Semi-Conservative Replication (AQA A Level Biology)
Revision Note
Written by: Lára Marie McIvor
Reviewed by: Lucy Kirkham
The Purpose of Semi-Conservative Replication
Before a (parent) cell divides, it needs to copy the DNA contained within it
This is so that the two new (daughter) cells produced will both receive the full copies of the parental DNA
The DNA is copied via a process known as semi-conservative replication (semi = half)
The process is called so because in each new DNA molecule produced, one of the polynucleotide DNA strands (half of the new DNA molecule) is from the original DNA molecule being copied
The other polynucleotide DNA strand (the other half of the new DNA molecule) has to be newly created by the cell
Therefore, the new DNA molecule has conserved half of the original DNA and then used this to create a new strand
The importance of retaining one original DNA strand
It ensures there is genetic continuity between generations of cells
In other words, it ensures that the new cells produced during cell division inherit all their genes from their parent cells
This is important because cells in our body are replaced regularly and therefore we need the new cells to be able to do the same role as the old ones
Replication of DNA and cell division also occurs during growth
Examiner Tips and Tricks
Make sure you don’t confuse ‘parent cell’ with ‘parent organism’. A parent cell is any cell in the body that divides into two cells and the terminology is used to refer to the ‘original’ cell that the DNA came from before it was split and replicated semi-conservatively.
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