BIOCHEMISTRY
CHEMISTRY OF LIFE*
• Elements: simplest form of a
substance - cannot be broken down
any further without changing what it is
• Atom: the actual basic unit composed of protons, neutrons, and
electrons
THE ATOM*
• Just like cells are the basic unit of life, the
ATOM is the basic unit of matter.
• They are very small. If placed side by side
one million would stretch a distance of 1cm.
• The atom is made up of 3 particles.
Particle
Charge
PROTON
+
NEUTRON
NEUTRAL
ELECTRON
-
ISOTOPES*
•
•
•
atoms of the same element that HAVE A
DIFFERENT NUMBER OF NEUTRONS
Some isotopes are radioactive. This means
that their nuclei is unstable and will break
down at a CONSTANT RATE over time.
There are several practical uses for
radioactive isotopes:
1. CARBON DATING
2. TRACERS
3. KILL BACTERIA / CANCER CELLS
COMPOUNDS*
• a substance formed by the chemical
combination of 2 or more elements in definite
proportions
– Ex: water, salt, glucose, carbon dioxide
TWO TYPES OF COMPOUNDS
•
Organic - Contain C, H, and O in some
ratio (usually referred to as chemicals of
life)
–
•
Carbohydrates, Proteins, Lipids, Nucleic Acids
Inorganic - usually "support" life - no
specific ratio of C, H, and O
–
Water (H2O), Carbon Dioxide (CO2)
CHEMICAL BONDS
• Chemical bonds hold the atoms in a
molecule together.
• There are 2 types of chemical bonds
IONIC and COVALENT
IONIC BONDS*
• Occur when 1 or more electrons are
TRANSFERRED from one atom to another.
• When an atom loses an electron it is a
POSITIVE charge.
• When an atom gains an electron it is a
NEGATIVE charge
• These newly charged atoms are now called
IONS
– Example: NaCl (SALT)
COVALENT BONDS*
• Occur when electrons are SHARED by atoms.
• These new structures that result from covalent
bonds are called MOLECULES
• ** In general, the more chemical bonds a
molecule has the more energy it contains
SHARING IS CARING!
SOLUTION*
Two parts:
• SOLUTE – SUBSTANCE THAT IS
BEING EVENLY DISSOLVED (SUGAR /
SALT)
• SOLVENT - the substance in which the
solute dissolves
MIXTURES*
• Water is not always pure. It is often found as
part of a mixture.
• A mixture is a material composed of TWO OR
MORE ELEMENTS OR COMPOUNDS THAT
ARE PHYSICALLY MIXED
– Ex: salt & pepper mixed, sugar and sand – can be
easily separated
WATER*
• Covalently bonded compound
• Due to being a polar covalent bound, can interact
with a maximum 4 other water molecules through
hydrogen bonding
• Due to this property has very unique properties
1. Cohesion, think surface tension
2. Adhesion, capillary action, climbing up plants from soil
to top of trees or water soaking paper towel
• Other unique properties
1. 1-99 Celsius or 33-212 Fahrenheit in liquid state.
2. Floats when a solid
ACIDS & BASES*(pH Lab)
•
Acids: always (almost) begin with "H" because
of the excess of H+ ions (hydrogen)
–
Ex: lemon juice (6), stomach acid (1.5), acid rain
(4.5), normal rain (6)
Facts about Acids
• You eat acids daily (coffee, vinegar, soda,
spicy foods, etc…)
ACIDS & BASES
• Bases: always (almost) end with -OH because
of the excess of hydroxide ions (Oxygen &
Hydrogen)
– EX: oven cleaner, bleach, ammonia, sea water,
blood, pure water
Facts about Bases
• Bases turn litmus BLUE.
pH SCALE*
• measures degree of
substance alkalinity or
acidity
• Ranges from 0 to 14
• 0 – 5 strong acid
• 6-7 neutral
• 8-14 strong base
• The goal of the body is to maintain
HOMEOSTASIS (neutrality) – to do this when
pH is concerned, we add weak acids & bases to
prevent sharp changes in pH.
• These are called BUFFERS
– Water
– Protein
– Kidneys
CARBOHYDRATES*
(Cereal Investigation Lab)
• Living things use carbohydrates as a key source
of ENERGY!
• Plants use carbohydrates for structure
(CELLULOSE)
– include sugars and complex carbohydrates
(starches)
– contain the elements carbon, hydrogen, and oxygen
(the hydrogen is in a 2:1 ratio to oxygen)
Monosaccharides (simple sugars)
• all have the formula C6 H12 O6
• all have a single ring structure
– (glucose is an example)
Disaccharides (double sugars)
• all have the formula C12 H22 O11
• sucrose (table sugar) is an example
Polysaccharides
•
•
•
•
Formed of three or more simple sugar units
Glycogen - animal starch stored in liver & muscles
Cellulose - indigestible in humans - forms cell walls
Starches - used as energy storage
How are complex
carbohydrates formed
and broken down?
Dehydration Synthesis
• Combining simple molecules to form a more
complex one with the removal of water
– ex. monosaccharide + monosaccharide ---->
disaccharide + water
– (C6H12O6 + C6H12O6 ----> C12H22O11 + H2O
• Polysaccharides are formed from repeated
dehydration syntheses of water
– They are the stored extra sugars known as starch
Hydrolysis
• Addition of WATER to a compound to
SPLIT it into smaller subunits
– (also called chemical digestion)
– ex. disaccharide + H2O --->
monosaccharide + monosaccharide
C12 H22 O11 + H2 O ---> C6 H12 O6 + C6 H12 O6
Lipids (Fats)*
• Fats, oils, waxes, steroids*
• Chiefly function in energy storage, protection,
and insulation*
• Contain carbon, hydrogen, and oxygen but the
H:O is not in a 2:1 ratio
• Tend to be large molecules -- an example of a
neutral lipid is below
• Neutral lipids are formed from the union of one
glycerol molecule and 3 fatty acids
• 3 fatty acids + glycerol ----> neutral fat (lipid)
• Fats -- found chiefly in animals
• Oils and waxes -- found chiefly in plants
• Oils are liquid at room temperature, waxes are
solids
• Lipids along with proteins are key components of
cell membranes
• Steroids are special lipids used to build many
reproductive hormones and cholesterol
PROTEINS*
• contain the elements carbon, hydrogen,
oxygen, and nitrogen
• composed of MANY amino acid subunits
• It is the arrangement of the amino acid that
forms the primary structure of proteins.
• The structure of proteins informs of their
function
Major Protein Functions*
•
•
•
•
Growth and repair
Lower chemical reactions energy
requirements (like lowering the time, or
intensity of the stove fire to cook meat)
Buffer -- helps keep body pH constant
Energy (little amount, most come from
carbohydrates)
NUCLEIC ACIDS*
•
•
•
•
•
•
•
in all cells
composed of NUCLEOTIDES
store & transmit heredity/genetic information
Nucleotides consist of 3 parts*:
1. 5-Carbon Sugar
2. Phosphate Group
3. Nitrogenous Base
DNA (deoxyribonucleic acid)*
• contains the genetic code of instructions that direct a
cell's behavior through the synthesis of proteins
• found in the chromosomes of the nucleus (and a few
other organelles)
RNA (ribonucleic acid)*
• directs cellular protein synthesis
• found in ribosomes & nucleoli
CHEMICAL REACTIONS*
• a process that changes one set of chemicals into
another set of chemicals
• REACTANTS – elements or compounds that
enter into a chemical reaction
• PRODUCTS – elements or compounds that are
produced in a chemical reaction
• Chemical reactions always involve the breaking of
bonds in reactants (Hydrolysis) and the formation
of new bonds in products. (Synthesis)
Enzymes and Enzyme Action
• catalyst: inorganic or organic substance which
speeds up the rate of a chemical reaction without
entering the reaction itself
• Enzymes*: organic catalysts made of protein
• most enzyme names end in -ase
• enzymes lower the energy needed to start a
chemical reaction. (activation energy)
enzyme
substrate (reactants) -------------> product
Factors Influencing Rate of Enzyme
Action * (Recall Potato Lab)
1. pH - the optimum (best) in most living things is
close to 7 (neutral)
• high or low pH levels usually slow enzyme activity
• A few enzymes (such as gastric protease) work
best at a pH of about 2.0
2. Temperature - strongly influences enzyme
activity
• optimum temperature for maximum enzyme
function is usually about 35-40 C.
• reactions proceed slowly below optimal
temperatures
• above 45 C most enzymes are denatured
(change in their shape so the enzyme active site
no longer fits with the substrate and the enzyme
can't function)
3. Concentrations of Enzyme and Substrate
• ** When there is a fixed amount of enzyme and
an excess of substrate molecules -- the rate of
reaction will increase to a point and then level
off.