Topic 2.6 - Nucleic acids Flashcards
What is DNA’s structure like ?
A double helix
Who discovered this model ?
James Watson and Francis Crick in 1953 (with Rosalind Franklin’s photograph 51)
What are differences between DNA and RNA ?
DNA = double stranded, genetic info that controls cell functions, nucleus of eukaryotic cells.
RNA = single stranded, generated using DNA as template, allows proteins to be synthesised.
What is the monomer composing DNA and RNA ?
Nucleotides
How many components are nucleotides made of ?
Three = phosphate, sugar and a nitrogenous base.
How is DNA different in prokaryotes and eukaryotes ?
It is confined to the nucleus in eukaryotes (linear) and free or “naked” DNA in prokaryotes (circular).
What are the 4 different nitrogenous bases in DNA ?
Ademine, Thymine, Cytosine and Guanine.
How are these divided ?
Ademine and Guanine are Purines which have a double ringed structure. Thymine and Cytosine are Pyramidines which have a single ringed structure.
How is this structure different in RNA ?
In RNA Thymine is replaced by Uracil.
Describe the complementary base pairing rule.
A pairs with T or U and C pairs with G
Why are there hydrogen bonds linking the bases ?
Because they are weak and therefore ensure easy uncoiling or separation (mitosis or transcription)
What is special about DNA strands ?
They are antiparallel which means that they run in opposite directions, one runs from 5’ to 3’ and the other one from 3’ to 5’.
