What is recombinant DNA ?

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DNA structure

#1. DNA Structure (an overview)

• DNA has three main components

– 1. deoxyribose (a pentose sugar)

– 2. base (there are four different ones)

– 3. phosphate

#2. The Bases

 They are divided into two groups

 Pyrimidines and purines

 Pyrimidines (made of one 6 member ring)

 Thymine

 Cytosine

 Purines (made of a 6 member ring, fused to a 5 member ring)

Adenine

Guanine

 The rings are not only made of carbon (specific formulas and structures are not required for IB)

#3. Nucleotide Structure

• Nucleotides are formed by the condensation of a pentose sugar, phosphate and one of the

4 bases

• The following illustration represents one nucleotide

• Nucleotides are linked together by covalent bonds called phosphodiester linkage

#3. Nucleotide Structure

#4. DNA Double Helix and Hydrogen Bonding

• Made of two strands of nucleotides that are joined together by hydrogen bonding

• Hydrogen bonding occurs as a result of complimentary base pairing

– Adenine and thymine pair up

– Cytosine and guanine pair up

– Each pair is connected through hydrogen bonding

– Hydrogen bonding always occurs between one pyrimidine and one purine

• Complimentary base pairing of pyrimidines and purines

#4. DNA Double Helix and Hydrogen Bonding

#4. DNA Double Helix and Hydrogen Bonding

#1. DNA Structure (an overview)

• DNA has three main components

– 1. deoxyribose (a pentose sugar)

– 2. base (there are four different ones)

– 3. phosphate

#2. The Bases

 They are divided into two groups

 Pyrimidines and purines

 Pyrimidines (made of one 6 member ring)

 Thymine

 Cytosine

 Purines (made of a 6 member ring, fused to a 5 member ring)

Adenine

Guanine

 The rings are not only made of carbon (specific formulas and structures are not required for IB)

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