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http://publications.nigms.nih.gov/thenewgenetics/chapter1.html
DNA StructureDNA consists of two molecules that are
arranged into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of tiny subunits called Nucleotides.
Each nucleotide consists of:1. Phosphate group2. Pentose sugar3. Nitrogenous base
http://i-biology.net/ahl/07-nucleic-acids-and-proteins/
Nucleotides
Phosphate
Pentose
Sugar
Nitrogenous
Base
NucleotidesThe phosphate and sugar form the
backbone of the DNA molecule, whereas the bases form the “rungs”.
There are four types of nitrogenous bases.
AnalogiesStrengths of
Ladder AnalogyWeaknesses ofLadder Analogy
• double-helix shape is well represented
• location of sugar-phosphate backbone is accurate
• location of nucleotides is accurate
• individual nucleotides (A, T, C, G) are not represented
• individual sugars and phosphates are not shown
• base pairing (A-T, C-G) is not represented
Nucleotides
A
Adenine
T
Thymine
G
Guanine
C
Cytosine
NucleotidesEach base will only bond with one
other specific base.
Adenine (A)Thymine (T)
Cytosine (C)Guanine (G)
Form a base pair.
Form a base pair.
DNA StructureBecause of this
complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.
http://1.bp.blogspot.com/_gWQaU40PH24/S7J-tYkvibI/AAAAAAAAGas/-_raVWK4zx4/s1600/dna%5B1%5D.gif
Complementary base pairingPurines Pyramidines
Adenine ThymineAdenine Uracil
Guanine Cytosine
G
G
A
T
T
A
A
C
T
G
C
A
T
C
DNA StructureTo crack the genetic code found in
DNA we need to look at the sequence of bases.
The bases are arranged in triplets called codons.
A G G - C T C - A A G - T C C - T A GT C C - G A G - T T C - A G G - A T C
DNA StructureA gene is a section of DNA that codes
for a protein.
Each unique gene has a unique sequence of bases.
This unique sequence of bases will code for the production of a unique protein.
It is these proteins and combination of proteins that give us a unique phenotype.
Protein
DNA
Gene
Trait
Nature of the Genetic MaterialProperty 1 - it must contain, in a
stable form, information encoding the organism’s structure, function, development and reproduction
Property 2 - it must replicate accurately so progeny cells have the same genetic makeup
Property 3 - it must be capable of some variation (mutation) to permit evolution
Your TaskDraw a flow chart to
show how to get from:
http://207.207.4.198/pub/flash/24/menu.swfNova-Cracking the Code of LifeThe Structure of DNA