This video, I found to be very educational. It’s done by one of three medical students who call themselves “The Salmonella Place”. They do videos based on several aspects of Medicine, Biochemistry being one of them.
The video begins with an introduction of nucleic acids, and their relation to DNA and RNA. A nucleic acid contains a chain of nucleotides linked together with covalent bonds to form a sugar-phosphate backbone with protruding nitrogenous bases. They are linear, biological molecules which are essential to life. The nucleotides are the basic unit of the nucleic acid. These molecules are able to store and express genetic information.
Next in the video, the tutor explains that nucleotides comprise of a nitrogenous Base, Pentose sugar and one to three Phosphates. Pentoses in the nucleic acid include Ribose and Deoxyribose which have bicarbons.
The base of the nucleotide is considered to be heterocyclic which simply means that there are two different rings of atoms- Nitrogen ring and Carbon ring. The base binds at position 1 or Carbon 1. The are two bases in nucleic acids. These are called Purines, which comprise of Adenine (A) and Guanine (G) and Pyridmidines which comprise of Cytosine (C), Thymine (T) and Uracil (U). Cytosine is found in both DNA and RNA, whereas Thymine is found only in DNA and Uracil, only in RNA. Between Adenine and Thymine there are 2 hydrogen bonds and between Guanine and Cytosine there are 3 hydrogen bonds. These are more heat resistant.
The phosphate groups are simply phosphate atoms surrounded by 3 hydroxyl (-OH) groups and an oxygen atom. Phosphate groups can bind both at the 3′ and 5′ position.
As compared to the nucelotide, the nucleoside lacks phosphate but comprises of only a nitrogenous base covalently attached to a pentose (ribose or deoxyribose). The formation of a nucleoside is due to the removal of the phosphate group of a nucleotide via hydrolysis.
He also spoke about a phosphodiester bond which is a covalent bond in RNA or DNA that holds a polynucleotide chain together by joining a phosphate group at position 5 in the pentose sugar of one nucleotide to the hydroxyl group at position 3 in the pentose sugar of the next nucleotide. This is called also a phosphodiester linkage.
Furthermore on nucleotides, they form ATP or Adenosine Triphosphate which is used for energy and storage. Also, they form the Cyclic Adenosine Monophosphate or CAMP which is used for regulatory functions.
Lastly, nucleotides are named after the base component. For example, with the base Adenine, the nuceloside will be Adenosine, Thymine, would be Thymidine. When a nucleotide is named after the base, it is also named after the number of phosphate groups. For example, a nucleoside with 1 phosphate group is called Monophophate such as AMP- Adenosine Monophosphate.
This video was found to be brief and informative, and I do hope you enjoy! 😀
Biochem and I 