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”