Hey, everyone. So before we talk about nucleic acids, it's first important to talk about what is a nucleotide. Now a nucleotide represents a monomer or single unit of a nucleic acid. Here, a nucleic acid is just a polymer of nucleotides that store and encode genetic information. And when we talk about nucleotides, we're going to say there are two types. We have DNA and we have RNA. DNA represents deoxyribonucleic acid and RNA represents ribonucleic acid. With DNA, we're going to say that it stores genetic information of cellular organisms. We're going to say RNA, while it transfers this genetic information from DNA in order to create proteins later on. Now, here, we said that these are two types of nucleotides. It's important to talk about the components of a said nucleotide. Now, here, before we can talk about a nucleotide, we need to talk about its precursor, which is the nucleoside. A nucleoside consists of two things. It consists of a pentose sugar and a nitrogenous base. If we take a look here at this structure before the arrow on the left side of the arrow, we have our pentose sugar and we have our nitrogenous base. So this is a nucleoside. A nucleotide consists of this nucleoside plus a phosphate group. So as we follow the arrow towards the right side, we've attached a phosphate group to our equation here. So, a nucleotide, its three components are a phosphate group, a pentose sugar, and a nitrogenous base. So just remember these key terms when we're talking about nucleotides, nucleosides, and nucleic acids overall.
Intro to Nucleic Acids - Video Tutorials & Practice Problems
Intro to Nucleic Acids Concept 1
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Intro to Nucleic Acids Concept 2
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In this video, we'll talk about RNA nucleotides versus DNA nucleotides. Now, here we're going to say that our pentose sugar in RNA is ribose, and when it's DNA, it's 2-deoxyribose. Now, here is some important terminology. When we say deoxy, "deoxy" just means without oxygen. So, if we take a look at the image on the left side, we're going to say that this here will represent our RNA nucleotide. We're going to say here that our RNA nucleotide has a phosphate group, its pentose ring, and its nitrogenous base. Remember, those three components make up a nucleotide. Here, though, because it's RNA, the pentose ring is a ribose sugar. Because it's a ribose sugar, it has an OH group right here. When we talk about DNA, so here we're looking at the DNA nucleotide. It's a nucleotide, so it still has the 3 components that make it up, which is a phosphate group, a ring, a pentose ring, as well as a nitrogenous base. But, because it's DNA involved, we're not going to have an OH here, we're going to have just an H with lost oxygen. So that's why we're going to call this a deoxyribose sugar. Right? So just remember, these are the key differences between DNA and RNA.
Intro to Nucleic Acids Example 1
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In this example question, it says, select the correct statement describing nucleotides. Here, the sugar in DNA has an extra OHgroup than the sugar in RNA. Now remember, deoxyribose sugar is indicative of DNA. That means we've lost an oxygen. So we wouldn't have an extra OHgroup. All nucleotides contain a nitrogenous base. This is true. Remember, nucleotides have 3 components: a phosphate group, our pentose ring, as well as a nitrogenous base. So this is true. Here, the sugar in DNA contains one less carbonyl group than the sugar in RNA. So remember, what's the difference between RNA and DNA? We have one less oxygen in DNA. That's why it's deoxyribose sugar involved. Here, all nucleotides containing ribose sugar. This is not true. DNA represents a sugar or it represents a nucleotide, actually, And DNA does not have a ribose sugar. It has a deoxyribose sugar because it has one less oxygen. So here, the only statement that's true is option b. All nucleotides contain a nitrogenous base.
