Structure
|
Deoxyribonucleic Acid (DNA) is in the form of a Double Helix with two strands running antiparallel to each other. Each strand consists of alternating phosphate groups and five-carbon sugars. These two phosphate backbones are connected by nitrogenous bases bonded together by hydrogen bonds. |
This ratio is called Chargaff's Principle: A only binds to T and C only binds to G. In all living species, the ratio of Adenine:Thymine and Cytosine:Guanine is 1:1. This discovery gave scientists critical insight into the structure of DNA. |
|
|
DNA is tightly wound into chromosomes. These are formed when the double helix of DNA wraps around histone proteins, creating what resembles "beads on a string". One of these "beads" is the nucleosome. The "string" is packaged into a chord, which is looped around once again to compact it. Finally, the looped chord is packed into the typical chromosome structure. |
Want a Review? Listen to the video on the Right to hear Mr. Roisen review the structure of DNA for you ---> |
|
DNA structure video: http://www.youtube.com/watch?v=8kK2zwjRV0M&list=PL3EED4C1D684D3ADF&index=10&feature=plpp_video\
DNA packaging video: http://www.youtube.com/watch?v=gbSIBhFwQ4s&list=PLD0D5F297744AD515&index=7&feature=plpp_video
Chargaff's Ratio Video: http://www.youtube.com/watch?v=HvJlnujmYcg&list=PLD0D5F297744AD515&index=3&feature=plpp_video
Roisen Review Video: http://www.youtube.com/watch?v=tknYrU98rBk&feature=relmfu
DNA packaging video: http://www.youtube.com/watch?v=gbSIBhFwQ4s&list=PLD0D5F297744AD515&index=7&feature=plpp_video
Chargaff's Ratio Video: http://www.youtube.com/watch?v=HvJlnujmYcg&list=PLD0D5F297744AD515&index=3&feature=plpp_video
Roisen Review Video: http://www.youtube.com/watch?v=tknYrU98rBk&feature=relmfu