Please enable JavaScript.
Coggle requires JavaScript to display documents.
6.2 The structure of DNA and RNA - Coggle Diagram
6.2 The structure of DNA and RNA
DNA and RNA are both made up of nucleotides
Nitrogenous base
Four different bases in DNA
Adenine, Thymine, Guanine, Cytosine
Two types
Purine has two carbon/nitrogen rings
Pyrimidine has one carbon/nitrogen ring
Thymine is replaced by uracil in RNA
Pentose sugar
Sugar with 5 carbons
Two types - ribose and deoxyribose
Deoxyribose has one less oxygen than ribose
Together form the sugar-phosphate backbone
Phosphate group
Gives acidic nature
ATP
Adenine + ribose + 3 phosphate groups
Adenosine = adenine + ribose
Is a nucleotide
Dinucleotides/polynucleotides
Nucleotides can be joined together via condensation reaction
Phosphodiester bonds (ester bonds between phosphate group and sugar)
Features of DNA
5' (5th carbon of sugar) bonded to phosphate
Double helix with strands running in opposite directions (antiparallel)
Bases are held together by hydrogen bonds, which holds both DNA strands together
Complementary base pairing - A-T, G-C
A-T is 2 hydrogen bonds, G-C is 3 hydrogen bonds
Since purines always pair with pyrimidines, DNA is always 3 rings wide
RNA structure
RNA is a single-stranded molecule
However, different types of RNA can form complex structures
mRNA used in transcription
tRNA used in translation
rRNA used for ribosomes