DNA Mrs. Harlin

3.1.1 Explain the double-stranded, complementary nature of DNA as related to its function in the cell.

DNA Structure The structure of DNA is a double helix or “twisted ladder.” The subunit of DNA is the nucleotide. The nucleotide consists of three parts: Phosphate Group Sugar (deoxyribose) Nitrogenous base (either A, T, C, or G)

DNA Structure The 2 strands are connected by weak bonds called hydrogen bonds. http://publications.nigms.nih.gov/thenewgenetics/images/ch1_nucleotide.jpg

DNA Replication The process of copying DNA. Occurs in the nucleus of a cell during the S phase of interphase before mitosis. Allows daughter cells to have an exact copy of parental DNA. Cells respond to their environments by producing different types and amounts of protein.

Complementary Base Pairing If one side of the DNA strand reads: TAC GCA GTT The other side will read: ATG CGT CAA

The rule is: The nitrogenous base A (Adenine) always pairs with T (Thymine). The nitrogenous base C (cytosine) always pairs with G (guanine).

The Genetic Code The sequence of nucleotides in DNA codes for proteins, which is central key to cell function and life.