1 2 DNA deoxyribose nucleic acid Found in

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2 DNA - deoxyribose nucleic acid -Found in the nucleus of all cells -Controls all of the chemical changes in the cell - The cell’s job is controlled by DNA Ex: Muscle, blood, nerve -The kind of organism produced.

DNA molecule DNA is a very large molecule made up of a long chain of sub-units called nucleotides Each nucleotide is made up of a sugar called deoxyribose a phosphate group -PO 4 and an organic base 3

Ribose & deoxyribose Ribose is a five carbon sugar, like glucose, Deoxyribose is almost the same but lacks one oxygen atom Both molecules may be represented by the symbol 4

5 The bases The most common organic bases are Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

6 Nucleotides The deoxyribose, the phosphate and one of the bases Combine to form a nucleotide PO 4 adenine deoxyribose

Joined nucleotides 7 PO 4 A molecule of DNA is formed by millions of nucleotides joined together in a long chain PO 4 sugar-phosphate backbone + bases

8 -The chains are double stranded. -The sugar phosphate bonds are on the outside. -The chains are held together by chemical bonding of the bases.

2 -stranded DNA PO 4 PO 4 PO 4 PO 4 9

Bonding 1 10 The bases always pair up in the same way Adenine forms a bond with Thymine Adenine Thymine and Cytosine bonds with Guanine Cytosine Guanine