DNA controls the activities of cells and carries genetic information. It is found in the nucleus of cells. In 1953, James Watson and Francis Crick discovered that DNA has a double helix structure with alternating sugar and phosphate molecules forming the backbone and four nitrogen bases - adenine, guanine, cytosine, and thymine - bonding between the strands in a specific pattern with adenine bonding to thymine and guanine bonding to cytosine. DNA is made up of small repeating units called nucleotides, each containing a sugar, phosphate, and one of the four nitrogen bases.
2. What is DNA? Nucleic acid – a compound composed of a 5-carbon sugar, a nitrogen base, and a phosphate. Deoxyribonucleic acid – DNA – controls the cells activities, carries genetic information. It is found in the nucleus of the cell.
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4. Who discovered DNA? DNA was discovered in the late 1940’s, but the structure was not discovered until 1953 . Two scientists named James Watson and Francis Crick came up with a model of the structure of DNA.
5. What does Watson and Crick’s DNA model look like? The shape looks like a twisted ladder – double helix . Each side is made up of alternating sugar and phosphate molecules. The sugar in DNA is called deoxyribose. Attached to each sugar is a nitrogen base . To make the ladder complete, each base is joined by a weak hydrogen bond to a base on the other side.
11. How are these parts put together? DNA is built up in small units. Each unit is made up of a sugar , a phosphate , and a nitrogen base . This small unit is called a nucleotide .