LECTURE: DNA STRUCTURE
LECTURE: DNA STRUCTURE KIRSTIN BROWN
Lecture: DNA STRUCTURE Outline: 1. Nucleotides o DNA vs. RNA
2. Double helix structure 3. Polarity
Nucleotides The building blocks of nucleic acids o The monomers of nucleic acids are called nucleotides
o
Nucleotides have 3 key “ingredients”: ➢ Phosphate ➢ Sugar ➢ Nitrogenous Base
Nucleotides DNA vs. RNA o DNA = deoxyribonucleic acid o RNA = ribonucleic acid
Nucleotides o Nucleotides come in 5 different “flavours” depending their nitrogenous base
Purines
Hint: Purines = smaller name, bigger molecule
Pyrimidines
Nucleotides o Nucleotides come in 5 different “flavours” depending their nitrogenous base
DNA: ATCG RNA: AUCG DNA only
RNA only
Nucleotides o Nucleotides are joined together by a dehydration / condensation reaction o A phosphodiester bond is formed between the 5’ phosphate of one nucleotide and the 3’ hydroxyl of the other.
The double helix o Each strand has a phosphate-sugar backbone, with the nitrogenous base facing inward o Two strands are held together by hydrogen bonds between the nitrogenous bases o The strands are complementary
Polarity The strands in the double helix structure have polarity o Each strand has a 5’ end and a 3’ end o Strands are antiparallel
The double helix Stacking interactions o In addition to hydrogen bonding, stacking interactions occur between bases
The double helix Major and Minor Grooves
Major Groove Minor groove
o The double helix has a major and a minor groove
Lecture: DNA STRUCTURE Outline: 1. Nucleotides o DNA vs. RNA
2. Double helix structure 3. Polarity
Nucleotides The building blocks of nucleic acids o The monomers of nucleic acids are called nucleotides
o
Nucleotides have 3 key “ingredients”: ➢ Phosphate ➢ Sugar ➢ Nitrogenous Base
Nucleotides DNA vs. RNA o DNA = deoxyribonucleic acid o RNA = ribonucleic acid
Nucleotides o Nucleotides come in 5 different “flavours” depending their nitrogenous base
Purines
Hint: Purines = smaller name, bigger molecule
Pyrimidines
Nucleotides o Nucleotides come in 5 different “flavours” depending their nitrogenous base
DNA: ATCG RNA: AUCG DNA only
RNA only
Nucleotides o Nucleotides are joined together by a dehydration / condensation reaction o A phosphodiester bond is formed between the 5’ phosphate of one nucleotide and the 3’ hydroxyl of the other.
The double helix o Each strand has a phosphate-sugar backbone, with the nitrogenous base facing inward o Two strands are held together by hydrogen bonds between the nitrogenous bases o The strands are complementary
Polarity The strands in the double helix structure have polarity o Each strand has a 5’ end and a 3’ end o Strands are antiparallel
The double helix Stacking interactions o In addition to hydrogen bonding, stacking interactions occur between bases
The double helix Major and Minor Grooves
Major Groove Minor groove
o The double helix has a major and a minor groove
