Final answer:
Regions of chromatin located near centromeres and at telomeres containing numerous short sequences are called constitutive heterochromatin, which is a permanently tightly packed chromatin structure as opposed to the less condensed euchromatin associated with active gene transcription.
Step-by-step explanation:
Regions of the chromatin containing numerous, short, tandemly repeated sequences that are located near the centromeres and at the telomeres of eukaryotic chromosomes are called constitutive heterochromatin. In eukaryotic cells, chromatin organizing in the nucleus has different structural regions. The heterochromatin is the tightly packed form, which usually contains genes that are not actively expressed.
Constitutive heterochromatin is specifically found at the structural parts of chromosomes such as the centromeres and telomeres. This form is a permanent feature in the cells and differs from facultative heterochromatin, which can change depending on the cell's stage and types. Alternatively, euchromatin is less condensed and associated with active gene expression, allowing easier access for replication and transcription.