a) (i) Name the segment of DNA shown in the diagram - HSC - SSCE Biology - Question 33 - 2014 - Paper 1

DNA has a remarkable ability to repair itself through various mechanisms. Enzymes recognize damaged areas and can remove or replace incorrect nucleotides. Notable repair processes include:

1. Base Excision Repair: This mechanism removes damaged bases and replaces them with the correct nucleotides.
2. Nucleotide Excision Repair: This method removes a section of the DNA strand that contains the damage and fills in the gap with new nucleotides.
3. Mismatch Repair: This corrects errors that occur during DNA replication, ensuring that the proper base pairs are formed.

Thus, the processes not only help maintain genetic integrity but also prevent mutations from occurring.

To summarize the process of gene cloning, here is a flow chart for cloning the human insulin gene:

1. Isolate the Gene: Extract the human insulin gene from human DNA.
2. Insert into Vector: Use enzyme restriction and ligation processes to insert the insulin gene into a bacterial plasmid.
3. Transformation: Introduce the recombinant plasmid into a bacterial cell.
4. Culture Bacteria: Grow the bacteria in a suitable culture medium, allowing them to replicate.
5. Harvest Insulin: Collect and purify the insulin produced by the bacteria.

This flow shows the essential steps involved in cloning a specific gene, illustrating the biotechnology involved.

Blood groups and highly variable genes are both utilized in paternity testing, but they serve different roles.

1. Blood Groups: Though blood groups can indicate possible parentage, they lack specificity. For instance, if both alleged parents have type A blood, a child could also have type A or O blood. This provides limited evidence for paternity.

2. Highly Variable Genes: Markers such as short tandem repeats (STRs) offer a more definitive analysis. Since these genes vary significantly among individuals, the probability of matching them between alleged parent and child is high if they are related. For instance, if an STR match is found, it strongly supports biological parenthood.

In conclusion, while blood groups can indicate potential relationships, highly variable genes provide more reliable evidence for confirming paternity.