From gene to protein -slides

The Molecular Basis of Life

in One hundred thirty years have gone from the extraction of DNA to the human Genome project

-→ years ago “nuclein” DNA was concluded by Meischer

Eighty years later - DNA confirmed as the Hereditary info of all life - concluded by Watson and Crick

1990 ; human Genome Project started ~ eleven years later DNA sequenced

From Human genome project ~ 20,000 protein encoding genes in the human genome project

()(Originally predicted 100,000)

What is the purpose of the “noncoding DNA”?

sequence of nucleotides = genes = polypeptide

1908 Garrod

hypothesized, hereditary material codes for enzymes

1941 Beadle and Tatum

Experimented Evidence → one gene codes for one enzyme

1959 Ingram

Sickle cell anemia due to single amino acid substitution in the hemoglobin protein

Thus sequence of nucleotides provides the info. the specifies the order of amino acids in a protein

sequence of nucleotide = gene

One Gene → one Polypeptide

four nucleotides for 20 amino acids

Problem:

1 nucleotide coding for 1 amino acid -→ four amino acid

two nucleotide coding for 1 amino acid -→ sixteen

three nucleotide coding for 1 amino acid -→ sixty-four

→ triplets

Why must DNA must remain in the nucleus? - In cytoplasm it can be changed or damaged, leading to cell death, or possibly a dead organism

Since DNA must remain in the nucleus, what are problems that occur? - 1. proteins manufactured on ribosome in cytoplasm 2. only 2 copies of DNA in a cell (need large number of proteins)