Transcript Week 9

Organic
Chemistry
and the
Genetic
Code
 Organic chemistry: Compounds in which
Carbon is the principal element.
 Recall carbon as the leading Group IV element in
the Periodic Table, with 4 valence electrons.
 The study of compounds that do not contain
carbon as a central element is called:
Inorganic Chemistry.
The majority of known compounds are organic.
Several million are known .
Thousands more are created each year.
Fossil fuels, oil & gasoline, all food & beverages,
plant & animal substances, synthetic and natural
rubbers, polymers, plastics, and pharmaceuticals.
 Hydrocarbons
Alkanes
 Single C-C Bonds
Alkenes
 Double C=C Bonds
Alkynes
 Triple C=C Bonds
Ethylene ( Ethene )
Acetylene ( Ethyne )
Organic compounds may contain other
elements or groups besides C and H.
Oxygen, nitrogen, the halogens
( fluorine, chlorine, bromine, iodine )
phosphorus or sulfur.
NO2 (nitrate) group
OH (hydroxide) group
PO4 (phosphate) group
 Molecular structures: Dashes between
represent chemical bonds.
1 bond = 2 electrons
 Octet rule: Carbon atom has 4 dashes
around it ( 2 x 4 = 8 electrons ).
Double or triple bonds:
Less hydrogen H atoms attached
 Unsaturated
atoms
Simple molecules can combine with each other to
form long chains of molecules with identical
repeating units or groups.
 Polymers (“many units”).
Individual segments  monomers.
E.G. Ethylene is heated under pressure with a
catalyst to form polyethylene, the most popular
industrial plastic in the world.
E.G. Plastic bags, shampoo & beverage bottles, toys,
CD covers, bullet-proof vests.
.
1 hydroxide OH group per molecule is called an
alcohol. E.G. Methanol, ethanol, and isopropyl
alcohol all have 1 OH group attached to them.

2 hydroxyl OH groups per molecule is called a
glycol. E.G. Ethylene glycol is the major component
of antifreeze.

3 hydroxyl OH groups per molecule is called a
glycerol. Glycerol is a building block of fat
molecules and a by-product in the manufacture of
soap. Used in toothpastes, lotions, and candy to
retain moisture / softness.

 Carbohydrates are carbon, hydrogen and
oxygen ( C-H-O ) compounds.
 Simple sugars ( or monosaccharides )
provide fuel for living cells.
 Glucose (C6H12O6)
 Provides energy and shape to certain cells.
 Essential role in molecular genetics.
 Polypeptides: Enzymes & catalysts. Increase the
rate of chemical reactions in living things.
 Hemoglobin: Serves as an oxygen carrier.
 Collagen: Provides shape and support.
Responsible for muscle movement.
 Hormones: Chemical messengers secreted by
endocrine glands to regulate the body.
 Antibodies: Globular proteins made up by the
body in response to the presence of a foreign
or harmful molecule called an antigen.
Proteins are polymers made up of
monomers known as amino acids:
Amino group ( NH2 )
Carboxylic Acid group ( COOH )
Segment of DNA that is able to:
 Replicate itself
 Mutate (or change) itself
 Store information about itself
 Synthesize new structural proteins essential
to the operation of the cell or organism.
 Physical Traits
~ Functions ~
 Replication: Ability to reproduce itself.
 Transcription: Ability to supervise the
manufacture of RNA.
 Translation: Production of new protein
molecules by RNA.
~~~~~~~~~~~~~~~~~~~~~~~~
DNA is the genetic material determining
which proteins will be manufactured.
 Nucleic acids (DNA / RNA) composed of
fundamental monomers
 Nucleotide monomer is composed of:
1) Sugar molecule
( 5-member carbon ring skeleton )
2) Phosphate ( PO4 group )
3) Base or Amino acid
( Hexagonal 6-member C-N ring skeleton)
Adenine: A
Guanine: G
Cytosine: C
Uracil: U
Thymine: T
~~~~~~~~~~~~~~~~~
DNA has bases A, T, G, C
RNA has bases A, U, G, C
 DNA is actually a double molecule.
 Composed of two strands to form a
ladder- like structure (double helix)
thousands of nucleotide bases long.
 Strands are attached between their bases
according to the base pair rule:
A–T
G–C
 The 4 letters in the nucleic acid “alphabet”
yield 64 possible unique 3-letter words.
 This is the basis of the genetic code
for all living organisms.
 If these bases are read in groups of three,
they make sense to us ( CAT, TAG, ACT ).
 To make sense out of such a code,
it is necessary to read in only one direction
(as in many languages).
DNA replication is stunningly accurate.
1 error made for every 2 billion nucleotides.
Human cell: 46 chromosomes
~ 3 billion base pairs
~ 1.5 errors per cell
Because this rate of error is so small,
DNA replication is considered to be
“Error – free”