Explain how the discoveries by Rosalind Franklin helped Watson and Crick build an accurate
model of DNA.

In 1951 Franklin joined the Biophysical Laboratory at King’s College, London, as a research fellow. There she applied X-ray diffraction methods to the study of DNA. When she began her research at King’s College, very little was known about the chemical makeup or structure of DNA. However, she soon discovered the density of DNA and, more importantly, established that the molecule existed in a helical conformation. Her work to make clearer X-ray patterns of DNA molecules laid the foundation for James Watson and Francis Crick to suggest in 1953 that the structure of DNA is a double-helix polymer, a spiral consisting of two DNA strands wound around each other.

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.