Nucleic Acids Biotechnology
DNA Deoxyribonucleic acid Forms the Genetic Code
1953 The work of four people identify the structure of DNA. This knowledge opens the floodgates of scientific discovery that have begun to shape the modern world.
Nature publishes James Watson's and Francis Crick's manuscript describing the double helical structure of DNA, which marks the beginning of the modern era of genetics. 1953
James Watson Francis Crick Maurice Wilkins The Nobel Prize in Physiology or Medicine 1962
2 Categories of Cells Eukaryotic Plant Animal Prokaryotic
The two types of cells have different arrangements and amounts of DNA:
Bacterial DNA Single circular chromosome. 0.5 to 5 x 10 6 bp (~1.5 mm in a 1~2 µm cell) Some small plasmids.
Eukaryotic DNA There is so much it is compacted into Chromatin. Then packaged into Chromosomes.
DNA Packaging in Eukaryotic Cells: Chromosome Chromatin DNA
DNA Structure A molecule of DNA is made up of millions of tiny subunits called Nucleotides. Each nucleotide consists of: 1. Phosphate group 2. Pentose sugar 3. Nitrogenous base
Lets look at each of the three pieces:
Phosphate Group Gives DNA its NEGATIVE charge.
Deoxyribose: Pentose Sugar Carbons are numbered from 1 to 5 clockwise around the molecule.
Nucleotides Four different Nitrogen Bases. Placed into 2 categories: Purines (Two Ringed): Adenine Guanine Pyramidines (One Ringed): Thymine Cytosine
DNA nucleotides are linked together by covalent bonds to form a single strand. Two nucleotides can be linked together by a covalent bond between the Deoxyribose of one molecule and the Phosphate of the next molecule. More nucleotides are added in the same manner until they form a chain of molecules.
DNA consists of two nucleotide chains that are arranged into a ladder-like structure called a Double Helix.
DNA double helix is formed using complementary base pairing & hydrogen bonds. Two strands of these nucleotide chains are bonded together into a single molecule that has a particular shape, called a DOUBLE HELIX. Hydrogen bonds link these two strands together, forming between the bases of each pair of nucleotides.
The 4 Bases in DNA.»Adnine (A)»Thymine (T)»Cytosine (C)»Guanine (G)
Nucleotides A Adenine T Thymine C Cytosine G Guanine
Nucleotides Each base will only bond with one other specific base. Adenine (A) Thymine (T) Form a base pair. Cytosine (C) Guanine (G) Form a base pair.
Complimentary Base Pairs Adenine will ONLY forms hydrogen bonds with Thymine. Cytosine ONLY forms hydrogen bonds with Guanine.
Purines: 2 of the bases are made of 2 rings. These are the purines. Adenine & Guanine.
Pyramidines Composed of one ring. Cytosine & Thymine.
Nitrogen Bases
Bonding: The Purine Adenine will ONLY bond with the Pyramidine Thyamine. Each of these require 2 hydrogen bonds to hold them together.
Bonding (2): The Purine Guanine wil ONLY bond with the pyramidine Cytosine because they both require 3 hydrogen bonds to hold them together.
Bonding
A C T C A G T G A G T C T A
DNA Structure Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.
Hydrogen Bonds H H H H O O H C C C C N N C Thymine H N H H N C C C C N N H N C Adenine H O N H C C C N N C Cytosine H H H N C C C C N N H N C Guanine N H O H
Nucleotides The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the rungs. There are four types of nitrogenous bases.
The 2 strands are Antiparallel
DNA Structure Key Ideas If a gene is a section of DNA that codes for a specific 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 unique proteins and combination of proteins that give us a unique phenotype.
Gene DNA Protein Trait