Nucleic Acids

Nucleic acids Nucleic acids allow organisms to transfer genetic information from one generation to the next. There are two types of nucleic acids: Deoxyribonucleic acid, better known as DNA and Ribonucleic acid, known as RNA.

Nucleic acids- where are they?  The

nucleic acids are found in each and every cell of the body.  The DNA is found in the nucleus whereas the RNA is formed in the nucleus and found in the cytoplasm.  The DNA is located only in the nucleus.

Nucleic acids: What do they do?  DNA

in the nucleus is the control centre of the cell. All cellular activities are controlled by DNA.  The DNA is also responsible for passing the information from the parents to off springs.  The RNA is mainly involved in protein synthesis in a cell.

Structure of DNA

The structure of DNA molecule is made of:  Two

long chains made of chemical compounds called nucleotides and is called the DNA double helix.( also called the Watson – Crick model)  They are twisted against each other along a central axis.  Each nucleotide is made of a sugar, phosphate molecule and nitrogenous base.  It is permanently present in the cell.

Structure of the DNAcontinued   

Each nucleotide of a polynucleotide contains three parts: a. Phosphate group: This has the same structure in all the nucleotides. b. Pentose sugar: This sugar is made of 5 carbon atoms. Two types occur, ribose and deoxyribose. Ribose sugar is found in RNA and Deoxyribose sugar is found in DNA. The difference in the two sugars is- an oxygen atom is missing at the 2nd carbon atom of the ribose sugar in DNA. Hence it gets it s name - Deoxyribose.

Structure of the DNAcontinued  c.

Nitrogenous base: There are five different bases which are divided into two groups.  i) Pyrimidines: These are single rings each with six sides. They are Cytosine, Thymine and Uracil.  ii) Purines: These are double rings comprising a six-sided and a five-sided ring. They are Adenine and Guanine.

Structure of the DNAcontinued 1.

2. 3.

4.

Adenine always pairs with Thymine, with the help of two hydrogen bonds and Guanine always pairs with Cytosine with the help of three hydrogen bonds. This makes the two chains complimentary to each other. There are 10 basepairs per turn of the helix. The two chains and the nucleotides are nothing but a ladder like structure that is coiled upon itself. The two chains run in the opposite directions.

Nucleic acids- RNA  There

are three types of RNA in a cell  They are ribosomal RNA (rRNA), messenger RNA (mRNA) and transfer RNA ( tRNA).  Their main function is to make proteins after taking instructions from the DNA.  They are temporarily present in the cell.  There are 20 different tRNAs, for the different aminoacids.

Structure of Transfer RNA

structure of RNA - continued  Messenger

RNA is a single long chain of

nucleotides  Ribosomal RNA has two units, one large and the other small. Ribosomal RNA (rRNA)

Large subunit Small subunit

Nucleic acids

 List

the differences between DNA and RNA.  The answer should be in two columns, including location, structural and functional differences.