DNA and RNA Flashcards
What are the Purines
Adenine and Guanine
2 Rings
Pur Ag Rings
What are the pyrimidines?
Cytosine, Uracil, Thymine
1 Ring
CUT py pie is a ring
Nucleotide vs Nucleoside
Nucleotide has a phosphate on the 5’ OH of the Sugar
Nucleoside is a Sugar and N-Base only
What is the five carbon ring of RNA and DNA called?
Furanose ring
What is the difference between the furanose ring of RNA vs DNA?
The furanose ring of RNA has an OH on the 2’ Carbon. In DNA there is an H at the 2’ Carbon
What pairs together with DNA?
Purine always pairs with a pyrimidine
A-T
A-U
G-C
How many bonds form between the bases of A-T, A-U, G-C?
A-T, A-U = 2 hydrogen bonds
G-C = 3 hydrogen bonds
How are DNA monomers linked?
They are linked by phosphodiester bonds of the 3’ and 5’ carbons of the furanose rings. By convention, they are usually written in a 5’ to 3’ direction.
What increases the Melting Point of DNA?
The more G-C bonds there are, the higher the MP due to more hydrogen bonds. 3 hydrogen bonds vs 2 with A-T
As DNA length increases what happens to the Melting Point
The melting point also increases due to more hydrogen bonds between N-Bases
As NaCl concentration increases what happens to the melting point of DNA?
DNA melting point increases.
DNA is highly negatively charged and the phosphodiester linkages normally repel each other, weakening the interaction between the strands. NA+ will actually for cation shields around the linkages that then strengthen the bonds of the helix.
What happens to renaturation of single strands to double strands as DNA concentration of single strands increases?
The renaturation of single strands to double strands increase as well.
Like any chemical reaction, the molecules need to be oriented in the right direction for an interaction to occur. When you increase the concentration of reactans, in this case DNA, you also increase the likelihood that the reactants will meet in the proper orientation. The rate therefore increases.
What happens to the Tm (melting point) of DNA as Urea is added to the solution?
Melting point decreases as Urea is added to the solution.
Urea is a polar molecule that is capable of being a hydrogen bond donor and acceptor:
H2N-CO-NH2
This disrupts the hydrogen bonds of DNA and weakens the double helix.
If DNA has 20% cytosine, what percentage of Adenine does it have?
It will have 30% adenine.
20% cytosine means 20% guanine, leaving 60% for adenine and thymine combined.
What is the water solubility of the phosphate groups, the ribosyl group, and the nitrogen bases?
Phosphate is negatively charged, so it will be hydrophilic. The hydrogen dipoles will surround the charged parts of the phosphate group
The Ribosyl group is polar with it’s oxygen right before the 1’ Carbon. It will be hydrophilic as well.
The N base is mostly hydrophobic so it groups to the middle.