Nucleic Acids Flashcards
What kind of sugar is ribose?
Pentose ( 5-carbon)
Deoxyribose has its hydroxyl group replaced on which carbon?
2’
Which nitrogenous bases are purines?
Adenine and Guanine
Which nitrogenous bases are pyrimidines?
Thymine, Uracil and Cytosine
Nitrogenous bases are attached to sugars on which carbon
1’
Which type of bases are single ring structures?
Pyrimidines
Which type of bases are double ring structures?
Purines
Why type of bonding links bases to sugars?
Glycosidic
On which N atom are pyrimidines linked to sugars
1
On which N atom are purines linked to sugars
9
What kind of bond connects nucleotides?
Phosphodiester linkage
On what C atom does a sugar have its triphosphate group attached?
5’
Which groups are cleaved off when nucleotides polymerize?
The beta and gamma phosphate groups of one nucleotide, and the hydroxyl group on the 3’ carbon of the other
What is the 5’ end?
There is a triphosphate group on the 5’ carbon of one nucleotide which hasn’t participated in a phosphodiester linkage
What is the 3’ end?
The hydroxyl group on the 3’ carbon of a nucleotide at one end of a polynucleotide chain
A chromosome is made of very densely packed entrails known as _
Chromatin
Chromatin is a large amount of DNA wrapped around proteins called _
Histones
Which proteins play a crucial role in packaging DNA very tightly
Histones
What is a nuceloside?
A sugar group with a nitrogenous base
The hydroxyl group on the 3’ carbon of the sugar tends to interact with phosphate groups because it is a _
Nucleophile
The linkage of around 10 nucleotides is a _
Oligonucelotide
Give two names for the process of putting together two strands of DNA in a double helix structure
Hybridisation and Annealing
Why do bases interact through stacking?
They are aromatic compounds and interact through pi stacking
What does it mean to say that DNA is right handed?
It means that clockwise rotation moves the strand away from the observer
DNA strands run in opposite directions, they are _
Antiparallel
What does it mean to say that DNA is not regular in its shape?
There are deeper and shallower grooves, known as major and minor respectively
At how many sites to G and C bases form hydrogen bonds?
3
At how many sites to A and T bases form hydrogen bonds?
2
What is the typical diameter for a b-form helix?
2.37nm
What is the typical pitch of a b-form helix? What does that mean?
3.47nm, 10 base pairs constitute one complete turn in the structure
What two phenomena can affect the molecular conformation of DNA/nucleotides?
Sugar pucker, rotation around the beta-N-glycosidic bond
Which two conformations can the sugar adopt?
C2’-endo and C3’-endo
Dimensions of fibres containing DNA change when _
Exposed to different humidity
