why do purines bond with pyrimidines in the dna ladder

Why do purines bond with pyrimidines? December 2, 2013,
Genetic materials such as DNA and RNA are the language of life. All of the world s living organisms are imbued with a blueprint for their creation. And that blueprint is written in the language of either DNA or RNA. Purines and pyrimidines form the building block for the making of DNA (also known as deoxyribonucleic acid). The structure of genetic material is so basic that there are only two purines and three pyrimidines in total. That s right, just five chemicals that make up the entire genome of every single organism that exists today. rPPurines are bigger, with two rings of base, and pyrimidines are smaller, with only one ring. The two purines are adenine and guanine, and the three pyrimidines are cytosine, thymine and uracil. Uracil is present only in RNA. The structure of, and the best way to think of that is to imagine a ladder that s been twisted like a spiral. The sides of the ladder are made of purines and pyrimidines.

Each rung of the ladder is a hydrogen bond between a purine and a pyrimidine. But why do purines only bond with pyrimidines? Why aren t there bonds between two purines, or bonds between two pyrimidines? There are two reasons for this. The first reason is that the distance between the two strands of DNA is constant. Two purines together would be too big to fit in that distance, and two pyrimidines together would be too small. The second reason is that the bonding between purines and pyrimidines is very specific. Not only can a purine not bond with anything but a pyrimidine, but specific purines have to bond with specific pyrimidines. This is because the structure of each is such that it can only bond with the corresponding one. The bonding rules are This specific bonding pattern or rule is called Chargaff s rule, after the scientist who discovered it. So specific bonding rules, secondary to structure, and a constant distance between the two spirals, are the reason why purines only bond with pyrimidines.

Why do hindus wear a red dot? Why do ceiling fans make noise? 1. What is the difference between the purines and the pyrimidines? The difference between the purines and pyrimidines are the rings. Purines (adenine and guanine) have two carbon nitrogen ring bases. While pyrimidines ( thymine and cytosine) have one carbon ring. 2. Why do you think purines bond with pyrimidines in the DNA ladder? I think purines bond with pyrimidines in the DNA ladder because adenine molecules only pair thymine molecules and guanine molecules only pair with cytosine molecules. A and T bond with 2 hydrogen bonds, C and G bond with 3 hydrogen bonds. 3. DNA has two strands. If the sequence of nucleotides of one strand was known, is it possible to use that information to determine the sequence of the second strand? Explain your reasoning for your response. If one strand of DNA was known it is possible to use that information to determine the sequence of the second strand because A pairs with T and C pairs with G and there are four possible combinations that your could choose because the second strand is usually opposite from the first stand. 4.

Carefully compare your model to the model created by another group. Are the two models exactly the same? If they are not exactly the same, explain how they differ from one another and how these differences relate to human differences. My model isn't exactly like another groups DNA but they differ because other groups DNA is not in the same order as mine. This is like human differences because not everyone has the same DNA order or the same types of codes. 5. Label the following on the diagram of DNA below: a base pair, a nucleotide, a deoxyrobose sugar, and a phosphate group. Designate at least one adenine (A), thymine (T), cytosine (C), and guanine (G) with the appropriate letter.

  • Views: 45

why does a dna molecule seldom replicate incorrectly
why does dna contain thymine rather than uracil
why does dna contain thymine instead of uracil
why does dna contain thymine and rna uracil
why does dna contain thymine and not uracil
why do we have d n a
why is thymine replaced by uracil in rna