is “full” of electrons. They will:
o share electrons equally
o share electrons unequally
o transfer electrons completely with another
atom (gain or loss but no sharing)

The number and arrangement of their electrons
determine the way that elements combine.

Elements are arranged on the periodic table by the
number of valence electrons and the number of
energy levels that they have. Understand the periodic
table so you can learn how compounds are made.

Covalent Bonds: electrons are either shared equally
or unequally (co- sharing; -valent: outermost
electrons). Atoms in a molecule stay together to
maintain stability.

Ionic Bonds: electron(s), given up or accepted
completely; elements in the compound ionize (ionic
bond). Atoms (ions) in a compound stay together
because opposite charges attract.
Review Questions:
1. Carbon has an atomic number of 6.
How many p+ and e- does an atom of
carbon have?
2. Sodium is in family I, therefore, it has 1
valence e-. What will Naº do to
become stable?
Challenge
3. If Aluminum gives up it’s 3 valence e- to
chlorine atoms, what are the resulting
charges on the ions of Al and each Cl
(AlCl3)?
4. Oxygen is in family VI. It has 6 valence
e- and needs 2 more to become stable.
Draw an electron configuration diagram
(dot diagram) and count out the e- that
make each atom stable. (#3, pg.10 of
study guide)
5. An acetylene torch gives off lots of
energy. In fact, it us used to cut steel
plate. The formula for acetylene is
C2H2, and there is a triple bond
between the carbon atoms. Draw in
the e- where the ? are located below.
(C = Family IV; H = Family I)
H?C?C?H
MODERN BIOLOGY
Ch. 2:2 ENERGY
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ENERGY & MATTER
Energy: The ability to do work.
States of Matter: solid, liquid, gas

Average Kinetic Energy = temperature

K.E. of atoms > from solid  liquid  gas
ENERGY AND CHEMICAL REACTIONS

Chemical reaction: CO2 + H20  H2CO3
Reactants  Products


Metabolism: the sum of all the chemical reactions in an organism.
Activation Energy: Amount of energy needed to make a reaction begin. Abbrev = E act
Enzymes

Made of protein

biological catalysts

reduce the Eact to cellular temperatures

speeds the reaction to maintain life
An energy diagram comparing a reaction (A + B  C + D)
with and without an enzyme.
Metabolism involves “coupled” reactions.
Energy
Producing
Downhill
Catabolic
Exothermic
Energy
Consuming
Uphill
Anabolic
Endothermic
MODERN BIOLOGY
Ch. 2.3
Water, Solution, pH
Polarity: “Electron hogs and electron weaklings”
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
In covalent bonds where the “sharing” is unequal (like in
water).

This creates a shift in the electron cloud around the
stronger atom making it partially negative (-).

The shift also partially exposes the proton of the hydrogen
making the hydrogen areas partially positive (+).

This makes water a polar (think of the + and – poles on a
magnet) covalent (shared valence electrons) molecule.
Solubility of Water:

The polar nature of water allows it to dissolve polar
substances (sugars), ionic compounds (salts), and some
proteins.

Water does not dissolve nonpolar molecules (no poles /
equal sharing: like O2).

“Like dissolves like.”
Hydrogen Bonding ( opposites attract too.)

The force of attraction between the + area of one
molecule and the - area of neighboring molecules.

Hydrogen Bonding accounts for the unique properties of
water.
o cohesion: water sticks to itself (a glass of water
fuller than full.)
o adhesion: water sticks to other things (meniscus)
o temperature moderation or the ability to absorb
and release large amounts of heat with only slight
changes in its own temperature:

moderation between day / night

summer / winter

coastal vs. inland climates

global moderation 
o evaporative cooling
o density of ice
Solutions

Solute into solvent makes a solution.
o Salt in water makes a salt solution.
o Alcohol in water makes a solution.
o (Solvent: whichever is in greater quantity)

Concentration: the amount of solute in a volume of
solvent.
o 2g salt diluted up to 100 ml with water = 2% salt
solution

saturated solution: no more solute can dissolve.

Aqueous solutions: water is the solvent
Acids and Bases

Ionization of Water: H2O  H+ + OH- (hydrogen ion and
hydroxide ion) water is neutral in pH.

OR H+ + H2O  H3O+ (hydronium ion)

Acid: substances that put H+ into solution

Base: substances that put OH- into solution.

pH: range is 0 to 14.
o Near zero is very acidic
o Near 14 is very alkaline or basic.
o 7 is neutral (an equal # of H+ and H3O+ )

Buffers: neutralize small amounts of acid or base
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MODERN BIOLOGY
Ch. 3 “Biochem”
Class Notes
Ch. 3.1 Carbon
Carbon Bonding

Two categories of compounds:
o Organic: made mostly of carbon
o Inorganic: mostly without carbon

Carbon’s versatility:
o Family IV makes 4 covalent bonds so it can bond with other elements but, more
importantly, with other carbons. This creates enormous variety:

straight carbon chains

branched carbon chains

carbon rings

double and triple bonds

Large Carbon Molecules
o monomers  polymers: by condensation reactions. H+ and OH- are removed to
create bonding sites. This makes water. see p.53
Energy Currency

Adenosine Triphosphate or ATP

A--PPP

-- = low-energy bond;  = high-energy bond

P is transferred to other molecules.
When the bond breaks, energy is given off to do
work, like make muscles contract.
Ch. 3.2 Molecules of Life: Macromolecules
Carbohydrates: carbon, hydrogen, and oxygen. 1:2:1

Monomer = monosaccharide (simple sugar) (CH2O)n where n = 3 - 8. A six-carbon
monosaccharide would be C6H12O6. Most common examples:
o glucose: main source of energy in cells
o fructose: fruit sugar and the sweetest
o galactose: milk

Because all of the simple sugars (say, 6C sugars) have the same chemical formula but
different structural formulas (built differently) they have slightly different chemical
properties and are called isomers.

Disaccharides: double sugar

Polysaccharides: several to hundreds of simple sugars put together.
o glycogen: animal sugar storage (short-term) in liver and muscles for quick
use.
o starch: plant sugar storage
o cellulose: support
Proteins: carbon, hydrogen, oxygen, and nitrogen

Monomer = amino acids (20 different) works like our alphabet to create variation.
o Each A.A. has an amino group and a carboxyl group. They differ in their side
chains.

dipeptides and polypeptides and created by condensation reactions. see “Large
Carbon Molecules” above. The resulting bond is a peptide bond.

Enzymes: are biological catalysts
o most are protein
o Induced-fit model (fig 3-9; p.57)

substrate

active site

optimal conditions

lose shape/lose function
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Lipids: do not dissolve in water (polar) so they are nonpolar. “Like dissolves like”.

Lipids store more energy per gram than other macromolecules.

Fatty acids: long, straight chains of carbon and hydrogen with a functional group at one end.
If the carbons have all single bonds then it is saturated with hydrogen: a saturated fat.
If the carbons have any double bonds then it is unsaturated fat.

Triglycerides: glycerol + 3 fatty acid chains.
o If it contains saturated fatty acids then it is saturated fat like meat fat or butter
(animal fat).
o Unsaturated triglycerides are oil (plant fat).

Phospholipids: glycerol + 2 fatty acid chains + phosphate group.
o phosphate head is polar like water
o lipid tails are nonpolar and repel water.
o phospholipids bilayer see p. 59

Waxes: structural lipid: long fatty acid chain + long alcohol chain. Protects plants from
drying out and ear wax for protection from microorganisms.

Steroids: four fused carbon rings + various functional groups attached to the rings.
o cholesterol is starting point to make testosterone, estradiol (sex hormones)
o needed for nerve cells
o cell membrane component
Nucleic Acids: DNA, RNA

Monomer: nucleotides (phosphate, sugar, base)

DNA: heredity, cell control

RNA: messenger, transport, organization.

see fig 3-12, p.60
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