How do we know that G pairs with C and that A pairs with T as complementary base pairs are formed?

Question

Accepted Answer

Everyone. Let's take a look at this practice problem together. One complete D. N. A. Helical turn has 10 base pairs. What will be the total number of hydrogen bonds in a turn if there are four adenine bases present so we know that one turn equals 10 base pairs and that there are four adnan's present. Now recall that adenine is always bonded with timing and so that is a base pair. So that means out of the 10 there will be four adenine thiamine base pairs Which means 10 - equals six. So there's going to be six cytosine guanine base pairs. So how many hydrogen bonds are in each of these base pairs? Well let's take a look at the chemical structure of these base pairs and compare them. So here we have the chemical structures and if we look at our bonding between adenine and timing you'll note that there are two hydrogen bonds. And then if you look at the bonding between cytosine and guanine there are three. So we have two hydrogen bonds for added in timing and three hydrogen bonds for cytosine and guanine. Now there actually is an equation that we can use in order to solve this problem. And it's that the total number of hydrogen bonds equals two times the number of adding timing based pairs. Plus three times the number of cytosine guanine, these pears. So let's go ahead and plug in the information we know. So we're going to have two times four because there are four adding timing based pairs Plus three times cytosine guanine base pairs. And now we'll just do our math. So we have two times four plus three times six. So that's gonna be eight plus 18 which will give us 26 total. So there will be 26 hydrogen bonds and that is going to be answered. D. 26. Alright, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.

How do we know that G pairs with C and that A pairs with T as complementary base pairs are formed?

Verified video answer for a similar problem:

Key Concepts

Base Pairing Rules

Chargaff's Rules

X-ray Crystallography of DNA