Related Concept Videos

Centrioles and Centrosomes01:13

Centrioles and Centrosomes

Most animal cells comprise a pair of centrioles together called a centrosome. The cell duplicates its centrosome and contains two centrosomes side-by-side, which begin to move apart during the prophase. As the centrosomes migrate to two different sides of the cell, microtubules start extending from each centrosome toward the other end. The mitotic spindle is composed of the centrosomes and their emerging microtubules.
Near the end of the prophase, also called late prophase or...
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Spindle Assembly02:50

Spindle Assembly

Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a...
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Histone Variants at the Centromere02:30

Histone Variants at the Centromere

Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3...
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Centrosome Duplication02:25

Centrosome Duplication

The primary microtubule organizing center (MTOC) in animal cells is the centrosome. A centrosome has two cylindrical centrioles at its core. Each centriole consists of nine sets of three microtubules held together by proteins. The centrioles are positioned at right angles to each other and surrounded by a shapeless protein cloud called the pericentriolar matrix, or pericentriolar material (PCM).
To ensure that each daughter cell receives a centrosome after cell division, centrosome duplication...
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Centrosome Duplication02:25

Centrosome Duplication

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Microtubule Associated Motor Proteins01:32

Microtubule Associated Motor Proteins

Eukaryotic cells have different motor proteins for transporting various cargo within the cell. These motor proteins differ based on the filament they associate with, the direction they move within the cell, and the type of cargo they transport. Motor proteins that associate with microtubules are known as microtubule-associated motor proteins. There are two families of microtubule-associated motor proteins —Kinesins and Dyneins. Both these proteins assist in the transport of cellular...
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