Cell biology: telomers

[pkrpkrpkr]

I have a, probably stupid question.
Please explain to me as if I was a 5-year old and I might
actually understand this. Thank you!

When replicating, the DNA polymerase needs pre existing bases
to continue base pairing and replication. That is why primers
are used. There is a problem here though. At the very tip of the
chromosome there is no place to put the primer, it would be "hanging"
in the air. Instead the problem is solved by telomerase adding some
nucleotides on the template strand, putting down a primer and then
engaging DNA polymerase.

But it also says in my book that w/o telomers the replicated, new strand,
would shrink for every replication. I CANNOT understand this. Let's say
we put the RNA primer at the tip - but not "outside of the tip" - of the
chromosome. We then continue the RNA sequence with DNA using DNA polymerase.
We then remove the primer and fill the gap with DNA using repair DNA polymerase
and ligase. How on earth has this shortened the chromosome???

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[Drrrrrr. Celty]

The lagging strand gets shorter because of the 5-3' transcription and it being 3-5' in orientation and problems with primers. The end is always going to have a primer and that primer that binds to the DNA and falls off. Thus leaving a chunk of DNA missing.
The primer imitates transcription for the polym

 

[NeuralNetwork]

http://www.youtube.com/watch?v=AJNoTmWsE0s

 

[JRWPREMED]

The lagging strand gets shorter because of the 5-3' transcription and it being 3-5' in orientation and problems with primers. The end is always going to have a primer and that primer that binds to the DNA and falls off. Thus leaving a chunk of DNA missing.
The primer imitates transcription for the polym

If you don't mind me asking, what class is this covered in? I've taken both Freshman Bio courses, and it never went into this kind of depth. Is this Biochemistry or Cell/Molecular Bio?

 

[mmmcdowe]

If you don't mind me asking, what class is this covered in? I've taken both Freshman Bio courses, and it never went into this kind of depth. Is this Biochemistry or Cell/Molecular Bio?

I had it in both biochem and cell bio, but I think I had at least some of this in gen bio....

 

[JRWPREMED]

I had it in both biochem and cell bio, but I think I had at least some of this in gen bio....

My Bio class went over the basics of this, but never in depth with telomerase and primers. I'm starting my Cell and Molecular Bio class in 3 days. Hopefully it will go into depth a bit more.

 

[Drrrrrr. Celty]

If you don't mind me asking, what class is this covered in? I've taken both Freshman Bio courses, and it never went into this kind of depth. Is this Biochemistry or Cell/Molecular Bio?

Genetics and Gen Bio for me.