Overview of Nucleic Acids Structure

In this video, we will study about Nucleic Acids. Nucleic acids are basically biopolymers which are made up of monomeric units known as nucleotides. We have two important functions for nucleic acids that is they hold our genetic information and they perform variety of another functions that we will discuss later. We have two important types of nucleic acids in our body, the DNA and the RNA. Lets first try to understand the definition of Nucleic Acids. So, Nucleic acids are biopolymers. Bio means that they are synthesized inside biological systems and they are not synthetically synthesized. They are polymers which means they are made up of repeated units called as monomers which in this case are nucleotides. Now take this example. So, this is a cell. We have many different types of biopolymers in our body. One of them are the proteins. And most of you know that the proteins are made up of repeated units called as amino acids. Similarly, nucleic acids are also important biopolymers in our body, which are made up of repeated units which are known as nucleotides. So the next important thing is to understand the basic structure of a nucleotide, which will help us to understand the structure of nucleic acids in detail. Now this is a simple diagram explaining the structure of a nucleotide. As you can see, the single nucleotide is made up of three important groups, the phosphate, the sugar, and the nitrogenous base. And these groups are attached to one another by bonds, which we'll discuss later. To understand the complete structure of a nucleotide, let's try to understand the structure of these groups one by one. So the first is the sugar. The sugars present inside the nucleic acids are five carbon sugars. Now most of you know the six carbon sugars present inside the body and most important of them is the glucose. Now in chemical nomenclature all the six carbon sugars are called as hexoses. The word hex meaning six. There are different types of hexoses in our body other than glucose like the mannose and galactose. Similarly, 5 carbon sugars are called pentoses, the word pent meaning 5. There are different types of pentoses in our body but the two important types of pentoses that are present inside the nucleic acids are the ribose and deoxyribose. This is the simplified structure of the sugar present inside the nucleotide. Now if we compare this structure with the chemical structure of the ribose and deoxyribose on the right, you can see the structure clearly. We have carbon atoms on each of these corners. Note that the last carbon atom is located outside the ring. We have an oxygen atom at the center topmost position. You can also see in this chemical structure that the carbon atoms are named from 1 to 5 in a clockwise direction. So the carbon atom next right to the oxygen is called C1. So C2, C3, C4 and C5. C5 is located outside the ring. You can also see in this chemical structure we have different type of functional groups attached to these carbon atoms like the hydroxyl group and the hydrogen atom. The most important of these functional groups which determine whether the sugar is ribose or deoxyribose are present at the carbon number two and the carbon number three. In the sugar ribose we have a hydroxyl group that is attached to the carbon number two. This is the chemical structure of ribose. Now if you compare this structure with the structure of deoxyribose, the only major difference is that carbon number 2 that the carbon number 2 contains only a hydrogen atom and not the hydroxyl group. So the resultant sugar is called a deoxyribose. Here you can see the carbon number 2 in deoxyribose contains only a hydrogen atom whereas in ribose the carbon number 2 contains a hydroxyl group. You can also tell this by the difference in their names that the deoxyribose has a prefix called as deoxy which means removal of oxygen. The resultant sugar the deoxyribose is more stable as compared to ribose because of one less functional group. The deoxyribose is present in DNA and ribose is present in RNA. You can also remember this by the starting of the DNA which starts with D so the deoxyribose. and the RNA which starts with R so the sugar is the ribose. The next important group to study in a structure of nucleotide is the phosphate group which is this entity right here. The phosphate group consists of a phosphorus atom in the center to which four oxygen atoms are attached which are negatively charged. The phosphate group is the same phosphate group which is present in the adenosine triphosphate, the energy carrying molecule of the body. However, in ATP we have three molecules of phosphate which are attached to one another by high-energy phosphodiester bonds. The phosphate group is a polar molecule due to the presence of highly ionized oxygen atoms which impart negative charge to the phosphate group. Now the third important structure present in the structure of a nucleotide is the nitrogenous base. Nitrogenous bases are basically molecules that contain nitrogen in varying amounts and they act as a base. Most of you know that the human body contains organic chemicals which have carbon, hydrogen and oxygen in varying amounts. In nitrogenous bases, nitrogen combines with all of these atoms to form ring-like structures. These molecules are called bases since they can donate electrons to other molecules and form new molecules in this process. The nitrogen combines with all of these other atoms to form ringed structures. Now we can have two different types of ringed structures. One where there are single rings and second where there are double rings. The single rings are called Pyramidines and the double rings are called Purines. We have three different types of Pyramidines, the Thymine, Cytosine, and the uracil and we have two different types of purines called adenine and guanine. In the center you can see the chemical structure of each of these bases. As you can see the purines which are double ring structures adenine and guanine. Due to the presence of double rings these purines are larger as compared to the pyrimidines. The thymine, cytosine and uracil all are single ring structures and they are smaller as compared to the purines. The difference in the size of these bases is very important as it helps to pair these bases in the structure of DNA properly, which we will study later. So now you know the individual structures which are present in a single nucleotide. Next we will look at how these individual structures bond to each other to form a single nucleotide. And then we will look at how many nucleotides bind to each other to form a chain of nucleotides which is called a polynucleotide which can be either DNA or the RNA. So if we take a sugar and name just the important carbons here which will be the carbon number one and the carbon number five and of course you can see that at the carbon number two there is only a single hydrogen atom so this sugar will be a deoxyribose. Now to pair this deoxyribose sugar with this pyrimidine ring, the bond formed will be between the N1 of the pyrimidine ring and the C1 of the sugar. If you want to go into the details about how these nitrogens are named, you can check the link in the description below for the IUPSC nomenclature of the aromatic compounds. Now this bond will be an example of a glycosidic bond which is a covalent bond which links carbohydrates with other structures. Now if we have to pair a purine ring at a similar position, the bond formed will be between the N9 of the purine ring. Now next let's attach the phosphate. The phosphate group attaches with the carbon number 5 of the sugar. And the bond formed is the example of ester bond which is also a strong covalent bond. So now you know how the three structures in a single nucleotide bind to each other to form one nucleotide. Next, if we look at how many nucleotides bind to each other to form a chain of nucleotides called polynucleotides. So you can see basically what happens is that the phosphate group that attaches to the carbon number 5 of the sugar below also forms a bond with the carbon number 3 of the sugar above. And this pattern is repeated again and again. So you can see that the phosphate groups forms bonds both above and below the chain of these nucleotides. So as a result, a long chain of nucleotides is formed which consists of a sugar phosphate backbone and in the center we have all these nitrogenous bases which project from the sugar phosphate backbone. Now this can be an example of RNA if the sugar present in this example will be a ribose sugar. But if we take a similar strand of polynucleotide and run it in opposite direction and this strand binds with the original strand through hydrogen bonds. Now here comes the role of complementary base pairing. Now what complementary base pairing says that only adenine forms a hydrogen bond with thymine and only guanine forms a hydrogen bond with cytosine. Now this is a universal rule that is applied in the structure of a DNA. So here you can see adenine forms a hydrogen bond with thymine and similarly thymine forms hydrogen bond with only adenine. In similar case, gonine forms a hydrogen bond with cytosine and vice versa. Now this is the basic structure of DNA and you can compare this with the step ladder structure of the DNA. You can see that the supports of the ladder in the red are basically representing the sugar phosphate backbone and the rungs of the ladder represent the nitrogenous bases that are forming hydrogen bonds with each other. Now of course the original structure of DNA is that of a double helix so you can compare this structure with a double helix where the helices of this structure represent the sugar phosphate backbone and in the center you can see the red lines which represent the different nitrogenous bases that are forming bonds with each other. So this was an introductory video explaining you the structure of nucleic acids. In subsequent videos we will study in detail the structure of DNA, the structure of RNA, DNA replication, transcription, translation and many other topics. So make sure to subscribe to our channel for further upcoming videos and also make sure to like our Facebook page. page for all the notifications and flashcards. Thank you so much for watching.

We have two important types of nucleic acids in our body, the DNA and the RNA. Lets first try to understand the definition of Nucleic Acids. So, Nucleic acids are biopolymers. Bio means that they are synthesized inside biological systems and they are not synthetically synthesized. They are polymers which means they are made up of repeated units called as monomers which in this case are nucleotides.

Now take this example. So, this is a cell. We have many different types of biopolymers in our body.

One of them are the proteins. And most of you know that the proteins are made up of repeated units called as amino acids. Similarly, nucleic acids are also important biopolymers in our body, which are made up of repeated units which are known as nucleotides. So the next important thing is to understand the basic structure of a nucleotide, which will help us to understand the structure of nucleic acids in detail. Now this is a simple diagram explaining the structure of a nucleotide.

As you can see, the single nucleotide is made up of three important groups, the phosphate, the sugar, and the nitrogenous base. And these groups are attached to one another by bonds, which we'll discuss later. To understand the complete structure of a nucleotide, let's try to understand the structure of these groups one by one. So the first is the sugar. The sugars present inside the nucleic acids are five carbon sugars.

Now most of you know the six carbon sugars present inside the body and most important of them is the glucose. Now in chemical nomenclature all the six carbon sugars are called as hexoses. The word hex meaning six.

There are different types of hexoses in our body other than glucose like the mannose and galactose. Similarly, 5 carbon sugars are called pentoses, the word pent meaning 5. There are different types of pentoses in our body but the two important types of pentoses that are present inside the nucleic acids are the ribose and deoxyribose. This is the simplified structure of the sugar present inside the nucleotide. Now if we compare this structure with the chemical structure of the ribose and deoxyribose on the right, you can see the structure clearly. We have carbon atoms on each of these corners.

Note that the last carbon atom is located outside the ring. We have an oxygen atom at the center topmost position. You can also see in this chemical structure that the carbon atoms are named from 1 to 5 in a clockwise direction.

So the carbon atom next right to the oxygen is called C1. So C2, C3, C4 and C5. C5 is located outside the ring.

You can also see in this chemical structure we have different type of functional groups attached to these carbon atoms like the hydroxyl group and the hydrogen atom. The most important of these functional groups which determine whether the sugar is ribose or deoxyribose are present at the carbon number two and the carbon number three. In the sugar ribose we have a hydroxyl group that is attached to the carbon number two. This is the chemical structure of ribose.

Now if you compare this structure with the structure of deoxyribose, the only major difference is that carbon number 2 that the carbon number 2 contains only a hydrogen atom and not the hydroxyl group. So the resultant sugar is called a deoxyribose. Here you can see the carbon number 2 in deoxyribose contains only a hydrogen atom whereas in ribose the carbon number 2 contains a hydroxyl group.

You can also tell this by the difference in their names that the deoxyribose has a prefix called as deoxy which means removal of oxygen. The resultant sugar the deoxyribose is more stable as compared to ribose because of one less functional group. The deoxyribose is present in DNA and ribose is present in RNA.

You can also remember this by the starting of the DNA which starts with D so the deoxyribose. and the RNA which starts with R so the sugar is the ribose. The next important group to study in a structure of nucleotide is the phosphate group which is this entity right here. The phosphate group consists of a phosphorus atom in the center to which four oxygen atoms are attached which are negatively charged.

The phosphate group is the same phosphate group which is present in the adenosine triphosphate, the energy carrying molecule of the body. However, in ATP we have three molecules of phosphate which are attached to one another by high-energy phosphodiester bonds. The phosphate group is a polar molecule due to the presence of highly ionized oxygen atoms which impart negative charge to the phosphate group.

Now the third important structure present in the structure of a nucleotide is the nitrogenous base. Nitrogenous bases are basically molecules that contain nitrogen in varying amounts and they act as a base. Most of you know that the human body contains organic chemicals which have carbon, hydrogen and oxygen in varying amounts. In nitrogenous bases, nitrogen combines with all of these atoms to form ring-like structures. These molecules are called bases since they can donate electrons to other molecules and form new molecules in this process.

The nitrogen combines with all of these other atoms to form ringed structures. Now we can have two different types of ringed structures. One where there are single rings and second where there are double rings. The single rings are called Pyramidines and the double rings are called Purines.

We have three different types of Pyramidines, the Thymine, Cytosine, and the uracil and we have two different types of purines called adenine and guanine. In the center you can see the chemical structure of each of these bases. As you can see the purines which are double ring structures adenine and guanine.

Due to the presence of double rings these purines are larger as compared to the pyrimidines. The thymine, cytosine and uracil all are single ring structures and they are smaller as compared to the purines. The difference in the size of these bases is very important as it helps to pair these bases in the structure of DNA properly, which we will study later.

So now you know the individual structures which are present in a single nucleotide. Next we will look at how these individual structures bond to each other to form a single nucleotide. And then we will look at how many nucleotides bind to each other to form a chain of nucleotides which is called a polynucleotide which can be either DNA or the RNA. So if we take a sugar and name just the important carbons here which will be the carbon number one and the carbon number five and of course you can see that at the carbon number two there is only a single hydrogen atom so this sugar will be a deoxyribose. Now to pair this deoxyribose sugar with this pyrimidine ring, the bond formed will be between the N1 of the pyrimidine ring and the C1 of the sugar.

If you want to go into the details about how these nitrogens are named, you can check the link in the description below for the IUPSC nomenclature of the aromatic compounds. Now this bond will be an example of a glycosidic bond which is a covalent bond which links carbohydrates with other structures. Now if we have to pair a purine ring at a similar position, the bond formed will be between the N9 of the purine ring. Now next let's attach the phosphate.

The phosphate group attaches with the carbon number 5 of the sugar. And the bond formed is the example of ester bond which is also a strong covalent bond. So now you know how the three structures in a single nucleotide bind to each other to form one nucleotide. Next, if we look at how many nucleotides bind to each other to form a chain of nucleotides called polynucleotides.

So you can see basically what happens is that the phosphate group that attaches to the carbon number 5 of the sugar below also forms a bond with the carbon number 3 of the sugar above. And this pattern is repeated again and again. So you can see that the phosphate groups forms bonds both above and below the chain of these nucleotides. So as a result, a long chain of nucleotides is formed which consists of a sugar phosphate backbone and in the center we have all these nitrogenous bases which project from the sugar phosphate backbone. Now this can be an example of RNA if the sugar present in this example will be a ribose sugar.

But if we take a similar strand of polynucleotide and run it in opposite direction and this strand binds with the original strand through hydrogen bonds. Now here comes the role of complementary base pairing. Now what complementary base pairing says that only adenine forms a hydrogen bond with thymine and only guanine forms a hydrogen bond with cytosine. Now this is a universal rule that is applied in the structure of a DNA. So here you can see adenine forms a hydrogen bond with thymine and similarly thymine forms hydrogen bond with only adenine.

In similar case, gonine forms a hydrogen bond with cytosine and vice versa. Now this is the basic structure of DNA and you can compare this with the step ladder structure of the DNA. You can see that the supports of the ladder in the red are basically representing the sugar phosphate backbone and the rungs of the ladder represent the nitrogenous bases that are forming hydrogen bonds with each other.

Now of course the original structure of DNA is that of a double helix so you can compare this structure with a double helix where the helices of this structure represent the sugar phosphate backbone and in the center you can see the red lines which represent the different nitrogenous bases that are forming bonds with each other. So this was an introductory video explaining you the structure of nucleic acids. In subsequent videos we will study in detail the structure of DNA, the structure of RNA, DNA replication, transcription, translation and many other topics. So make sure to subscribe to our channel for further upcoming videos and also make sure to like our Facebook page.

page for all the notifications and flashcards. Thank you so much for watching.

Transcript for:Overview of Nucleic Acids Structure

Transcript for:
Overview of Nucleic Acids Structure