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 atoms 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

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.

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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 (C 6 H12O 6 ) 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”