Moving onto the fifth universal feature of all cells, per Alberts et al., is that:
The process of protein production actually baffled scientists up until the 50s, even though it was already understood that DNA is the basis of heredity. Since then, however, scientists have worked diligently at discovering how proteins are produced. It turns out that the process is more complex than we might think, and involves (to state it the most simply that I can), the translation of genetic information from mere As, Cs, Gs, and Ts of polynucleotides to a 20-letter alphabet, the one of proteins (Alberts et al. 2014).
How translation actually occurs might appear neat, rational, and orderly. In some ways, it is all of these things. But in other ways, translation is somewhat arbitrary. It should be realized, though, that the rules governing translation are, for the most part, the same for all living beings on the planet. The features that appear rather arbitrary are thought to be due to “frozen accidents” that took place early on in the history of life as we know it. These features are thought to have their roots in chance properties of the organisms that were some of our earliest ancestors, which were passed on genetically, and which have over time become so deeply embedded into the constitution of all cells that are living, that changing them would result in perilous happenings (Alberts et al. 2014).
Somewhere in the ribosome, a large multimolecular machine that is made up of protein and something called ribosomal RNA, a process occurs, with a number of different steps. This process will be discussed in far more detail later, but it is helpful to have an idea of how they work. Information that is in the sequence of a messenger RNA molecule actually starts off by being grouped into three-nucleotide sequences at a time. These three nucleotides that are grouped together are known as a codon, and they specify or code for one amino acid in a corresponding protein. Because there are four codons and we are forming nucleotide triplets, 64 combinations for different codons can occur, but in actuality, only 20 amino acids exist. So, it just so happens to be the case that a few different nucleotide triplets can code for the same amino acid. Next, transfer RNA molecules read out the genetic code. Transfer RNA molecules, or tRNA molecules, then attach at one end to a particular amino acid. At the other end, an anticodon is displayed. An anticodon is a specific sequence of three nucleotides that allows tRNA molecules use base-pairing to recognize a specific codon or subset of codons in messenger RNA. All of this intricate chemistry occurs within the ribosome (Alberts et al. 2014).
Hopefully you understood what this was all about. You will soon be introduced to these properties and topics in a more detailed manner, such as in later chapters within different texts. So far, if you understand just the basics of what is being said, you are doing pretty well! Keep it up!
A prospective medical student, looking to help others succeed.