If DNA is different for everyone, how can proteins be the same?

Question

certain proteins are same in everyone..

for instance, enzymes.. some hormones.. etc..

also, proteins are made from mRNA, which is made from DNA.

DNA sequences differ in everyone, making everyone different from one another's..

their DNA is transcribed as it is.. obviously different people will be having different mRNAs as well..

Now, my question is,

from the specific sequences of base pairs of DNA, in different individuals, how can same proteins be formed??

Answer 1

Basically our proteins aren't necessarily the same.

However, most of our genetic material is identical or at least extremely similar and for many genes there is no variation. We then come to things called single nucleotide polymorphisms which is what you mean, this is where it is common for there to be several variants of a single nucleotide within a gene. These are NOT mutations, they are normal variations that are confered from your parents genes. Mutations are accidental damage to the DNA altering its base sequence but most mutations actually physically damage the chemical structure of the DNA itself requiring large areas of DNA to be replaced with new bases.

Bear in mind that both UUU and UUC code for phenylalanine as an example, most amino acids have several different codons that will create that amino acid. So I may have a UUU and you may have a UUC codon in one of our genes, but its mostly irrelevant because when the protein is transcribed it will still have phenylalanine as the base.

Then bear in mind that amino acids are a bit like lego bricks, you stick them together in a certain order to create shapes. Some shapes are very common like the alpha helix and the beta pleated sheet structures. Some amino acids are very simple, i like to think of them like the single lego block, you can replace them with many different amino acids (lego blocks) and still obtain the same end shape because its simple. Other amino acids are very complex in structure, and these are more like a wheel type lego brick, you cant just replace it with any other brick to make the same end shape.

Now that may not make sense but hopefully this will explain it... lets say you have a serine base where I have a threonine base. If you look up the structures for those two you will see they are basically identical only threonine has an extra carbon side chain off to one end. In most cases they will have the same shape within a protein, and so wont disrupt its function. SO despite having two different amino acids our protein is basically the same.

Now lets say I have a glycine where you have a tyrosine. They are totally different shapes, one is small and simple, the other has a ring structure so chances are this will change the structure of that protein and it may work in different ways or not at all.

Maybe its a pigment protein, maybe that variation has caused my version of the protein to absord green light giving me green eyes, while yours picks up blue light giving you blue eyes.

Remember that proteins often have up to several thousand amino acids so having one that is different isn't likely to change the end result unless its in a very important place. Again think of proteins like lego models, will a lego model of 1000 bricks be that different if one of them were changed to a differently shaped brick? - probably not, unless it was in a very important place.

The variations in our genes are visible all over us, they are visible in how quickly we get tired, the way we look, how we eat and drink, how we process alcohol and other substances. They are visible in when we die and what we die of etc.

I hope this helps.

Answer 2

Most of the DNA in people is identical. The important ones, such as genes that code for the protein hemoglobin is usually the exact same as other peoples'. Many DNA sequences differ in places that don't matter as much - like in a tandem repeat or something. Using this, we can use RFLP (Restriction Fragment Length Polymorphism) analysis to determine the difference in a person's genome, once combined with gel electrophoresis.

Another possibility is because of the redundant effect of DNA. Multiple DNA sequences can code for the same amino acid, thus not affecting the overall codon that is produced in the mRNA. Even further, just because a single codon is different and produces a different amino acid, there is still a possibility that the overall protein can still function.

Answer 3

no idea lol