The human body is made up of trillions of individual cells. And within each of those cells, strands of DNA are stored in 23 packages, called chromosomes. The DNA acts like a code to control how the cell (and the whole body) functions. DNA, which is a chemical compound, stands for deoxyribonucleic a, but you may know it as a long series of A’s, C’s, G’s, and T’s. Each of the four letters stands for a type of nucleotide molecule: A is adenine, C is cytosine, G is guanine, and T is thymine (see image). Together, they act as instructions that our bodies read to perform functions by making proteins. (Learn more about protein synthesis here.) Through chemical bonds, the nucleotides form a long, two sided spiral where adenine matches up with thymine, and cytosine matches up with guanine (see Image 2).
Genetic code is in all living things, including the microorganisms that makes up microbiomes. Scientists can extract the genetic code, and sequence it to determine what microbes are in the sample.
Image 1: DNA chemistry
Image 2: Nucleotide matches
RNA is similar to DNA. While DNA is in a two sided, ladder-like structure, RNA is like one side of it. There are three major types of RNA: mRNA, tRNA, rRNA. At the surface level, mRNA is essential for protein synthesis and is created by the RNA polymerase enzyme from the parental DNA. The enzyme goes through the process of transcription by moving along the selected piece of DNA, splitting the two sides apart, and formulating messenger RNA (mRNA) from the corresponding nucleotide of the DNA (a cytosine if there’s a genuine, uracil if there’s a adenine, etc.). rRNA, also known as ribosomal RNA, makes up the organelle that makes proteins called the ribosome. How rRNA functions in eukaryotes [a] vs prokaryotes [b] is slightly different, but in terms of microbiomic analysis (because the majority of microorganisms are prokaryotes), the latter is more important. tRNA is crucial to the process of protein synthesis. Structured like a clover, transfer RNA is used to ‘read’ the mRNA and build a chain of amino acids [c] which forms a protein.
Image 3: Types of RNA
