On the PBS site, read the DNA introduction, then proceed to the “DNA Workshop Activity.” Complete the activity.- Now watch the animation on the McGraw-Hill site.
Helicase unwinds the DNA and separates the 3’ from the 5’ strands of DNA by breaking the hydrogen bonds between the 2 complementary strands. DNA Polymerase adds nucleotides to the free 3’ end and this synthesis works continuously in the 5’ to 3’ direction and is known as the leading stand. The free 5’ end is known as the lagging strand and this synthesis is more complex. DNA polymerase can only add new deoxyribonucleotides to a free 3’ OH. RNA primase adds to a free 3’ OH on the lagging strand and synthesizes a short primer, which the DNA polymerase III adds to the 3’ end of the RNA primer. Then, the DNA polymerase I replaces DNA polymerase III, and then replaces the RNA with DNA. At the end, ligase forms a bond between the 3’ OH and the 5’ phosphate.
- Now, proceed to “All Wound Up” on the PBS site.
- Briefly describe the structure of a chromosome in complete sentences. Include the major building blocks and how they are put together.
- Now looks at the “People” section on the PBS site.
Crick created a visual model of DNA.
Franklin made advances in x-ray diffraction techniques with DNA.
Wilkins along with Franklin proposed the structure of DNA.
Watson discovered that DNA was made of two chains of nucleotides.
- Describe two controversies surrounding the race to discover the structure of DNA. What is your opinion about each? Would the same controversies exit today? Why or why not?
The scientists had strained relationships with one another because of withholding information from one another and not letting their “partners” know when they do share information with the “opposing team.” I think this will still take place today because in today’s society people are still competitive and manipulative. However, it simply depends on the individuals involved. Hopefully, scientists today will strive to make discoveries for the good of mankind rather than to be credited with the innovation.