These two scientists represent the men, James Watson and Francis Crick, who were the two people credited with discovering the correct shape of DNA, a double-helix. They did this experiment in the 1950s with the help of fellow scientist, Rosalind Franklin, who was not credited for the discovery because she had died of cancer. Rosalind had identified the repeating pattern of the DNA.
Erwin Chargaff was an important scientist in the 1950s. He made two important discoveries about DNA. His two discoveries were both made into new laws of science. The first being the amounts of Thymine and Adenine are identical (T=A), and the amount of Cytosine is identical to the amount of Guanine (C=G). This meant that Thymine and Adenine were always paired together, and Cytosine and Guanine were too. Erwin's second rule was, DNA of different species differs in the amount Adenine and Guanine.
A chromosome is a structure that holds DNA and its proteins.
A karyotype is a picture of a persons siploid set of chromosomes.
The replication of DNA starts with the unraveling of the double helix. This is done by breaking the hydrogen bonds holding the helix together. Once this is done, the new strands of DNA are made and proofread. Once everything in the strand of DNA is proofread and correct, the DNA is replicated.