Mutants that cannot be expressed at all are called uninducible. Mutants that are continuously expressed are called constitutive mutants.

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#Id: 664

#Unit 3. Fundamental Processes

The meiotic telomere cluster is visualized by telomere fluorescent in situ hybridization (FISH). Microscopic image of a maize nucleus fixed at meiotic prophase (zygotene stage), subjected to telomere (green) and centromere (white) FISH, and counterstained for total DNA with DAPI (red).

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#Id: 665

#Unit 3. Fundamental Processes

“Quartets” of G residues is characteristic of Telomere

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#Id: 666

#Unit 3. Fundamental Processes

Short repeating sequence from the human telomere forms three stacked G quartets.

TLS Online TPP Program

#Id: 667

#Unit 3. Fundamental Processes

Telomerase, a reverse transcriptase that contains an RNA template, repeatedly adds TTAGGG repeats

TLS Online TPP Program

#Id: 668

#Unit 3. Fundamental Processes

Embryonic cells, germ-line cells, and stem cells produce telomerase, but most human somatic cells produce only a small amount of telomerase as they enter S phase.

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#Id: 669

#Unit 3. Fundamental Processes

As a result of their modest telomerase activity, their telomeres shorten with each cell cycle.