Nucleic Acids and their Functions

Nucleic Acids and their Functions

Nucleic Acids: Basic Structure

  • Nucleic acids are complex organic substances that consist of nucleotide monomers linked in a chain through phosphodiester bonds.

  • A nucleotide consists of a nitrogenous base, a sugar (deoxyribose or ribose), and a phosphate group.

  • The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

  • The nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine, while in RNA they are adenine, uracil, cytosine, and guanine.

DNA: Structure and Role

  • DNA is a double helix structure made up of two antiparallel strands, secured by hydrogen bonds between base pairs.

  • The classic base pairing rules are A to T and C to G in DNA.

  • Replication of DNA is semiconservative, meaning that each new DNA molecule consists of one original and one newly synthesised strand.

  • DNA’s primary function is the storage and transmission of genetic information. It provides the instructions for protein synthesis.

RNA: Types and Functions

  • RNA is usually single-stranded and varies in length depending on its function.

  • There are three main types of RNA: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

  • mRNA carries the genetic information from DNA to the ribosome for protein synthesis.

  • tRNA transports the correct amino acid to the ribosome during protein synthesis.

  • rRNA combines with proteins to form the structure of the ribosome.

Protein Synthesis: Transcription and Translation

  • Transcription is the process of copying a segment of DNA into RNA. This occurs in the nucleus.

  • During translation, the mRNA sequence is decoded to build a chain of amino acids, ultimately creating a protein. This occurs at the ribosome.

  • Each set of three nucleotides on mRNA is a codon and each codon specifies a particular amino acid. This is how DNA’s code is translated into protein.

Gene Regulation

  • Not all genes are actively transcribed and translated. Gene regulation allows cells to respond to changes in their environment by controlling the synthesis of enzymes and other proteins.

  • Elements like promoters, operators, and enhancers in the DNA sequence, and proteins like activators and repressors, play a crucial role in gene regulation.