DNA The Molecule of Life

The Basics of DNA DNA = DeoxyriboNucleic Acid Found in the Nucleus of cells Made up of nucleotides containing 3 parts: 5 Carbon Sugar = Deoxyribose Phosphate Group Nitrogen Base

The Bases There are 4 different Nitrogen Bases for DNA They are divided into 2 groups based on their chemical structure Purines = Adenine & Guanine Pyrimidines = Cytosine and Thymine

DNA Structure We refer to the structure of DNA as a Double Helix (spiral) It resembles a twisted ladder Its sides are formed from long chains of sugar & phosphate The ‘rungs’ are the pairs of Nitrogen bases

Just some interesting facts All 46 chromosomes in humans contain more than 5 Billion nucleotides! The smallest known virus contains about 5,000 nucleotides The structural and chemical make-up of DNA is the same in all organisms! Only the sequence of the nucleotides varies

How the structure forms… A purine and a pyrimidine must pair with each other make a rung that is the right width If 2 purines were together, it would be too wide If 2 pyrimidines were together, it would not be wide enough Weak Hydrogen bonds hold the bases together They are able to break easily, allowing the DNA to open like a zipper

Replication The process by which DNA copies itself is called replication The H-bonds connecting the bases break in several places and the molecule separates down the middle As the molecule splits into separate strands, special enzymes cause the proper nucleotides to pair with complementary nucleotides on each strand

Replication continued… Other enzymes then link the nucleotides into one long strand Each original strand serves as a template or pattern, for the creation of the new strand Every T (Thymine) nucleotide pairs with a nucleotide containing an A (Adenine) Every G (Guanine) nucleotide pairs with a nucleotide containing a C (Cytosine)

Final thoughts of Replication Each completed DNA molecule now contains one old and one new strand The entire process is powered by energy from ATP and the action of enzymes

Just a Preview….. Coming soon to a classroom near you! RNA….the OTHER nucleic acid

Any Questions?? That’s all folks!