How can a cell make many different kinds of proteins out of only 20 amino acids? Of the myriad possibilities, how does the cell 'know' which proteins to make?

Verified step by step guidance

1. Understand the basic building blocks: Recognize that proteins are made up of amino acids, and there are 20 different standard amino acids that can be combined in various sequences to form a vast array of proteins. Each protein's unique function and structure are determined by the specific order and composition of these amino acids in its polypeptide chain.
2. Learn about genetic coding: Know that the instructions for building proteins are encoded in the DNA of the cell. Each gene in the DNA sequence corresponds to a specific protein. The sequence of nucleotides in the DNA determines the sequence of amino acids in the protein, which is dictated by the genetic code. This code is universal and specifies which amino acids will be added during protein synthesis based on the sequence of three nucleotides (codon).
3. Explore transcription and translation processes: Understand that the process of making a protein from DNA involves two main steps: transcription and translation. During transcription, a segment of DNA is copied into mRNA (messenger RNA), which then travels from the nucleus to the ribosome. In translation, the ribosome reads the mRNA sequence and assembles the amino acids in the correct order to form a protein.
4. Examine regulation of protein synthesis: Learn how cells control which proteins are made through various regulatory mechanisms. These include controlling when and how often a gene is transcribed, processing and modifying mRNA after transcription, and regulating the stability and translation of mRNA. These mechanisms ensure that proteins are made at the right time, in the right place, and in the right amounts.
5. Consider the role of environmental and cellular signals: Recognize that cells respond to internal and external signals that can influence which proteins are produced. These signals can come from other cells, from changes in the environment, or from the cell's own internal state. The cell integrates these signals to make decisions about which proteins are needed at any given time, allowing it to adapt to changing conditions.