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BIOCHEMISTRY
CHEMISTRY OF LIFE
• Elements: simplest form of a
substance - cannot be broken down
any further without changing what it is
• Ex. C, H, O, N, Fe
• 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
-
• Electrons are not present within the atom,
instead THEY REVOLVE AROUND THE
NUCELUS OF THE ATOM & FORM THE
ELECTRON CLOUD
PROTONS
NEUTRONS
+
-
ELECTRONS
+
-
ATOMIC # = 2 (PROTONS)
ATOMIC MASS = 4
(PROTONS &
NEUTRONS)
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
Elements and Life
• The cell is a COMPLEX CHEMICAL
FACTORY containing some of the same
elements found in the nonliving
environment.
• carbon (C), hydrogen (H), oxygen (O), and
nitrogen (N) are present in the greatest
percentages
TWO TYPES OF COMPOUNDS
•
Organic - Contain C&H 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
–
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
• IONS: Charged particles formed when
electrons are lost or gained
– Example: Na+
COVALENT BONDS
• Occur when electrons are
SHARED by atoms.
• ** In general, the more
chemical bonds a molecule
has the more energy it
contains
SHARING IS CARING!
FORMULA
•
•
•
The chemical symbols and numbers that
compose a compound ("recipe")
Structural Formula – Line drawings of the
compound that shows the elements in
proportion and how they are bonded
Molecular Formula – the ACTUAL
formula for a compound
C2H6O
Organic Compounds Found in
Living Things
Biochemistry Basics
CARBOHYDRATES
• Why are carbohydrates important?
• 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
in a 1:2:1 ratio
Monosaccharides (simple sugars)
• all have the formula C6 H12 O6
• all have a single ring structure
– (glucose is an example)
Disaccharides (double sugars)
• 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
– ex. disaccharide + H2O --->
monosaccharide + monosaccharide
C12 H22 O11 + H2 O ---> C6 H12 O6 + C6 H12 O6
Lipids (Fats)
• Why are lipids important?
• 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 – that are insoluble
in water
Lipids
• Lipids are formed from the
union of one glycerol molecule
and 3 fatty acids
• 3 fatty acids + glycerol ---->
(lipid)
• Lipids along with proteins are
key components of cell
membranes
PROTEINS
• contain the elements carbon, hydrogen, oxygen,
and nitrogen
• composed of MANY amino acid subunits
• The basic amino acid form has a carboxyl
group on one end, a methyl group that only
has one hydrogen in the middle, and a amino
group on the other end.
• Attached to the methyl group is a R group.
*R-Groups vary producing
different amino acids
*20 amino acids exist in
living things
Why are Proteins
important?
•
•
•
Growth and repair
Energy
Carrying out
chemical
reactions(enzymes)
Polypeptide (protein)
• composed of three or more amino acids linked
by synthesis reactions
• Examples of proteins include insulin,
hemoglobin, and enzymes.
• ** There are an extremely large number of
different proteins.
• The bases for variability include differences in
the number, kinds and sequences of amino
acids in the proteins
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
RNA (ribonucleic acid)
• directs cellular protein synthesis
• found in ribosomes & nucleoli