DNA

Where it is at: Chromosomes make up DNA DNA= deoxyribonucleic acid DNA is made up of segments called genes Each gene codes for a protein (on and off switch) that makes up what we look like.

A Brief Look Back In 1869, Swiss biochemist Johann Miescher discovers a nitrogen and phosphorous material in cell nuclei that he calls nuclein but which is now known as genetic material DNA. 1953, American biologist James D Watson and English geneticist Francis Crick develop a double helix model for the structure of deoxyribonucleic acid (DNA) By the 1980’s scientists could extract DNA, determine a baby’s parents, and match criminals to the scene of the crime.

A Brief Look Back At this time a mutation (any change in a gene or chromosomes) was associated only with disease. We now know otherwise. Starting in 1990. the Human Genome Project, headed by Wastosn was designed to map out the locations of each human gene and determine their specific codes. A rough draft was released in 2000, five years ahead of schedule. In 2003, this project was completed in 99.9% accuracy.

What we know now: Each cell in the body (except eggs & sperm) has 6 feet of DNA coiled inside of it. Only 5% of each 6 feet of DNA are genes that code for protein. Still, humans have about 100,00 genes that make up each person’s identity.

The make up of DNA: The DNA Double Helix is like a twisted ladder. In order to read the code we need to untwist the double helix. The sides of DNA are made up of alternating phosphates and sugars. Holding the two sides of the DNA structure together are the nitrogen bases.

There are 4 Types Adenine Thymine Cytosine Guanine

Nitrogen Bases The four bases make up each code (for a gene). In order to keep the steps between sugars the same size the bases can only be paired with certain bases. A AND T G AND C T AND A C AND G

The makeup of DNA One side of the DNA is considered the code, the other the compliment. The code is made up of the four bases, grouped into threes as codons: All gene segments start with a start codon = ATG and end with a stop codon= TAA, TGA, or TAG A gene code can be one to thousands of codons long. The body knows where one gene stops and another starts by reading the code following the stop and start codons.

Mutation A mutations is a permeant change in a gene or chromosome of a cell: it may be beneficial, harmful or have little/no effect on an organisms. Mutations can occur as a result of deletion, insertion or substitution of a nitrogen base in the DNA sequence.