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Related Concept Videos

Gene Evolution - Fast or Slow?02:05

Gene Evolution - Fast or Slow?

The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
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Non-LTR Retrotransposons03:18

Non-LTR Retrotransposons

As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...
Bacterial RNA Polymerase00:43

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
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Bacterial Transcription

RNA polymerase (RNAP) carries out DNA-dependent RNA synthesis in both bacteria and eukaryotes. Bacteria do not have a membrane-bound nucleus. So, transcription and translation occur simultaneously, on the same DNA template.
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Gene Evolution - Fast or Slow?02:05

Gene Evolution - Fast or Slow?

The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
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Pre-mRNA Processing: Modification of pre-mRNA Ends

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Related Experiment Video

Updated: Jun 28, 2026

Assessment of DNA Contamination in RNA Samples Based on Ribosomal DNA
13:16

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Published on: January 22, 2018

Identification of human Rap1: implications for telomere evolution.

B Li1, S Oestreich, T de Lange

  • 1The Rockefeller University, New York, New York 10021, USA.

Cell
|June 13, 2000
PubMed
Summary

Researchers identified human Rap1 (hRap1) as a telomeric protein orthologous to yeast Rap1. This finding helps explain the absence of some mammalian telomeric proteins in budding yeast and suggests evolutionary conservation of telomere components.

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Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • Mammalian telomeres possess proteins like TRF1, TRF2, tankyrase, and TIN2, which lack clear counterparts in budding yeast.
  • The evolutionary relationships of telomeric proteins across different yeast species and mammals remain incompletely understood.

Purpose of the Study:

  • To identify and characterize orthologs of yeast telomeric proteins in mammals and fission yeast.
  • To elucidate the evolutionary history and conservation of telomeric protein complexes.

Main Methods:

  • Sequence homology analysis to identify conserved motifs between human and yeast Rap1.
  • Telomere localization studies using cellular imaging techniques.
  • Functional assays to assess the impact on telomere length maintenance.

Main Results:

  • A human protein, hRap1, was identified as an ortholog of the budding yeast telomeric protein scRap1p, sharing conserved sequence motifs.
  • hRap1 localizes to telomeres and influences telomere length, but unlike scRap1p, it is recruited by TRF2.
  • The fission yeast protein Taz1 was identified as a TRF ortholog, indicating TRF conservation.

Conclusions:

  • The findings suggest that ancestral telomeres contained both TRF-like proteins and Rap1, similar to vertebrates.
  • Budding yeast may have retained Rap1 at telomeres while losing the TRF component, potentially linked to changes in telomeric repeat sequences.