GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
DNA must be replicated before a cell can divide
|
|
|
viruses enter cells without their protein coat
|
|
|
only protein from the infecting phage can also be detected in progeny phage
|
|
|
the amount of cytosine equals the amount of guanine
|
Detailed explanation-1: -Chargaff’s rules state that in the DNA of any species and any organism, the amount of guanine should be equal to the amount of cytosine and the amount of adenine should be equal to the amount of thymine. Further a 1:1 stoichiometric ratio of purine and pyrimidine bases (i.e., A+G=T+C ) should exist.
Detailed explanation-2: -Chargaff’s rule states that the amount of adenine (A) is equal to that of thymine (T) and the amount of guanine is equal to that of cytosine (C) in an organism.
Detailed explanation-3: -Chargaff’s rules states that DNA from any cell of all organisms should have a 1:1 ratio of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.
Detailed explanation-4: -Cytosine always pairs with guanine, so their percentages will also be equal.
Detailed explanation-5: -Erwin Chargaff (1905-2002) showed experimentally that base compositions actually varied among species. Within any one species, however, the molar ratios [A] = [T] and [C] = [G] are constant, and the proportion of [C+G] < [ A+T ]. These ratios have since been referred to as “Chargaff’s Rules".