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Organic Chemistry
Organic compounds contain the element carbon
Occur naturally only in living organisms or in their
products
Out of the 92 elements found in nature, only a few
are in organic compounds
• Inorganic compounds do not contain carbon
– Exception – carbon dioxide (CO2) and other carbonate
compounds (CO3)
– Examples – water, salts, acids,
bases
• Living organisms contain both organic and
inorganic compounds
– Water is the most important inorganic compound
Macromolecules
• Carbon atoms can be joined covalent into long
chains
– Straight chained molecules
– Branched molecules
– Ring molecules
• Most cells store small carbon compounds which
serve as building blocks for larger molecules
• Macromolecules – large molecules formed from
smaller organic molecules bonded together
– Four major categories:
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
• Polymer – molecules made from repeating units
of identical compounds (monomers) which are
bonded together
Carbohydrates
• Composed of:
– Carbon
– Hydrogen
– Oxygen
• Ratio of hydrogen to oxygen for each carbon
atom
(2 H : 1 O) – same as water
• General formula – (CH2O)n
– N represents the number of repeating units in the
chain
• Carbohydrate function
– Energy source
– Cellular structural support
• Ex. Cellulose in plant walls
• Ex. Chitin in exoskeletons of insects
• Simple sugars
– Have 3-7 repeating units
– Also known as a monosaccharide
– Chemical names ALWAYS end in -ose
– Ex. Glucose (C6H12O6) – essential energy
source for organisms
• Disaccharide
– Two simple sugars linked together
– Ex. Sucrose (table sugar) – additional
energy source for organisms
– Ex. Lactose – component of milk
• Dehydration Synthesis – sugar molecules
are bonded together by removing water
– Brought on in living cells by the action of
enzymes
– Important in forming the complex organic
compounds an organism needs
• Polysaccharide
– Three or more simple sugars linked together
(polymer)
– Ex. Glycogen – molecule form for storage of
glucose found in liver and skeletal muscle
• Hydrolysis
– Breakdown of disaccharides or
polysaccharides to yield simple sugars
Lipids
• Composed of:
– Carbon
– Hydrogen
– Oxygen (less than found in carbohydrates)
• Triglycerides:
– Fats
• Solid at room temperature
– Oils
• Liquid at room temperature
– Waxes
• Contains fatty acids and glycerol components
– Glycerol – 3 carbon chain with an OH group
bonded to each carbon
– Fatty acid – chain of carbon atoms with a
hydrogen or a carboxyl (-COOH) group bonded to
each carbon
• Dehydration (loss of water) combines 3 fatty acid
molecules and 1 glycerol molecule to produce a fat
or oil molecule
• Primary function – reserve of stored energy
• Examples:
– Stored in fat cells of your
body
– Used on leaves as waxes
to prevent water loss
– Used to compose structural elements like
honeycomb in a beehive (beeswax)
• Saturated versus unsaturated fats:
– Lipids can contain single or double bonds
– Saturated fats
• Solid at room temperature (fats or waxes)
• Contain SINGLE bonds between carbon
atoms
– Unsaturated fats
• Contain DOUBLE or TRIPLE bonds between
carbon atoms
• Liquids at room temperature (oils)
• Polyunsaturated – more than one double
bond
– Doctors recommend more unsaturated and
less saturated fats in your diet
• Phospholipids
– Plasma membrane
component
– Have hydrophobic and
hydrophilic regions
• Steroids
– Building block for vitamin D
and large hormones like testosterone and
estrogen
– Ex. Cholesterol
Proteins
• Composed of
– Carbon
– Hydrogen
– Oxygen
– Nitrogen
• Amino Acids
– Building block of a protein
– Consist of a central carbon atom bonded to
•1
•1
•1
•1
carboxyl group (COOH)
amino group (NH2)
hydrogen atom
side chain (R) – different for every amino acid
– 20 different amino acids
• Simplest  glycine (side chain is H)
• Alanine  CH3 side chain
• Peptide Bond
– Bond used to connect two amino acids
together through dehydration synthesis
– Forms between the amino group (-NH2) of
one amino acid and the carboxyl group
(-COOH) of another, resulting in the loss of
one water molecule
– Resulting molecule is called a dipeptide
– Long chains of amino acids are called
polypeptides
– All proteins are made of one or more
polypeptides bonded together
• Protein structure (four levels)
– Primary
• Depends on what amino acids are used and how
many
– Secondary
• Amino acid chain can fold into a helix or pleat
– Tertiary
• Considered to be globular or form long chains
– Quaternary
• Combination of long polypeptide chains to form a
protein
• The first protein structure
identified was insulin, a
hormone that controls
blood glucose levels (1954)
• Protein Function
– Make up 15% of your body mass (10,000
different proteins in a single cell!)
– Involved in almost every function of your body
• Structural support
• Cellular transport
• Cell communication
• Speeding up chemical reactions
• Cell growth
– Ex. Muscle, skin, hair, enzymes, hormones,
antibodies
Nucleic Acids
• Composed of
–
–
–
–
–
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
• Function
– Store and transmit genetic information
• Nucleotides
– Basic structural unit
– Contain a phosphate group (PO4), nitrogenous
base and a 5-carbon sugar (ribose or
deoxyribose)
– Nitrogenous base is an
organic base which contains
nitrogen
• Four types:
–Adenine
–Thymine
–Cytosine
–Guanine
– Attached in a sequence along the length of the
molecule (even up to 3 billion pairs!)
• Two forms of nucleic acids in living things
– DNA – Deoxyribonucleic acid
• Hereditary material that is passed on from
generation to generation through reproduction
– RNA – Ribonucleic acid
• Found within the cells nucleus
– Directs and controls the development and
activities of all the cells in an organism
• Structure of DNA
– Resembles the shape of
a ladder
• Two sides (sugarphosphate backbone)
connected to each
other by rungs
(nitrogenous bases)
– Double stranded
– Sugar used is
deoxyribose
– DNA molecule is coiled
into the form of a double
helix
• One human DNA
molecule if stretched
out straight could be 4
cm long!
• Structure of RNA
– Similar in chemical composition to DNA but
consists of only one chain of bases attached
to a sugar-phosphate backbone
– Sugar used is ribose
– The base thymine is replaced by uracil
– RNA is involved in protein synthesis
Main Ideas
• Carbon compounds are the basic building blocks
of living organisms
• Biological macromolecules are formed by joining
small carbon compounds into polymers
• There are four types of biological
macromolecules
• Peptide bonds join amino acids in proteins
• Chains of nucleotides form nucleic acids