THE MOLECULAR BASIS OF INHERITANCE
DNA MAKES RNA MAKES PROTEIN
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
adenine
|
|
|
cytosine
|
|
|
guanine
|
|
|
uracil
|
Detailed explanation-1: -Replication relies on complementary base pairing, that is the principle explained by Chargaff’s rules: adenine (A) always bonds with thymine (T) and cytosine (C) always bonds with guanine (G).
Detailed explanation-2: -Under normal circumstances, the nitrogen-containing bases adenine (A) and thymine (T) pair together, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA .
Detailed explanation-3: -Guanine and thymine are similarly incompatible. A always pairs with T and G always pairs with C because these are the only combinations that allow for hydrogen bonding to occur, given the spatial constraints of the double helix, which requires there to be one purine and one pyrimidine in each base pair.
Detailed explanation-4: -The need for accuracy probably explains why DNA replication occurs only in the 5′-to-3′ direction. If there were a DNA polymerase that added deoxyribonucleoside triphosphates in the 3′-to-5′ direction, the growing 5′-chain end, rather than the incoming mononucleotide, would carry the activating triphosphate.
Detailed explanation-5: -In base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.