DNA and RNA are both types of nucleic acid found in all living cells. DNA, or deoxyribonucleic acid, is used to store genetic information, while RNA, or ribonucleic acid, carries genetic information from the DNA to the ribosomes, which are the body's protein factories.
Structure of DNA and RNA Nucleotides
DNA and RNA are made of nucleotides, which are biological molecules consisting of a pentose sugar, a nitrogen-containing organic base, and a phosphate group. In a DNA nucleotide, the sugar is deoxyribose, while in RNA, it is ribose. Additionally, RNA contains uracil, while DNA contains thymine as a base. The nucleotides join together to form polynucleotides through a condensation reaction between the phosphate group of one nucleotide and the sugar of another, forming a phosphodiester bond.
Difference Between DNA and RNA
One key difference between DNA and RNA is in the bases they contain. DNA has adenine, thymine, cytosine, and guanine, while RNA has adenine, uracil, cytosine, and guanine. Moreover, DNA is made of two polynucleotide chains in a double-helix structure, with hydrogen bonding between the bases. Adenine pairs with thymine, and cytosine pairs with guanine, forming complementary base pairs. Meanwhile, RNA is a single-stranded molecule.
Function of DNA and RNA
The main function of DNA is to store genetic information, while RNA mainly serves to transfer genetic information from the DNA to the ribosomes, where it is used to produce polypeptides.
Differences Between Polynucleotides and DNA Double Helix
A polynucleotide is a polymer of nucleotides, while the DNA double helix is composed of two antiparallel polynucleotide strands twisting around each other. The complementary base pairing of adenine with thymine and cytosine with guanine results in the formation of the DNA double helix.
In conclusion, the structure of DNA and RNA and their functions are essential components of the study of AQA A Level Biology. Understanding the differences between DNA and RNA, as well as the formation of polynucleotides and the double-helix structure of DNA, is crucial for success in nucleic acids exam questions in A Level Biology.
