DNA notes DNA = Deoxyribonucleic Acid The primary function of DNA is to store and transmit genetic data.

Fun Facts! If the DNA in a single human cell were stretched out and laid end-to-end, it would measure approximately 6.5 feet (2 meters). The average human body contains 10 to 20 billion miles (16 to 32 billion kilometers) of DNA distributed among trillions of cells.

History Rosalind Franklin took the first picture of DNA using an X-ray. James Watson and Francis Crick followed up on her work and came up with the DNA structure, the double helix (twisted ladder). Watson and Crick were awarded the 1962 Nobel Prize for their work. Franklin may have won it too, but she died earlier.

Structure of DNA The backbone (sides of ladder) of DNA is made up of sugar and phosphate molecules. Each rungs (step) is made up of 2 nitrogen bases. There are 4 types of nitrogen bases: Adenine Thymine Cytosine Guanine

The 2 strands of DNA are complimentary to each other

Nucleotides Adenine and Guanine are purines Thymine and Cytosine are pyrimidines A pairs with T C pairs with G

1. Replication DNA makes copies of itself before Mitosis and Meiosis, in S-Phase. (remember the cell cycle!!) A protein called DNA polymerase goes down each of the DNA strands and makes complimentary copies in the nucleus.

Replication Replication is usually very accurate, but mistakes can happen- deletions or duplications- but there is another protein, a “spell checker”, that catches most of the mistakes made. Mistakes that are not caught can lead to cancer and genetic disorders.

2. Transcription mRNA is made using a single strand of DNA as a template. It works the same way as replication, but only a single strand of mRNA is made. A protein called RNA polymerase moves down the DNA strand and a complimentary strand of mRNA is created.

Transcription Happens in the nucleus. In mRNA, a nucleotide called Uracil (U) pairs with Adenine instead of Thymine.

3. Translation Happens outside the nucleus (in ribosomes) Proteins are made using the mRNA as a template. Ribosomes attach to a strand of mRNA and read the mRNA. For each sequence of 3 nucleotide bases (called a codon) a certain amino acid is matched.

Translation

Translation tRNAs have anticodons that match the codons on mRNA. When a tRNA finds a matching codon for its anticodon, it attaches the amino acid it carries for that specific codon. Amino acids get hooked onto each other and form a polypeptide chain, which eventually forms a protein.