Here's a breakdown:
* DNA: DNA is made up of four nucleotide bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). These bases are arranged in specific sequences that contain the genetic instructions for building and maintaining an organism.
* RNA: DNA's genetic code is transcribed into messenger RNA (mRNA), which carries the instructions to the ribosomes.
* Ribosomes: Ribosomes are the protein synthesis machinery in cells. They read the mRNA sequence and use it to assemble amino acids into a protein chain.
* Genetic Code: The genetic code is a set of rules that determines how a sequence of three nucleotides (a codon) in mRNA corresponds to a specific amino acid. There are 64 possible codons, but only 20 amino acids are commonly found in proteins. Some amino acids are encoded by multiple codons, making the code redundant.
Key Features of the Genetic Code:
* Triplet: Each codon consists of three nucleotides.
* Non-overlapping: Codons are read one after the other, without overlapping.
* Universal: The genetic code is nearly universal across all living organisms, with only a few minor variations.
* Degenerate: Most amino acids are encoded by more than one codon.
Example:
The codon AUG codes for the amino acid methionine and also acts as the start codon.
The codon UAA is a stop codon, signaling the end of protein synthesis.
Understanding the genetic code is fundamental to understanding how genes are expressed and how proteins are made.
