Deoxyribonucleic Acid DNA Deoxyribonucleic Acid Watson and Crick

How does DNA function? DNA contains all the genetic information for our cells (and ultimately for our body). The genes that are made up of DNA tell the cells which proteins to make. Those proteins determine how each cells functions. So DNA ultimately controls all cell functions. ** Holt Biology Interactive Tutor 6-1

What is DNA made from? The monomers of DNA are called nucleotides: 1. nitrogenous base (adenine, thymine, guanine, cytosine) 2. pentose sugar (5 carbon sugar called deoxyribose) 3. phosphate group The nucleotides are assembled (joined) during a dehydration synthesis or condensation reaction.

Nucleotide structure:

Four Nitrogenous Bases (DNA) PURINES PYRIMIDINES A = adenine T = thymine G = guanine C = cytosine *Double rings of carbon * Single rings of carbon and nitrogen. and nitrogen.

DNA is shaped like a double helix. The double helix model indicates that DNA is composed (made) of two nucleotide chains that wrap around each other to form a double spiral...like a spiral staircase or twisted ladder.

How do we know about DNA’s shape? The double helix is the model proposed by scientists James Watson and Francis Crick in 1953. They received a Nobel Prize in 1962 for their discovery. Watson and Crick’s model was supported by evidence from other scientists like Rosalind Franklin and Maurice Wilkins who studied X-ray crystallography (photographs) of DNA.

What is the complimentary base pairing rule? Nucleotides in the chain (backbone) are connected covalent phosphodiester bonds between the phosphate group of one nucleotide and sugar group of an adjoining nucleotide. This occurs during a dehydration synthesis or condensation reaction.

Complimentary Base Pairing Rule adenine - thymine (2 hydrogen bonds) cytosine – guanine (3 hydrogen bonds) * The sequence in one chain is the exact compliment of the other chain.

DNA code: T A C T A G C A A A C T Complimentary sequence would be..? **Holt Biology Interactive Tutor 6-2 Now you try it... DNA code: T A C T A G C A A A C T Complimentary sequence would be..?