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Chapter 2 Chemical Elements
Chemistry as it related to biology
A. Matter
1. Matter takes up space and
has mass.
2. All living and nonliving matter
is composed of 92 naturallyoccurring basic elements
(Periodic Table)
3. Elements cannot be broken
down to substances with
different chemical or physical
properties.
4. Six elements (C, H, N, O, P,
S) make up 98% of living
things.
B. Atomic Structure
1. Chemical and physical properties of atoms (e.g., mass)
depend on the subatomic particles.
a. Different atoms contain specific numbers of protons,
neutrons, and electrons.
b. Protons and neutrons are in nucleus of atoms; electrons
move around nucleus.
c. Protons are positively charged particles; neutrons have no
charge; both have about 1 atomic mass unit of weight.
d. Electrons are negatively charged particles.
2. The atomic mass of an atom is about equal to
the sum of its protons and neutrons.
3. All atoms of an element have the same number
of protons, the atom's atomic number.
C. Isotopes
1. Isotopes are atoms with the same number of
protons but differ in number of neutrons; e.g., a
carbon atom has six protons but may have more or
less than usual six neutrons.
Carbon 14 - Break it Down!
Carbon- 12 is the most common form of carbon, it has 6 protons,
6 electrons, and 6 neutrons
It is called Carbon 12 because that is its weight (6 + 6 )
Carbon 14 has 2 extra neutrons, its weight is 14 (6 + 8 ); it is an
isotope of carbon
A. Compounds
1. When two or more different elements react or
bond together, they form a compound (e.g., H2O).
2. A molecule is the smallest part of a compound
that has the properties of the compound.
3. Electrons possess energy and bonds that exist
between atoms in molecules contain energy.
B. Ionic Bonding
1. Ionic bonds form when electrons are
transferred from one atom to another.
2. Losing or gaining electrons, atoms
participating in ionic reactions fill outer shells,
and are more stable.
3. Example: sodium with one less electron
has positive charge; chlorine has extra
electron that has negative charge. Such
charged particles are called ions.
4. Attraction of oppositely charged ions holds
the two atoms together in an ionic bond.
C. Covalent Bonding
1. Covalent bonds result when two atoms
share electrons so each atom has octet of
electrons in the outer shell.
2. Hydrogen can give up an electron to
become a hydrogen ion (H+) or share an
electron to complete its outer shell of two
electrons.
3. Structural formulas represent shared
atom as a line between two atoms; e.g.,
single covalent bond (H-H), double covalent
bond (O=O)
Nonpolar and Polar Covalent Bonds
1. In nonpolar covalent bonds, sharing of electrons is equal.
2. With polar covalent bonds, the sharing of electrons is unequal.
a. In water molecule (H2O), sharing of electrons by oxygen and
hydrogen is not equal; the oxygen atom with more protons
dominates the H2O association.
*The oxygen then assumes a small negative charge *
Hydrogen Bonding
1. A hydrogen bond is weak attractive force between slightly positive
hydrogen atom of one molecule and slightly negative atom in
another or the same molecule.
2. Many hydrogen bonds taken together are relatively strong.
3. Hydrogen bonds between complex molecules of cells help
maintain structure and function.
Hydrogen bonds create
surface tension.
Water is the universal solvent, facilitates chemical reactions
both outside of and within living systems..
a. Water is a universal solvent because it dissolves a great
number of solutes.
b. Ionized or polar molecules attracted to water are
hydrophilic.
c. Nonionized and nonpolar molecules that cannot attract
water are hydrophobic.
Solvents dissolve
other substances
(solutes) and do not
lose their own
properties.
Acids and Bases
1. Covalently bonded water molecules ionize; the
atoms dissociate into ions.
2. When water ionizes or dissociates, it releases a
small (107 moles/liter) but equal number of H+ and
OH- ions; thus, its pH is neutral.
3. Water dissociates into hydrogen and hydroxide
ions:
4. Acid molecules dissociate in water,
releasing hydrogen ions (H+) ions:
HCl = H+ + Cl-.
5. Bases are molecules that take up hydrogen
ions or release hydroxide (OH-) ions:
NaOH = Na+ + OH-.
6. The pH scale indicates
acidity and basicity (alkalinity)
of a solution.
1) One mole of water has 107
moles/liter of hydrogen ions;
therefore, has neutral pH of 7.
2) Acid is a substance with pH
less than 7; base is a
substance with pH greater than
7.
3) As logarithmic scale, each
lower unit has 10 times the
amount of hydrogen ions as
next higher pH unit;
* Buffers keep pH steady and within
normal limits in living organisms.
Mixing Things Up
• Mixture - a physical combination of 2 or more
things without chemically combining them.
– Example:
• Solution – a physical combination of 2 or more
things with chemically combining them.
– Example:
• Suspension – Mixture of elements that do not
dissolve, instead separate into small particles.
– Example:
SOLUTIONS
• Parts of a solution are as
follows:
– Solute: the substance
being dissolved
• Chemically changed
– Solvent: the substance in
which the solute is
dissolved
• Not chemically changed
Solutions can be Pure
(Homogeneous) or
Mixed (Heterogeneous)
Heterogeneous
solutions do not have
the same
composition through
out the solution while
homogeneous
solutions have the
same composition
through out.
Colloids are a
mixture in which the
particles are
dispersed throughout
but are not heavy
enough to settle out
Macromolecules
• A macromolecule is a
very large molecule
commonly created by
polymerization of smaller
subunits. In biochemistry,
the term is applied to the
four conventional
biopolymers (nucleic
acids, proteins,
carbohydrates, and lipids)
• polymerization
is a process of
reacting monomer
molecules
together in a
chemical reaction
to form polymers
Each ring
represents a
monomer,
linked together
they make a
polymer, and
eventually they
form a
macromolecule
Carbohydrate are
• Any of a group of organic compounds that
includes sugars, starches, celluloses, and gums
and serves as a major energy source in the diet of
animals.
• They are produced by photosynthetic plants and
contain only carbon, hydrogen, and oxygen,
usually in the ratio.
• They are stored by the human body as fat
• Lipids:
• Any of a group of organic compounds, including
the fats, oils, waxes, sterols, and triglycerides.
• They are insoluble in water but soluble in
nonpolar organic solvents, are oily to the touch,
and together with carbohydrates and proteins
constitute the principal structural material of
living cells.
• Saturated fats
have all possible
bonds completed
• Unsaturated fats
have some open
bonds
Saturated are commonly solid form = Butter
Unsaturated are commonly liquid = Olive oil
• Nucleic acid:
• Any of a group of complex compounds found in
all living cells and viruses, composed of purines,
pyrimidines, carbohydrates, and phosphoric acid.
• Nucleic acids in the form of DNA and RNA
control cellular function and heredity.
• Protein:
• Any of a group of complex organic macromolecules that
contain carbon, hydrogen, oxygen, nitrogen, and usually
sulfur and are composed of chains of alpha-amino acids.
• Proteins are fundamental components of all living cells
and include many substances, such as enzymes,
hormones, and antibodies, that are necessary to the
functioning of an organism.
• They are essential in the diet of animals for the growth
and repair of tissue and can be obtained from foods such
as meat, fish, eggs, milk, and legumes.
• Made up of AMINO ACIDS group of 20 to pick from
ENZYMES
• Enzymes are large biological molecules
responsible for the thousands of chemical
interconversions that sustain life. They are highly
selective catalysts, greatly accelerating both the
rate and specificity of metabolic reactions, from
the digestion of food to the synthesis of DNA.
Most enzymes are proteins.
• Enzymes are proteins inside the cells.
• They are formed by special chains of amino acids
that come together in different shapes to do
special jobs, like breaking down sugar and fat
molecules or to make more enzymes.
• The cells need the enzymes to live, and each
different enzyme has its own work to do.
• When the body is missing a type of enzyme, the
cells can't work properly.
Enzymes are a lock where the substrate is the key. If the
wrong shape enzyme tries to be fit with the same substrate
it wont work.
ENZYMES ONLY DO ONE JOB!!! This is why we need
thousands of different enzymes to carry out a single days
body functions.
What can effect Enzymes?
• Only two things can effect how well enzymes
work.
– Temperature
– pH
Temperature will damage the enzyme and will make it
so the substrate will no longer fit correctly making it
not work at all
pH will limit how effective an enzyme is, you may need
more enzyme to do the same job when the pH for an
area is off.
Enzymes are
very pretty by
design but
each and
every ribbon
that mixes in
is part of
what makes it
have the
specific
function it is
designed for.
Naming Enzymes
• Protease: Breaks down protein into amino acids. Acts on
pathogens such as bacteria, viruses, and even cancerous
cells.
• Amylase: Breaks down complex carbohydrates (starches)
into simpler sugars such as dextrin and maltose.
• Lipase: Along with bile from the gallbladder, breaks down
fats and the fat-soluble vitamins A, D, E, and K.
• Cellulase: Breaks down the cellulose found in fruits,
vegetables, grains, and seeds.
• Pectinase: Breaks down pectin-rich foods such as citrus
fruits, apples, carrots, beets, and tomatoes.
• Lactase: Breaks down lactose, the complex sugar in
milk products
• Glucoamylase: Breaks down maltose, the sugar in all
grains, into two glucose molecules
• Cathepsin: Breaks down animal protein.
• Bromelain: Breaks down proteins found in plants and
animals. It can help the body to fight cancer, improve
circulation, and treat inflammation.
• Papain: Breaks down food protein and aids the body in
digestion.
Most enzymes have the ending ASE or IN, this
should help you identify what is an enzyme simply by
looking at its spelling