Watson and Crick were the first two scientists to discover the double helix model of DNA. Rosalind Franklin and Maurice Wilkins also helped Watson and Crick but they did not receive any credit.
Chargaffs Rule is that DNA from cells should have a 1:1 ratio of pyramidine and purine bases and that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.
Base pairs bind when the two bases hold the two strands of DNA together.
A chromosome is a structure of nucleaic acids and it is a protein in the nucleas. It also carries genetic information.
A karyotype is the number of chromosomes in a cell nuclei.
A cell first has to copy all its DNA then it can divide into two cells. When a cell divides into two it is called mitosis. Each cell gets their own copy of DNA and 46 chromosomes.
DNA can be damaged by many things, such as a break in the strand of DNA, a base missing from the backbone of the DNA, or a chemically changed base.