Change: Genetic Code is Discovered in 1953

	The genetic code is shared by all organisms
In 1953 Watson and Crick's Discovery of the Double Helix
The four nucleotides found in DNA differ only in their nitrogenous bases.
	Thymine (T) and Cytosine (C) are single-ring structures. Adenme (A) and Guanme (G) are larger, double-ring structures. RNA has the nitrogenous base Uracil (U) instead of thymine. RNA also contains a slightly different sugar than DNA (ribose instead of deoxyribose). Other than that, RNA and DNA polynucleotides have the same chemical structure.
The discovery of ribozymes suggests that the original genetic material was RNA.	In 1981 it was found that RNA can excise 400 nucleotides in the absence of any protein. Called ribozymes, these RNA molecules can cut out parts of their own sequences, connect some RNA molecules together, replicate others. Self-replicating ribozymes probably first arose between 3.5 billion and 4 billion years ago. Early life was an RNA world, with RNA molecules serving both as carriers of genetic information and as catalysts that drove the chemical reactions needed to sustain and perpetuate life. These catalytic RNA’s may have acquired the ability to synthesize protein-based enzymes, which are more efficient catalysts; with enzymes taking over more and more of the catalytic functions, DNA took on the role of information storage and transfer, eventually replacing RNA as the primary carrier of genetic
Progress on genetic enlightenment
Prokaryotic first life 3.5 bya Followed by membrane housed Eukaryotic cells 1.7 bya	small Prokaryotic and larger Eukaryotic cells Microscopes enabled search
Phosphorus yellow is essential to forming DNA’s back bone Our Sun is too small a star to manufacture phosphorus
Genetic information is transferred from DNA to RNA to protein.
Most DNA is contained in the Nucleus	Synthesis of mRNA to cytoplasm to synthesis of Protein
The DNA Code
Close-up view of transcription molecule of mRNA
The gene is the fundamental unit of heredity ; genes are located on chromosomes
non-sex cell mitosis,
sex cell with mitosis and meiosis
Male and female gametes (sperm and egg) differ in size The X & Y chromosomes in humans differ in size and genetic content.
Genomic characteristics of humans
Universal tree of life can be constructed from 165 rRNA sequences Humans top right