It is a less invasive surgery, so your recovery time is shorter and easier than with mastectomy. Lumpectomy has a few potential disadvantages: You are likely to have 5 to 7 weeks of radiation therapy, 5 days per week, after lumpectomy surgery to make sure the cancer is gone.
DNA: Double Helix. The secondary structure of DNA is actually very similar to the secondary structure of proteins. The protein single alpha helix structure held together by hydrogen bonds was discovered with the aid of X-ray diffraction studies. The X-ray diffraction patterns for DNA show somewhat similar patterns.
The double helix describes the appearance of double-stranded DNA, which is composed of two linear strands that run opposite to each other, or anti-parallel, and twist together.Each DNA strand within the double helix is a long, linear molecule made of smaller units called nucleotides that form a chain.n 1953, Francis Crick and James Watson first described the molecular structure of DNA, which they called a double helix, in the journal Nature.