I know that it has to do something with primers and the whole anabolic process of replication, but how? What happens that makes DNA shorter with each replication? Is RNA-primers getting cut off with DNA? Explain like i am five
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My understanding is that the telomers get shortened with each replication as a result of the inability to form the final Okazaki fragment in the lagging strand. If you visualize replication of the lagging strand, the RNA primer needs to affix to the Strand a certain number of bases down from where the last okazaki fragment annealed into place. If there is not enough length to the strand, there is not enough room for the replication machinery to properly replicate the remaining nucleotides of the lagging strand, causing the telomers to shorten with every replication.
Imagine your DNA is a ladder, and it’s suspended in space. Imagine a man starting at the top of the ladder, climbing his way down. The man can replicate rungs on the ladder with his hands, but he can’t replicate the rung he is standing on because he will fall off. As he climbs down, he keeps replicating each rung he passes, but eventually he reaches the bottom of the ladder and is standing on the bottom rung. He can’t replicate that rung since he is actively standing on it, and if he were to step off the rung he would fall off and still not be able to replicate that last rung, so he calls it quits there and wraps up his job, replicating the entire ladder except the very last rung.
Nothing on a gene level, really.
When DNA gets read, it unzips. The two halves split apart. At this point it can either be used to make RNA to be sent off to make proteins, or it can be copied into new DNA.
When your cells divide, it is being copied.
When the DNA is unzipped like this, it’s less stable, so it’s more likely for the DNA to be damaged. It’s most unstable at the ends because there’s fewer molecules there to hold it in place. It’s like string fraying at the ends. This DNA at the ends that can be lost are called telomeres. It’s basically some junk DNA that doesn’t really code for anything and can be lost without consequence. It’s once those telomeres are gone that your important DNA can be damaged.
DNA doesn’t get shorter with every replication.
mRNA that has been ~~translated~~ **transcribed** from your DNA gets shorter with each time it is ~~transcribed~~ **translated** into a protein.
This is by design so cells don’t overrun with mRNA segments. And acts Sorta like a timer. Make gene X so many times or for however long.
There is damaging a telomere shortening that occurs with age but isn’t a regular mechanism occurring at each replication.
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