Nucleic Acids Flashcards
What are all the nucleotides
C- Cytosine T- Thymine A- Adenine G- Guanine U- Uracil
What are the 3 components that nucleotides composed of
Nitrogenous base
Pyrimidine - C, T, U
Purine- G, A
Pentose sugar
Deoxyribose in DNA
Ribose in RNA
Phosphate group
What is the name of the bond that binds the ribose sugar and nucleotide base
Glycosidic bond
What is the name of a adenosine
Nuceloside
sugar and a base
Which base pair is the strongest
AT
What electrostatic forces are found in the DNA double helix
van der Waals forces
What is found at the end of the nucleotide polynucleotide chain
3’
How is the 3’ -5’ phosphodiester bond formed
The alpha phosphate of the new nucleotide reacts with the 3’ OH group
What direction does the chain grow
5’ - 3’
What stage of the cycle does DNA replication occur
S phase of interphase
What is DNA replication vital for
Growth
repair
repdroduction
Describe the DNA replication mechanisms
1- Replication fork mechanism
Double stranded DNA unzipped via DNA helices and forms a Y Shaped replication fork which used as a template for replication to occur.
- RNA primer binding
primer binds to the 3’ end of strand acting as the started point - Elongation
DNA polymerase alpha binds to the strand at the site of the primer and adds new complentart base pairs to the strand during replication - Termination
RNA primers are degraded and filled by RNAse H and DNA pol d
What are primers generated by
DNA primase
Why is the replication fork bi directional
One strand oriented 3’ to 5’ direction (=leading strand)Other oriented 5’ to 3’ (=lagging strand)
Why re multiple RNA primers needed
DNA pol dgenerates complimentary DNA (Okazaki fragments) to the strand between the RNA primers•Replication discontinuous as the new fragments are not joined
