Understanding DNA Deoxyribonucleic Acid Double Helix: Two strands twisted around each other like a winding staircase

Rosalind Franklin & Maurice Wilkins

James Watson & Francis Crick

very large linear molecules examples: DNA and RNA sugar phosphate nitrogen base nucleotide store genetic information, help to make proteins

Nucleotides A. Sugar (deoxyribose) B. Phosphate Group C. Nitrogen Bases A B C

Erwin Chargaff AT CG

Rules for Base Pairing: B. Adenine = Thymine (A = T) A. Cytosine Guanine (C G) the lines between the letters are hydrogen bonds

* stores genetic information What is the function of DNA?

C G A A T G Sugar Phosphate Nitrogen Bases

Fun Facts If you wrote down all of the bases in one cell, you would fill a stack of 1,000 phone books with A's, T's, G's and C's

Fun Facts If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.

DNA Replication

DNA Replication Results in two identical DNA strands 1. DNA helicase separates or“unwinds” complementary nucleotide strands. 2. DNA polymerases move along each DNA strand adding nucleotides at the replication fork. 3. Each DNA molecule is composed of one old and one new strand.

Errors DNA polymerases act as proofreaders and make corrections if the wrong nucleotide is added.