L15-16 Nucleotides & Nucleic Acids Flashcards
3 key experiments demonstrating DNA as the genetic material…
Transformation - Griffiths, 1928
Solutions of different cell components -
Avery, McLeod, McCarthy, 1944
Labelled protein and DNA in bacteriophage - Harvey & Chase (1952)
Nuclei acids are comprised of 3 components…
- Heterocyclic base (2 ring purines or single ring pyramidines)
- Sugar ( ribose or deoxyribose )
- Phosphate
Nucleosides contain:
a) base + phosphate
b) base + sugar
c) base + sugar + phosphate
b) base + sugar
Adenine nucleosides names with RNA and DNA sugar…
RNA - adenosine
DNA - deoxyadenosine
Nucleosides are suffixed by -ine
Nucleotides are suffixed by
-ate
Differentiate DNA nucleosides and nucleotides from their RNA counterparts, the prefix….
Deoxy- is added
thymine is exempt from this rule as it only occurs in DNA anyway
Phosphate can be added:
a) only to the 5’ carbon
b) only to the 3’ carbon
c) to either the 3’ or 5’ carbons, but not both
d) to 3’ or 5’ carbons
d) to 3’ or 5’ carbons
5’ is most common, but phosphate binds to 3’ carbon of the next nucleotide when forming polymers
Phosphate has a negative charge. The negatively charged phosphate backbone therefore make the DNA polymer…
Resistant to nucleophilic attack
DNA is…
a) less
b) more
c) equally
… stable in comparison to RNA…
b) more
around 100x more stable
Why is RNA less stable than DNA?
Presence of the hydroxide group can lead to base catalysed hydrolysis of the backbone.
(Base grabs H from hydroxide, electrons attracted to electron poor Phosphorus)
Chargaff’s rule
A and T present in 1:1 ratio, C and G present in 1:1 ratio
Bases are hydrophobic therefore locate…
Inside the helix
The forces between stacked base pairs are…
Van deer Waals forces
The comparative effect of many individually small forces is known as…
Cooperativity
The minor groove of DNA is information…
Poor
