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Which is not consistent with double heli...

Which is not consistent with double helical structure of DNA?

A

`A=T, CequivG`

B

Density of DNA decrease on heating

C

`A + T//C + G` is not constant

D

Both (a) and (b)

Text Solution

AI Generated Solution

The correct Answer is:
To determine which statement is not consistent with the double helical structure of DNA, we can analyze the given statements based on our understanding of DNA structure and properties. ### Step-by-Step Solution: 1. **Understanding the Double Helical Structure**: The double helical structure of DNA, proposed by Watson and Crick in 1953, consists of two strands that coil around each other. Each strand is made up of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base. 2. **Analyzing Chargaff's Rules**: Chargaff's rules state that in a double-stranded DNA molecule, the amount of adenine (A) is equal to thymine (T) and the amount of guanine (G) is equal to cytosine (C). This means that A + T is equal to G + C, which is a crucial aspect of the DNA structure. 3. **Evaluating the Density of DNA on Heating**: When DNA is heated, it undergoes denaturation, where the hydrogen bonds between the base pairs break, causing the double-stranded DNA to separate into single strands. This process results in a decrease in density because the tightly packed double helix becomes two separate strands. 4. **Assessing the Statement about A + T and G + C**: The statement "A + T upon G + C is not constant" contradicts Chargaff's rules. According to these rules, the ratio of A + T to G + C should be constant and is typically taken as 1 in a stable double-stranded DNA molecule. 5. **Conclusion**: The statement that "A + T upon G + C is not constant" is incorrect and therefore not consistent with the double helical structure of DNA. ### Final Answer: The statement that is not consistent with the double helical structure of DNA is: **"A + T upon G + C is not constant."** ---
To determine which statement is not consistent with the double helical structure of DNA, we can analyze the given statements based on our understanding of DNA structure and properties. ### Step-by-Step Solution: 1. **Understanding the Double Helical Structure**: The double helical structure of DNA, proposed by Watson and Crick in 1953, consists of two strands that coil around each other. Each strand is made up of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base. 2. **Analyzing Chargaff's Rules**: Chargaff's rules state that in a double-stranded DNA molecule, the amount of adenine (A) is equal to thymine (T) and the amount of guanine (G) is equal to cytosine (C). This means that A + T is equal to G + C, which is a crucial aspect of the DNA structure. ...
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