One of the most common spontaneous lesions that occurs in DNA under physiological conditions is the hydrolysis of the amino group of cytosine, converting the cytosine to uracil. What would be the effect on DNA structure of a uracil group replacing cytosine?

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Hello everyone. Let's look at our next question. It says in a DNA molecule, what type of bond connects the nucleotides together. So when we think about each nucleotide being connected to the next. Um that type of bond is choice. See phosphor di ester bonds. And just to recall what those look like, we'll put up this little brief diagram here. Um We've got our two nucleotides. One up here, highlight that here, here's one nucleotide here and the other nucleotide here and here's our phosphate group we've got here. And the phosphate ester bond occurs when a hydroxyl group on this phosphate here reacts to the hydroxyl group on another molecule creating the di ester bonds as it does this on two different hydroxyl groups here. In this case this hydroxyl group with a three prime carbon on the deoxyribonucleic here. And this hydroxyl group reacting with the five prime carbon here. So that's our phosphate ester bond connecting our two nucleotides and going on to connect each nucleotide in the D. N. A. Polymer. But let's look at another answer choices here. Choice A. Says hydrogen bonds while hydrogen bonds are responsible for the um complementary base pairing. So between A. And T. Between C. And G. Creating that double helix shape but not for the connection between nucleotides which needs to be stronger bond than just hydrogen bonding where hydrogen bonds are of course relatively weak but all those hydrogen bonds between the complementary bases form that very stable um helical structure but not the answer that we're looking for choice B says co valent bonds. Um covalin bonds of course hold together every single um adam within the whole DNA molecule um but are not responsible. They're not the specific type that holds each nucleotide the next nucleotide. So that's why a covalin bond is not our correct answer. And then finally, Choice D ionic bonds. Um There are not any ionic bonds within the DNA molecule. The entire molecule itself is negatively charged and can form salts with positively charged ions. But you don't have ionic bonds connecting the nucleotides together. So that's why that's not a correct answer. So again, what type of bond connects the nucleotides together in the DNA molecule? Choice? See phosphor diaspora bonds. See you in the next video.

One of the most common spontaneous lesions that occurs in DNA under physiological conditions is the hydrolysis of the amino group of cytosine, converting the cytosine to uracil. What would be the effect on DNA structure of a uracil group replacing cytosine?

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Key Concepts

Spontaneous DNA Lesions and Deamination

Base Pairing and DNA Structure

DNA Repair Mechanisms for Uracil