Important SynthesisProtein synthesis is the process in which DNA is eventually converted into amino acids that form proteins. Proteins carry out many of the important functions within your body. In the case of hemochromatosis, a protein that your body normally should make is either not created or not functioning due to mutations in the HFE gene. Below we will explore how a mutation in the DNA could translate into the wrongful production of proteins.
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Transcription
The process of transcription occurs in the nucleus. It is the first step in the process of protein synthesis. RNA polymerase unwinds and splits the double helix of DNA to two separate strands, only doing this in the specific DNA portion that it needs for the desired protein. mRNA makes a copy of the DNA strand that it is working with by creating a string of complementary bases. mRNA copies the DNA so it does not have to leave the nucleus itself, keeping it protected. Whenever DNA has an A, instead of copying it with the complementary T, RNA uses an U in its place instead. The mRNA knows when to start and stop coding based on the specific order that the DNA nucleotides have (example: UAG is a stop codon).
RED: Example of a mutated and duplicated portion of DNA that will code for hemochromatosis (visit mutation page for more information). The amino acid that was supposed to be created has been changed in this example to one that will affect the eventual protein created.
DNA: TAC GAT GAT ATC
mRNA: AUG CUA CUA UAG
RED: Example of a mutated and duplicated portion of DNA that will code for hemochromatosis (visit mutation page for more information). The amino acid that was supposed to be created has been changed in this example to one that will affect the eventual protein created.
DNA: TAC GAT GAT ATC
mRNA: AUG CUA CUA UAG
Translation
Once mRNA has left the nucleus, translation can occur. mRNA travels to the ribosomes within the cytoplasm where the rest of the process can occur. mRNA attaches itself to one of the ribosomes. The code sequence that mRNA has is divided into nucleotide sets of 3, known as codons. These mRNA codons are then copied by the tRNA which creates an anticodon and eventually an amino acid based on the code it read. The amino acids that the tRNA produces are attached by peptide bonds to later form proteins. This process occurs until a stop codon is read.
mRNA: AUG CUA CUA UAG
tRNA: UAC GAU GAU AUC
Amino Acids: Methionine, Leucine, Leucine, Stop
This is an example of a mutation on the HFE gene. This mutation causes the incorrect amino acids to be created which also changes the eventual protein that is created. For our purposes, this mutation causes hemochromatosis in the individual as the protein that detects iron levels in the blood will either not be present or will not be functional with this duplicated amino acid.
mRNA: AUG CUA CUA UAG
tRNA: UAC GAU GAU AUC
Amino Acids: Methionine, Leucine, Leucine, Stop
This is an example of a mutation on the HFE gene. This mutation causes the incorrect amino acids to be created which also changes the eventual protein that is created. For our purposes, this mutation causes hemochromatosis in the individual as the protein that detects iron levels in the blood will either not be present or will not be functional with this duplicated amino acid.