DNA Notes

DNA Notes
DNA—a chemical that contains information that an organism needs to grow and function; sometimes called the Blueprint of life.
1. Watson and Crick made an accurate model of DNA in 1953.
2. The structure of DNA is similar to a twisted ladder.
a. The sides of the ladder are made up of sugar-phosphate molecules-(the sugar being dioxyribose)
b. The rungs of the ladder are made up of nitrogen bases-there are 4 nitrogen bases-adenine, guanine, cytosine, thymine–Adenine pairs to Thymine Guanine pairs to Cytosine
3. Before a cell divides, its DNA duplicates itself by unwinding and separating its sides, then forming new sides

Genes—sections of DNA on a chromosome
1. Contain instructions for making specific proteins
2. RNA carries the codes for making proteins from the nucleus to the ribosomes in the cytoplasm.-RNA is similar to DNa except that the sugar that makes DNA is Ribose and the 4 nitrogen bases are uracil, cytocine, adenine, and guanine and it is a ladder with only one side. THerE are 3 types of RNA
a. Messenger RNA carries the code that directs the order in which the amino acids bond.
b. Ribosomal RNA makes up ribosomes, where proteins are built.
c. Transfer RNA brings amino acids to the ribosomes to build the protein.
3. Cells use only the genes that direct the making of proteins needed by that cell.
C. Mutations—any permanent change in the DNA sequence of a cell’s gene or chromosome
1. Can be caused by outside factors like X rays, sunlight, and some chemicals
2. A change in a gene or chromosome can change the traits of an organism.