Sage-Tips

What are microtubules and where can they be found?

Microtubules are major components of the cytoskeleton. They are found in all eukaryotic cells, and they are involved in mitosis, cell motility, intracellular transport, and maintenance of cell shape. Microtubules are composed of alpha- and beta-tubulin subunits assembled into linear protofilaments.

Are microtubules in the nucleus?

In mitosis, microtubules are assembled inside the nucleus to form the mitotic spindle that segregates the chromosomes and divide the nucleus. The interphase microtubules are responsible for positioning the nucleus at the middle of the cell. The bundles are attached to the outside of the nuclear envelope.

How do microtubules grow?

Microtubules grow through the addition of tubulin dimers at their tips. One reason is the multistranded structure of the microtubule. Unlike actin, which consists of two helical strands, microtubules are typically formed by 13 protofilaments that can grow independently from each other.

Where do the microtubules of the spindle originate during mitosis?

The microtubules of the spindle originate from the centrioles of the cell.

How are microtubules organized in the cell?

An array of microtubules can arrange themselves in a pinwheel structure to form the basal bodies, which can lead to the formation of microtubule arrays in the cytoplasm or the 9+2 axoneme. Other arrangements range from fungi spindle pole bodies to the eukaryotic chromosomal kinetochores (flat, laminated plaques).

Which direction do microtubules grow?

Microtubule nucleation Microtubules (MT) are polymers on an equilibrium state with their subunit elements, α and β -tubulin, which form dimers and are the building blocks of microtubules. Microtubule polymerization is a regulated process and has a direction: growth occurs towards the plus end of the microtubule.

Where do the microtubules of the spindle apparatus originate during mitosis in both plant and animal cells?

Mitotic spindles are microtubule-based structures that separate chromosomes during mitosis. In most animals and fungal cells, spindle microtubules nucleate from centrosomes or spindle pole bodies.

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells a centromere B centrosome C Centriole D chromatid e kinetochore?

The two separate poles where the microtubules extend from are called the centrosomes, which are formed through the duplication of a single centrosome. They are responsible for the organization of the spindle microtubules. Therefore, the answer is A. centrosome.

Where do microtubules attach to chromosomes?

Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores. Kinetochores are protein formations that develop on each chromosome around the centromere, which is a region located near the middle of a chromosome.

Why must microtubules assemble and disassemble?

In plant cells, microtubules assemble and disassemble during the cell cycle to organize different microtubule arrays. Since the four different microtubule arrays have distinct features and structures, use of different proteins (tubulin and non-tubulin) is a critical requisite for the assembly of each array.

Where do microtubules of the spindle originate?

centrioles
The microtubules of the spindle originate from the centrioles of the cell.