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Replication in Eukaryotes

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before cell division, so there are many proteins that fulfill specialized roles in the replication process. Replication occurs in three phases: initiation, elongation, and termination, and ends with two complete sets of chromosomes in the nucleus.
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...

Replication in Eukaryotes

Replication in Eukaryotes

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Telomeres and Telomerase

In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded DNA.

Telomeres and Telomerase

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In eukaryotic DNA replication, a single-stranded DNA fragment remains at the end of a chromosome after the removal of the final primer. This section of DNA cannot be replicated in the same manner as the rest of the strand because there is no 3’ end to which the newly synthesized DNA can attach. This non-replicated fragment results in gradual loss of the chromosomal DNA during each cell duplication. Additionally, it can induce a DNA damage response by enzymes that recognize single-stranded DNA.

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Replicative cell senescence is a property of cells that allows them to divide a finite number of times throughout the organism's lifespan while preventing excessive proliferation. Replicative senescence is associated with the gradual loss of the telomere — short, repetitive DNA sequences found at the end of the chromosomes. Telomeres are bound by a group of proteins to form a protective cap on the ends of chromosomes. Embryonic stem cells express telomerase — an enzyme that adds the telomeric...

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Related Experiment Video

Updated: Jun 12, 2026

Telomere Length and Telomerase Activity; A Yin and Yang of Cell Senescence

Telomere Length and Telomerase Activity; A Yin and Yang of Cell Senescence

Published on: May 22, 2013

Improving precision in investigating aging: why telomeres can cause problems.

The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences

|June 12, 2010

Summary

This summary is machine-generated.

Telomere length discrepancies between studies question its reliability as a biomarker of aging. Measuring CDKN2A levels may offer a more robust alternative for bio-aging assessment.

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Area of Science:

Biogerontology
Biomarker Discovery

Background:

Recent studies reveal discrepancies in telomere length measurements across different study scales (lab vs. clinical/epidemiological).
These inconsistencies question the robustness of telomere length as a universal biomarker for aging across physical, sociological, and psychological parameters.

Discussion:

Differing methodologies in telomere length assessment are a likely source of discrepancies.
CDKN2A (cyclin-dependent kinase inhibitor 2A) measurement shows promise, with reproducible data and superior predictive capacity for organ function in some clinical studies compared to telomere length.

Key Insights:

Telomere length's reliability as a bio-aging biomarker is challenged by measurement variability.
CDKN2A emerges as a potential alternative biomarker with demonstrated clinical utility.

Outlook:

Standardized, multicenter, double-blinded studies are crucial for validating bio-aging biomarkers.
Investigating telomere length and CDKN2A, alone or in combination, is recommended to identify optimal aging assessment methods.