Molecular Biology and Genetics - Lecture Twelve : DNA replication
4 important questions on Molecular Biology and Genetics - Lecture Twelve : DNA replication
What are the 7 proteins/enzymes involved for DNA replication ?
- Helicase : Unwinding of strand
- Single Stranded binding proteins : Prevention of unwound DNA from degrading or rejoining
- Primase : A starting point for nucleotide additions, adds RNA nucleotides
- DNA Polymerase 3 : Progressive addition of new nucleotides from the priming sequence
- Topoisomerase : Release of tension, by cutting and sticking back together
- DNA Polymerase 1 : removes RNA primer and fills it with DNA
- Ligase : Sticks newly synthesised fragments together of DNA together
What are the mechanisms of DNA replication ?
- DNA replication is the formation of two strands of DNA from one template molecule
- DNA synthesis always occurs in the 5’ to 3’ direction
- Bidirectional : Replication happens in two directions from a single point of origin
- Semi-discontinuous : Leading and Lagging Strand
How can errors in the DNA sequence be corrected and why is it important ?
❖ After Replication Endonuclease: The endonuclease removes the error, plus flanking regions. DNA polymerase I comes in and makes new DNA, ligase joins new DNA to existing DNA
IMPORTANCE ??
If not corrected, the wrong bases become a permanent part of the DNA. Every cell from this one with the mutated DNA will also have the “incorrect” genetic information. This is not always bad, this is how we get genetic variation.
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What is PCR and What does it stand for?
- The acronym stands for Polymerase Chain Reaction.
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