DNA Hybridisation Flashcards
What makes up DNA and RNA?
- Phosphate
- NItrogenous Base
- Pentose Sugar
What is the structure of a Nitrogenous Base?
A ring structure (single or double ring) composed of caron and nitrogen (occasionally oxygen).
What is the strucutre of a Pentose Sugar?
- 5 carbons
- Acyclical structure with oxygen bridge
Which carbon does the nitrogenous base, phosphate group and hydroxyl group join to respectively?
Nitrogenous base joins to carbon 1.
Phosphate group joins to carbon 5.
Hydroxyl group joins to carbon 3.
How is the phosphate group attached to carbon 5?
Via an ester bond
How many hydroxyl group are in RNA?
2
What are the four nucleotides in DNA?
Pyrimidines:
- Cytosine
- Thymine
Purines:
- Guanine
- Adenine
What is the difference in the structure of pyrimidines and purines?
The difference resides in the charged or polar groups providing the specificity of base pairing.
How is the RNA duplex structure formed?
Uracil substitues Thymine and base pairs with Adenine in RNA to form duplex structure.
What are the complementary bases?
Cytosine - Guanine
Thymine - Adenine
How many hydrogen bonds are between C-G and T-A?
3 and 2 respectively
What does the nucleotide chain of DNA form?
It forms a double helix which can take on different combinations.
What is the most common form of DNA?
B-DNA
What forms the backbone of DNA?
From a phosphodiester linkage which connects the 3’ and 5’ prime carbons of the deoxyribose sugar of DNA
What determines the stability of a structure?
The free energy of the molecule and energy minimisation.
What stabilises the structure of DNA?
- Hydrogen bonding of the bases
- Internal arrangement
What other than hydrogen bonding contributes to the stability of DNA?
- Sugar phosphates
- Base stacking
- Van der Waals forces
What is base stacking?
The hydrophobic interactions between the arrangement of bases set above each other internalised to the structure and excludes water from the internal environment of the structure
What gives DNA its overall negative charge?
The bases on the inside forming stacked bases and the negatively charged phosphates are on the outside giving DNA an overall negative charge.
What is the overall negative charge of DNA useful for?
It is used for electrophoresis - in a highly negative environment will migrate to the positive electrode.
What happens when DNA is denatured?
When DNA is denatured, there is conversion of a double stranded molecule to single stranded molecules.
What happens when there is a disruption of the hydrogen bonds?
The hydrogen bonds can be denatured or broken down into its constituent strands.
What structure is formed when DNA is denatured?
- A randomly structured coli
What conditions does DNA need to be under to denature?
- DNA solution is heated
- Induced by strong alkali or urea