Podcast
Questions and Answers
What is the primary reason telomeres cannot be fully replicated by standard DNA replication machinery?
What is the primary reason telomeres cannot be fully replicated by standard DNA replication machinery?
- Telomeres are inherently resistant to DNA polymerase binding due to their secondary structure.
- DNA polymerase requires a free 5' end to initiate replication, which is absent at telomeres.
- The lagging strand synthesis cannot proceed to the very end of a linear template due to the requirement of a primer. (correct)
- Telomerase actively degrades the ends of the lagging strand.
How does telomerase prevent the loss of genetic information during DNA replication?
How does telomerase prevent the loss of genetic information during DNA replication?
- By adding non-coding repetitive sequences to the 3' end of the DNA strand. (correct)
- By preventing the unwinding of the DNA double helix.
- By degrading damaged DNA and replacing it with new nucleotides.
- By proofreading the DNA sequence and correcting any errors.
What component within telomerase is directly responsible for its ability to extend telomeres?
What component within telomerase is directly responsible for its ability to extend telomeres?
- Telomere-binding proteins that recruit DNA polymerase.
- Associated helicases that unwind the telomeric DNA.
- A guide RNA that provides the template for telomere sequence addition. (correct)
- A catalytic protein subunit with reverse transcriptase activity.
Telomerase uses reverse transcription to elongate the DNA. What is the template for this reverse transcription?
Telomerase uses reverse transcription to elongate the DNA. What is the template for this reverse transcription?
What is the telomere sequence?
What is the telomere sequence?
How many bases of the telomerase pair with the last bases of the DNA?
How many bases of the telomerase pair with the last bases of the DNA?
What happens once the DNA is long enough?
What happens once the DNA is long enough?
What happens to the primer after the DNA strand is synthesized?
What happens to the primer after the DNA strand is synthesized?
Telomerase elongates the parent DNA strang, by adding non-coding repetitive sequences, in such a way so that what needs to be removed?
Telomerase elongates the parent DNA strang, by adding non-coding repetitive sequences, in such a way so that what needs to be removed?
In which types of cells can lots of telomerases be found?
In which types of cells can lots of telomerases be found?
Besides stem cells, what other types of cells upregulate their telomerase activity to constantly elongate the DNA and allow for constant replication?
Besides stem cells, what other types of cells upregulate their telomerase activity to constantly elongate the DNA and allow for constant replication?
Which aspect of telomere maintenance is most critical for preserving genomic stability in dividing cells?
Which aspect of telomere maintenance is most critical for preserving genomic stability in dividing cells?
In the context of cancer cells, what is the most likely consequence of upregulated telomerase activity?
In the context of cancer cells, what is the most likely consequence of upregulated telomerase activity?
Considering the mechanism of telomerase, what would be the most direct effect of a mutation that disrupts the reverse transcriptase activity of the enzyme?
Considering the mechanism of telomerase, what would be the most direct effect of a mutation that disrupts the reverse transcriptase activity of the enzyme?
If a cell lacked the ability to remove the RNA primer after DNA replication, what immediate consequence would this have on the newly synthesized strand during telomere replication?
If a cell lacked the ability to remove the RNA primer after DNA replication, what immediate consequence would this have on the newly synthesized strand during telomere replication?
What is the crucial role of the RNA component within the telomerase enzyme complex?
What is the crucial role of the RNA component within the telomerase enzyme complex?
Why is the process so that the overhang needs to be removed, not the actual DNA?
Why is the process so that the overhang needs to be removed, not the actual DNA?
If you could introduce a change that would prevent the loss of any important genetic information, besides telomerase existing, what option would be the best?
If you could introduce a change that would prevent the loss of any important genetic information, besides telomerase existing, what option would be the best?
Given a scenario where a somatic cell inappropriately expresses telomerase at high levels, what is the most likely long-term consequence?
Given a scenario where a somatic cell inappropriately expresses telomerase at high levels, what is the most likely long-term consequence?
Regarding the end replication problem, what is the fundamental reason why the lagging strand cannot be fully replicated in linear chromosomes?
Regarding the end replication problem, what is the fundamental reason why the lagging strand cannot be fully replicated in linear chromosomes?
Flashcards
Telomeres
Telomeres
DNA sequences at the ends of chromosomes, protecting them from deterioration or fusion with neighboring chromosomes.
Lagging Strand Issue
Lagging Strand Issue
During DNA replication, the lagging strand cannot replicate to the very end of the template because it lacks a 3' end, resulting in telomere shortening.
Telomerase
Telomerase
An enzyme that adds DNA sequence repeats to the 3' end of DNA strands in the telomere regions.
Telomerase RNA Template
Telomerase RNA Template
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Telomerase Function (in short)
Telomerase Function (in short)
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Telomerase and Cell Replication
Telomerase and Cell Replication
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Study Notes
- During DNA replication, when the lagging strand reaches the template's end, the telomere cannot complete the strand due to the lack of a 3' end.
- To prevent the loss of genetic information, telomerase elongates the telomere.
- Telomerase contains its own RNA template, which is complementary to the telomere sequence (TTAGGG).
- The last two bases of telomerase pair with the last two bases of the DNA.
- Telomerase starts reverse transcription to elongate the DNA.
- Once the DNA is long enough, telomerase detaches, and primase creates a primer for synthesizing a new DNA strand.
- The primer gets removed but is not replaced with DNA nucleotides; instead, the template used to make the primer is removed.
- Telomerase extends the parent DNA strand, ensuring the overhang that needs removal is not the actual DNA.
- Stem cells have a high concentration of telomerases.
- Cancer cells enhance their telomerase activity to continuously elongate their DNA and facilitate replication.
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