Question

1. Who were the guys who figured out the structure of DNA?
2. What did Rosalind Franklin contribute to the discovery?
3. How do the bases pair in DNA?
4. How did Franklin’s X-ray image and Chargaff’s rule help?
5. What function do the telomeres seem to serve?
6. For what do we use genetic engineering?

Answer 1

The structure of DNA was discovered by James Watson and Francis Crick. It is the contribution of Rosalind Franklin that led to the discovery. She worked on the X-ray diffraction images of DNA which confirmed the 3-D structure theory put forth by Watson and Crick.  

DNA comprises two purine bases namely Adenine and Guanine and two pyrimidine bases namely Thymine and Cytosine. Adenine pairs with Thymine with the help of two hydrogen bonds whereas Guanine pairs with Cytosine with the help of three hydrogen bonds.

The Chargaff's rule that helped Watson and Crick's DNA structure theory was that for the number of Adenine bases, there is an equal number of Thymine bases and for the number of Cytosine bases present in the DNA, there is an equal number of Guanine bases. Another crucial information that helped was that of Rosalind Franklin's. She came up with a clear, X-shaped diffraction pattern, which is famously known as "image 51" , which gave an important clue to Watson of as the image suggested a helical two-stranded structure of DNA .

Telomeres are repetitive sequences that are found at each end of chromosomes and they prevent deterioration of the chromosomes as well as their fusion with other chromosomes.

Genetic engineering is used to introduce a trait (gene) from one species to another. This is done for a variety of reasons. The reason could be to enhance the functionality, for example, the over-expression of RuBisCO is crop plants to improve their photosynthetic efficiency. Genetic engineering is also useful in gene therapy where diseases caused by a defective gene such as thalassemia or sickle cell anaemia that can be cured by introducing the correct gene that would restore the function. Genetic engineering is used to generate a variety of what are known as GM foods that are derived from plants that are modified genetically in order to confer disease resistance or improving its yield. But there are a lot of ethics involved on whether genetic engineering should be used as they might interfere with the natural order of things. It is feared that genetic engineering of crop plants may pose the risk of the foreign genes spreading to other plants as the pollen might fertilize other wild plants in the environment and disturb the ecosystem.