Nucleic acids and nucleotide metabolism Flashcards
what are nucleotides
Basic monomeric unit comprising nucleic acids
what makes up nucleotides
heterocyclic nitrogenous base, sugar and
phosphate(s)
what is the sugar in DNA and RNA
ribose and 2-deoxyribose
what are the purines
A + G
what are the pyrimidines
T + C
Why is uracil only found in RNA and not DNA?
- Thymine has a more stabilised structure than Uracil
- RNA is relatively unstable, whereas DNA is used to store long-term genetic information
what do purines and pyrimidines bind too
Purines only bind to pyrimidines and vice versa! Then cannot bind to their own class type!, even more so, they can only bind to a specific opposite. This is termed base pairing.
what are easily separated during DNA replication
hydrogen bonds
what is the link between 2 sugar residues
phosphodiester
what is the link between 2 sugar residues
phosphodiester
what charge is every residue or polymerised monomeric unit in DNA or RNA molecule
negatively charged at physiological pH
what did Watson and crick discover
Two strand helix stabilised by hydrogen bonding between bases on opposite strands
anti-parallel double helix with 10 base pairs per turn
what are Polynucleotides 2 very important features
- sense or directionality- (phosphodiester linkage between monomers is between 3’ C of one monomer and 5’ C of the next). One end will have an unreacted phosphate and the other end an unreacted hydroxyl end
- individuality- this is the primary structure (amino acids and peptides) nucleotide sequence determined by composition of bases will be unique
what is vital for DNA helix stability
base pair bonds
what is char gaffs rule
Adenine can only pair with Thymine, and Guanine can only pair with Cytosine
AT (double H bond)
G C (triple H bond) DNA with lots of G & Cs has a higher thermal stability!
