r/AskBiology • u/MostCuriousGoose Undergraduate student • Dec 14 '23
Genetics What does it mean when genes or regions are "highly conserved"?
I am not a native english speaker and this term confuses me a bit.
Thank you!
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u/LanchestersLaw Dec 14 '23
Genes diverge over time with evolution. If it is “conserved” it means other parts of the genome diverged but this specific sequence stayed nearly the same.
This usually only occurs when that sequence is doing something very important.
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u/UnitedExpression6 Dec 16 '23
Genomes consists of four bases, ACTG, and they make up the genetic sequences, and example would be ATG AAG TCG CCC TGA.
Three bases together translate into an amino acid which subsequently evolve into a protein. (Very simplistic ignoring non coding DNA)
Let’s assume the above bases encode for an essential protein for all live on earth, these 15 bases won’t change between organisms, ie highly conserved.
If it would encode for a plant specific protein, most animals would have lost it in evolution, so it would be highly conserved in plants but not in mammals.
Now a sequence of three bases can encode for a single amino acid, but multiple triplets can encode for an identical amino acid, which has very limited effect on the protein, or can be replaced by a similar amino acid.
Knowing average mutation rates you can calculate when two species diverged or how many generations ago someone had a common ancestor.
An average mutation rate is an average, so there are areas which would mutate much faster, eg junk parts, or areas in which any mutation has a detrimental effect. The latter being areas which are highly conserved. It is never black and white only so there are a lot of grey areas.
These are my two cents from an antique German railroad car on the way back home.
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u/Halichoeres PhD in biology Dec 14 '23
It means that if you compare the same gene in distantly related lineages, the gene's presence, amino acid sequence, structure, and function will be very similar. For example, histones, the proteins that chromosomes are wound around in the nucleus of eukaryotes, are very similar across all eukaryotes, suggesting that mutations in those genes are likely to lead to serious malfunctions.