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Protein Synthesis

One of DNA’s functions is to form protein. This occurs through two stages:



Transcription is when a cell uses the information from a gene to form a strand of RNA. RNA and DNA are very similar because they both have the same structure, except that RNA is shorter than DNA and uses the sugar ribose. Also RNA does not have the base thymine; instead it has the base uracil.

The Difference Between RNA and DNA

During transcription, the type of RNA that is created is called mRNA or messenger RNA because it is used as a “messenger” to send information from a gene on DNA to a ribosome so that protein can be created.

RNA polymerase recognizes and attaches to a DNA nucleotide chain at the beginning of the gene, at a place called the promoter. The promoter positions the RNA polymerase on the right strand of DNA and guides it to the right direction.

As the RNA polymerase moves, it creates a new chain from the extra nucleotides. The RNA polymerase continues until it reaches a stop signal at the end of the gene.

The RNA polymerase then detaches itself from the DNA and the RNA chain is released, creating mRNA.

Here is an animation of the process of transcription.


Cytosine Guanine Adenine Thymine Uracil

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Once the mRNA takes the information from the DNA and sends them to the ribosomes, is translated into amino acid language. When the amino acid is created, it instantly folds to form protein that the gene in the DNA ordered.

The mRNA takes the information from the DNA and sends them to the ribosomes using the nucleotide language (the four letters).

A ribosome attaches to the mRNA near a place on the mRNA called the start codon, which is a three nucleotide bases that indicates where to start reading the message.

The amino acids that will later form protein are brought to the ribosomes while joined to transfer RNA or tRNA.

The tRNA converts the four-letters (the alphabet of nucleotides) into 20 letters (the alphabet of proteins).

The tRNA move the amino acids along the mRNAs so that the message can feed across the ribosome. There the amino acids are all linked together to form a protein chain.

Every organism on uses this process to make proteins.

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History of DNA >>

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