DNA Ester Bonds?

[juantonwan]

 

I have been recommending this YouTube video to people, which seems to be pretty well done. But I have been getting questions back, which I couldn't really answer.

 

I have received some comments about how the hydrogen cyanide and ammonia solution would become oxidized and would not produce adenine. But the response to that is that there was no oxygen in the earth's early atmosphere. - A good video to watch is "How the earth was made" a 2 part History channel documentary.

 

Question:

 

In DNA and RNA, where did ester bonds come from? Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. However, according to scientific theory, in the earth's early atmosphere there was no oxygen, so how could phosphodiester bonds have been formed to make up the backbone of DNA, since ester bonds require oxygen? Without these bonds, you couldn't have DNA or RNA.

[John Cuthber]

Two thirds of the earth's surface is covered with water and 88% of the mass of that water is oxygen.

(things may have been a bit different back then, but oxygen wouldn't have been rare)

[juantonwan]

Two thirds of the earth's surface is covered with water and 88% of the mass of that water is oxygen.

(things may have been a bit different back then, but oxygen wouldn't have been rare)

 

Okay, got it. It is thought that asteroids blasted the earth and brought in most of the water from space. Then it rained for millions of years. This is estimated 4.4 billion years ago, so there would have been all the water on the earth prior to the emergence of the first single-celled organism 2 billion years ago. This would have produced some atmospheric oxygen.

 

So then how would you counter the statement that the hydrogen cyanide, ammonia solution becoming oxidized which would not allow adenine to be produced?

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Its like if you say there was oxygen, adenine couldn't have been produced. But if you say there was no oxygen, ester bonds could not have been formed. How do you address this?

[Mr Skeptic]

You confuse oxygen with free oxygen (ie, an oxidizing atmosphere). Sand is more than half oxygen, and water far more, but don't try breathing it.