Guanine and adenine are purines (named for their double ring structure) while cytosine, thymine, and uracil are pyrimadines (for their single ring structure). The fourth base in DNA is thymine (T) and the fourth base in RNA is uracil (U). DNA and RNA share three bases: adenine (A), guanine (G), and cytosine (C). Sugars are numbered from the most highly functionalized carbon (so the carbon bonded to both an oxygen and the nitrogenous base in the DNA example above) starting with 1, where these carbons are referred to as 1’ (one prime), 2’ (two prime), etc. In DNA and RNA, the sugar is a ribose (hence collectively they can be referred to as ribo nucleic acids), which is a 5-carbon sugar that forms a pentagon shape (pentose). Here's an a I put a thymine so that's it pretty straight forward it's much like DNA just with those little differences one mnemonic or trick to help you remember the key difference of using uracil instead of thymine is remember what's the abbreviation for uracil, it will be the letter u so just think in your head you are correct and if you are, you are correct.All nucleic acids are comprised of three structural components: a sugar, a phosphate, and a nitrogenous base (a structure containing nitrogen DNA if we're binding DNA to RNA and we have a RNA adenine here this would have to be a thymine for DNA but if I was making an RNA to RNA where I have an adenine I'll have to use uracil which you'd abbreviate u so if I have my RNa strand here that's a, c, a I follow the standard base pairing rules of a to t or u, g to c so here's the c there's a guanine or g. Remember that RNA does not use thymine it uses uracil. For short portions however you can and the way you can form an RNA to RNA strand or RNA to DNA strand follows the same base pairing rules that DNA does with a lot of twist. Well RNA can't do that but because without addition oxygen that's on this carbon right there it tends to make it unstable for long stretches to be in a double helical form. Now you're familiar with this with DNA and you know that DNA often twist up to form the very famous double helix. a nucleotide and you bring the phosphate group of the next one in and it joins a phosphate to that sugar and then you extend that and so you windup with a long strand of RNA nucleotides with their bases sticking out with the phosphates and sugars forming the backbone of the strand. You take our phosphate and sugar and nitrogenous base i.e. Now to join RNA molecules together it works pretty much the same way as joining DNA molecules together. The other difference that you'll see in the structure of the nucleotides is that it uses the same guanine and adenine and cytosine that DNA uses but instead of using thymine uses a particular kind of pyrimidine called uracil. deduct it, then I deoxygenated this ribose here and look all that's left is the hydrogen so that's the difference between ribose and deoxyribose sugar. Deoxyribose can you guess which one uses that? You're right! DNA which stands for Deoxyribose Nucleic Acid while RNA Ribonucleic acid uses ribose and if you look at the names they look very similar in fact if I cover up the deoxy I see the word ribose, what does that mean? Well this is ribose notice down here on the second carbon there's an OH group or hydroxyl group for those who are doing Chemistry. Well deoxyribose and ribose are the two sugars. Now one of the differences to bear in mind between DNA and RNA is what is that pentose sugar. Just like DNA it has a phosphate group then gives it a strong negative charge, it has a five carbon sugars sometimes called a pentose and some kind of nitrogen containing base or nitrogenous base. The basic building blocks that make up RNA are nucleotides just like with DNA. It's the workers that help carry out some of the information and instructions of the DNA and it's built together much like DNA is so let's take a closer look. DNA is a really long molecule RNA is typically a shorter molecule but it's just as important as DNA. It's the one that takes the information that's being stored in DNA and sends it out to the cell so that the cell can actually use that info- information. When people think about nucleic acids, they typically think of DNA but there's another molecule RNA which is just as important.
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