Molecular Biology 1 Flashcards
What is the flow of information in all living organisms (central dogma) ?
DNA –> RNA –> Protein
Replication, transcription/reverse transcription, translation
What are nucleotides made of ?
- Cyclic nitrogenous bases
- Pentose sugars
- Phosphate groups
What are the pyrimidines ?
C, T and U
What are the purines ?
A and U
Why are Guardian Angels are Pure and Two Winged ?
Because Guanine and Adenine are Purines and Two Ringed
How do we distinguish positions of the ribose ring form those of the base ring ?
Positions on the ribose ring are described with a prime (‘) to distinguish them from positions on the base ring.
What are nucleosides ?
Pentose + base ring
What are nucleotides ?
Phosphate group, pentose + base ring
How are polynuclotides formed ?
Successive (deoxy)ribose residues of a polynucleotide chain are joined by a phosphate group between the 3’ position of one sugar and the 5’ position of the next sugar.
One end of the chain (conventionally the left) has a free 5’ end and the other end has a free 3’ end.
What is Chargaff’s rule ?
[Purines] = [Pyrimidines] [A-T] = [G-C]
How many H-bonds link A-T ?
What about G-C ?
A-T –> 2 H-bonds
G-C –> 3-H-bonds
Is the DNA helix parallel or anti-parallel ?
Right or left handed ?
Anti-parallel right-handed double helix.
Give the following about DNA :
- number of base pairs/turn ?
- average rise/base pair ?
- helical diameter ?
- pitch ?
- number of base pairs/turn : 10.4
- average rise/base pair : 0.34 nm
- helical diameter : 2.4 nm
- pitch : 3.5 nm
What ends are produced by a 5’-3’ exonuclease ?
What about a 3’-5’ exonuclease ?
5’-3’ exonuclease : cleavage of phosphodiester bond leaves product with 5’-phosphate and 3’-hydroxyl ends
3’-5’ exonuclease : cleavage of phosphodiester bond leaves product with 3’-phosphate and 5’-hydroxyl ends
What kinds of nucleases exist ?
Are some specific ?
- DNAses and RNAses
- Endo- and Exonuclease
- Specific for dsDNA or ssDNA
- Restriction endonucleases cleave both strands of dsDNA at specific sequences
