X-ray diffraction data collected by rosalind franklin and maurice wilkins watson and crick solve the structure of dna. which aspect structure of dna did the data them solve?
a. the double-stranded nature of the helix and its dimensions
b. the ratio of bases
c. the presence of deoxirybose sugars
d. the presence of hydrogen bonds between bases

The correct answer is option (A) the double-stranded nature of the helix and its dimensions.

Rosalind Franklin and Maurice Wilkins used a method of X-ray crystallography to investigate the structure of the DNA. It was a diffraction method and the scattering pattern of the X-ray was recorded on a film and used to elucidate details of molecular structure of the DNA. From the scattering pattern produced by the DNA molecule, they could infer the double helical nature of the DNA molecule and the arrangement of phosphates. They took the x-ray diffraction photograph of DNA known as the “photograph 51” depicting the double helix. By using this data about the double helical nature of the DNA, James Watson and Francis Crick proposed the structure of DNA in 1953.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.