What is the function of sugar in DNA?
DNA is one of the integral building blocks of life. It’s what makes you who you are on the most fundamental level. Strings of nucleotides form together in numerous different combinations, no two people being exactly the same even when they’re related by blood.
But what DNA is used to make is only half the story, the other being what DNA itself is made out of. There’s as much interesting information there as the entirety of a genetic code itself, the various parts of DNA all serving specific functions within its structure. And it all comes back to sugar.
Not the kind you’d find in a jar at home that you use to make sweets, but a sugar all the same. You may be asking yourself what this sugar is and why it’s inside every cell of your body, both very good questions. Let’s take a moment to go over that to explain why sugar is such an integral part of DNA.
What Sugar is in DNA?
The sugar found in DNA is called deoxyribose. If it sounds familiar, that’s because it’s not coincidentally the “D” in “DNA” – deoxyribonucleic acid.
In terms of chemical structure, deoxyribose is constructed of five carbon, ten hydrogen, and four oxygen (C5H10O4). These bind naturally to a phosphate molecule (structure PO4-) to become what’s dubbed the sugar-phosphate backbone of DNA. In this state, the compound can hold a nitrogenous base, being any one of adenine (A), guanine (G), cytosine (C), or thymine (T), specifically to the first carbon molecule in the sugar, conceptualized as the one furthest from the phosphate in models.
The nucleotides join together in strands to form the signature double helix look of DNA, the bases attaching across from one another on each strand complimentary in their base pairs (A to T and G to C) while the sugar-phosphate backbone joins into a continuous length to line them up. This both provides a solid structure to build the DNA from and offers a degree of protection to the bases in the center of the two sugar-phosphate strands holding everything together.
Various parts of the cell dictate in what order DNA is configured. This configuration, in turn, dictates how things like proteins will be formed, essentially affecting how the body itself is built. While the nitrogenous bases are what really determines this based on their arrangement, none of this would be possible without the sugar-phosphate backbone aligning them properly and offering them the support necessary to form into the double helix.
Is There a Different Sugar in DNA and RNA?
Like many things between the two, the sugars found in DNA and RNA are similar but not the same. Instead of deoxyribose, RNA is constructed of ribose (hence the R). Chemically, the two sugars are almost identical save for ribose adding a single oxygen molecule to its structure (C5H10O5).
While that may not seem like much of a difference, it makes both molecules quite easy to distinguish from one another. DNA is often formed into much longer strands than RNA, as well. It also influences how they bond to things like the nitrogenous bases, as well as the presence of uracil in place of thymine in the base pairs for RNA.
This also affects the stability of each acid. For one, DNA is far less reactive than RNA even in an alkaline solution, as lacking the additional hydroxyl bond on its second carbon like RNA (the extra oxygen molecule) leads to less chance of bonding with outside substances. RNA, however, will react with more readily with other substances because of that OH- in an attempt to balance itself. Even physically, these changes can be observed based on the depth of the grooves on each strands, with RNA featuring much deeper depressions on its surface that allow substances to pull it apart easier.
The differences continue in how DNA and RNA are treated by the body, too. DNA is continually protected within a cell’s nucleus, unable to leave. Other fixtures within the body are also set up to naturally reject enzymes or other substances that might wish to pull DNA apart save for during replication or when read by the RNA. Conversely, RNA is continually built, used, and broken down as part of its natural life cycle and is not as closely guarded as DNA, able to navigate out of the nucleus and to different parts of the cell as needed.
This resiliency does not extend to radiation, though, as ultra-violet rays are more likely to do serious damage to DNA as opposed to RNA. This stems largely from the fact that DNA is less likely to be broken apart, meaning mutation or damage typically stays within a gene affected by radiation while an affected RNA molecule is broken down and repurposed as it normally would be.
There are also the other differences in function between the two, such as DNA’s singular function of encoding genetics and RNA’s multiple forms and functions (mRNA for transmitting DNA messages to a cell’s cytoplasm, tRNA for transferring messages to the mRNA initially, rRNA for assisting in protein synthesis). Additionally, to accomplish all these functions, DNA is almost exclusively found in a double helix while RNA must be in a single strand.
Sugar is one of the fundamental parts of DNA. Deoxyribose is one of the two parts making up the sugar-phosphate backbone of all DNA strands, linking with a nitrogenous base in order to form a nucleotide. These link in pairs in great numbers forming the double helix shape of DNA.
Additionally, RNA also has a sugar known simply as ribose that serves much the same function as deoxyribose, differing only in a single elemental molecule. However, this single difference changes the way these two compounds behave, causing them to function as they do within the body’s cells.
While there’s plenty more to say about both DNA and RNA, this is the basic role sugar plays in their structure and functions within the cell.