The Chemistry of Life
Biochemistry
=Branch of science that deals with
the chemical composition (makeup)
and processes of living things
I. Atoms
A. The basic unit of matter
(Matter = anything that has mass and takes up space)
B. There are three subatomic particles that
are combined to make each atom.
* Proton (+)
* Neutron (o)
Energy
Levels
1st = 2
2nd = 8
3rd = 18
* Electron (-)
move around nucleus in electron cloud
Nucleus (+)
C. Isotopes – Atoms of the same element with different
number of neutrons
1. Identified by mass number (atomic mass)
2. Ex.: Carbon-12; Carbon-13; Carbon-14
II. Elements
A. An element is a substance that
contains one type of atom
B. We can find
information about
all known elements
in the
Periodic Table
of Elements
C. Element Key
Atomic Number (+), (-)
1
H
Hydrogen
1.0079
Chemical Symbol
Element Name
Atomic Mass/ Mass Number
(+ ; o) (protons plus neutrons)
1. Atomic Number = number of protons in nucleus
a.
b.
All atoms of the same element have same atomic number
This number also equals number of electrons in electron
cloud
2. Atomic Mass = average of all the isotopes of that
element
3. Mass Number = number of protons and neutrons
that make up atom nucleus
• Equations to know:
– At. Mass = p + n
– At. No. = p = e
–e=p
p = protons
n = neutrons
e = electrons
D. All substances are made up of elements
1. On Earth 90 elements occur naturally
2. 25 elements are essential to living things
* Carbon ( C)
* Hydrogen (H)
* Oxygen (O)
* Nitrogen (N)
96 % of human body
III. Combining Atoms
A. When two or more atoms are combined a
molecule is formed
(O₂)
B. When two or more atoms of different
elements combine a compound is formed
(CO₂)
ALL COMPOUNDS ARE
MOLECULES, BUT NOT ALL
MOLECULES ARE
COMPOUNDS!!!!!!
Be able to explain this statement.
C. We can describe the composition of compounds
by using a chemical formula
Ex: H₂O (2 atoms of hydrogen, 1 atom of oxygen)
C₆H₁₂O₆ (6 carbon, 12 hydrogen, 6 oxygen)
• The chemical properties of each compound
are different from each of the elements that
form it.
• Chemical properties = characteristics
– Ex: Sodium (Na) – silver metal, soft, reacts violently
with water
• Chlorine (Cl) – poisonous, green gas
---------------------------------------------------------------------
• Sodium Chloride (NaCl) or table salt
– White solid, dissolves easily in water, essential for
survival of living things
IV. Chemical Bonds
A. Bonds : a force that holds atoms together
1. Covalent Bonds
a. Forms when atoms share electrons
•
•
•
Share 2 = single bond
Share 4 = double bond
Share 6 = triple bond
b. Ex: water
2. Ionic Bonds
a. Formed when atoms lose or gain electrons
b. Creates electrically charged atoms called
ions (different number of protons/electrons)
* if atom loses electron = + ion
* if atom gains electron = - ion
c. Ions with opposite charges are attracted to
each other.
d. Ex: NaCl
3. Hydrogen Bonds
a. Form when the positive end of one
molecules is attracted to the negative end
of another molecules
b. Form without the interaction of electrons
c. Responsible for the cohesion of water
*allows raindrops to form or water to bead
d. Easily broken
V. Mixtures and Compounds
A. Mixture: two or more substances that are not
chemically combined
1. Heterogeneous: components not evenly mixed; all
components keep their own identity
Example: sand, salad, soup
2. Homogeneous: components
are evenly mixed; cannot see
each component; also called
solution
Example: kool-aid, air
3. Components of a mixture can be separated by
physical means, while components of a
compound must be separated by chemical means.
B. Parts of a Solution
1. Solute: substance being dissolved
2. Solvent: substance doing the dissolving
C. Suspensions
1. form when some materials do not dissolve
2. ex: blood – mostly H₂O, dissolved compounds, cells,
and misc. particles
VI. Acids/Bases/pH
A. Acids – a solution with a high concentration
of Hydrogen ions (H+)
B. Bases – a solution with a high concentration
of hydroxide ions (OH-)
C. pH – means potential for hydrogen
1. pH Scale: a measurement system used to indicate the
concentration of H+ ions
ranges from 0 - 14
– 0.1 – 6.9 = acid (pop, juice, coffee)
– 7. 0
= neutral (pure water)
– 7.1 – 14 = base (blood, soap, some cleaning products)
7.0
pure water
pH can determine what type of organisms can live in an
environment or what types of chemical reactions can take
place
Balancing Equations
2 H₂ + O₂ → 2 H₂O
Steps to Solve Equation
1. write down elements on reactants side
2. write down elements on product side
3. write number of atoms for each element on
each side
4. Begin adding coefficients to balance equation
Practice Problems
1. ____ N₂ + ____ H₂ → ____ NH₃
2. ____ Cu₂O + ____ C → ____ Cu + ____CO₂
3. ____ Mg + ____ O₂ → ____MgO
4. ____CH₄ + ____ O₂ → ____CO₂ + ____ H₂O
5. ___ Zn + ____ CrCl₃ → ____CrCl₂ + ____ZnCl₂
6. ___ CO₂ + ___ H₂O → ____C₆H₁₂O₆ + ____ O₂
7. ____C₂ + ____H₂ + ____OH → ____C₃H₇OH
8. ____C₃ + ____H₂O → ____C₉H₈O₄
9. ____O₂ + ____Cl₂S₃ → ____Cl₂O₄ + ____ SO₂
10. ____N₂ + ____H₂ + ____Cl₃ → ____NH₄Cl
ORGANIC CHEMISTRY
I. Organic chemistry is the study of compounds
that contain bonds between carbon atoms
A. Carbon atoms have 4 valence electrons;
therefore, each electron can join with electrons
from another atom to form strong covalent
bonds
B. Carbon can bond with:
* Hydrogen (H)
* Oxygen (O)
* Nitrogen (N)
* Phosphorus (P)
* Carbon (C)
* Sulfur (S)
C. Carbon can form chains of unlimited lengths
II. Organic Compounds Found in All
Living Things
A. Carbohydrates
B. Lipids
C. Proteins
D. Nucleic acids
A. Carbohydrates
1. Made up of C, H, and O in a 1 : 2 : 1 ratio
2. Uses
a. Energy (quick)
b. Structural building blocks (cellulose – plant cell walls)
3. Sugars and Starches
a. Monosaccharides (one)
b. Disaccharides (two)
c. Polysaccharides (many)
Monosaccharides
i. Simple sugar
ii. Chemical formula: C₆H₁₂O₆
iii. Ex: Glucose, Fructose, and Galactose are 3
isomers of a monosaccharide
= molecules with same chemical formula
but different structure
Disaccharides
i. A two-sugar molecule
ii. When 2 carbohydrate monomers are joined, a
dehydration synthesis(removal of H₂O) takes place
to form a disaccharide.
iii. Chemical formula: C₁₂H₂₂O₁₁
iv. Ex: glucose + galactose → Lactose
v. When disaccharides are used for energy, they are
digested by enzymes that break them up into
monosaccharides which are metabolized in the
process of cellular respiration
• Hydrolysis Reaction
glucose + galactose → Lactose
(C₆H₁₂O₆)
+
(C₆H₁₂O₆)
- (H₂O) = C₁₂H₂₂O₁₁
• Monomer = a single unit/molecule
• To digest lactose (sugar in dairy), you need
lactase enzyme
• Lactose intolerant people can’t produce
lactase
Polysaccharides
i. Large macromolecules or polymers that can
consist of hundreds or thousands of
monomers (C₆H₁₀O₅)n
1. Starches (plant: corn & wheat)
a. Amylase (enzyme) breaks it down into
monomers which are absorbed into the
bloodstream to be used by the cells.
2. Glycogen (animal starches)
a. Stored in the liver and muscles when there is excess
monosaccharides
3. Cellulose
a. Can not be digested = roughage
B. Lipids
1. Made up mostly of C and H with some O
2. Uses:
a. Energy – 2x the amount of chemical energy per
gram compared to carbohydrates
b. Making biological membranes
Ex: plasma membrane in cells
c. Water proof coverings in plants
d. Physical & thermal insulation to animals
3. Lipids are generally insoluable in water
4. Formed when a glycerol molecule (C₃H₅O₃)
joins a fatty acid
a. Saturated fats form when each carbon atom in
the fatty acid chain is joined to another carbon
atom by a single covalent bond
•
•
Solid at room temperature
Ex: butter
b. Unsaturated fats form when there
is a least one
carbon-carbon double bond
•
•
liquid at room temperature
Olive oil
c. Polyunsaturated fats form when there are two or
more carbon-carbon double bonds
•
•
liquid at room temperature
Corn, sesame & peanut oil
d. Steroids are lipids whose C, H, and O atoms
are arranged in rings
•
Estrogen, Androgen, Cholesterol
C. Proteins
1. Made up of C, H, O, and N
2. Uses:
a. Regulate cell processes and control
reaction rates
b. Make up bulk of all solid material in the
body (muscle, bone, skin, hair)
c. Transport substances in and out of cell
3. Proteins are polymers of amino acids
a. Amino acids are compounds
with an amino group (NH₂) at
one end and a
carboxyl group (COOH)
at the other.
b. There are 20 different amino acides
c. Amino acids are joined together by peptides
bonds to form a dipeptide or a polypeptide
molecule
4. Enzymes are proteins that are formed during
the process of protein synthesis
a. Enzymes are biological catalysts that control the
rate of chemical reactions.
b. Each type of enzyme catalyzes only one type of
reaction.
c. Names of enzymes usually end in –ase and are
named for the reaction they catalyze.
Example: lactase → lactose
protease → protein
D. Nucleic Acids
1. Made up of C, H, O, N, and P
2. Uses:
a. Store and transmit genetic information
b. Make proteins
3. Made up of nucleotides
a. 5 – Carbon sugar
b. Phosphate group
c. Nitrogenous base
4. Example: DNA and RNA