What is the difference between spindles and microtubules?

They are the same thing. As the others have written, microtubules are a “track” that can move organelles around when “motor” proteins (that cleave ATP) pull those organelles. The spindle is what moves the chromosomes during mitosis and meiosis.

What are the 3 types of spindle microtubules?

The overall shape of the spindle is framed by three types of spindle microtubules: kinetochore microtubules (green), astral microtubules (blue), and interpolar microtubules (red). Microtubules are a polarized structure containing two distinct ends, the fast growing (plus) end and slow growing (minus) end.

How do microtubules elongate?

Spindle microtubules that do not engage the chromosomes are called polar microtubules. These microtubules overlap each other midway between the two poles and contribute to cell elongation. Each chromatid, now called a chromosome, is pulled rapidly toward the centrosome to which its microtubule is attached.

How are microtubules related to spindles?

Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores.

What do kinetochore microtubules do?

Kinetochore microtubules attach the chromosomes to the spindle pole; interpolar microtubules extend from the spindle pole across the equator, almost to the opposite spindle pole; and astral microtubules extend from the spindle pole to the cell membrane. During mitosis, several types of microtubules are active.

What do astral microtubules do?

The function of astral microtubules can be generally considered as determination of cell geometry. They are absolutely required for correct positioning and orientation of the mitotic spindle apparatus, and are thus involved in determining the cell division site based on the geometry and polarity of the cells.

What are the two types of spindle microtubules?

In addition to the kinetochore microtubules, there are two other distinct types of microtubules in the spindle: the polar microtubules (shown in red), which grow out from the centrosomes and have opposing microtubules overlapping at the spindle equator; and the aster microtubules (shown in blue), which grow out from …

Do spindles push or pull?

pombe, spindle movements involve microtubule-pushing forces. At the transition from interphase to mitosis, interphase microtubules are attached to the duplicated spindle pole body.

Why are kinetochore microtubules stable?

These results suggest that stable kinetochore–microtubule attachments in the absence of chromosome bi-orientation generate a rearrangement of kinetochore proteins that produces a small, but significant, displacement of the outer kinetochore from the inner kinetochore.

Are kinetochore microtubules?

Accurate chromosome segregation critically depends on the formation of attachments between microtubule polymers and each sister chromatid. The kinetochore is the macromolecular complex that assembles at the centromere of each chromosome during mitosis and serves as the link between the DNA and the microtubules.

Do kinetochore microtubules Depolymerize?

Kinetochores are end-coupled and pulled poleward as the microtubules depolymerize [12,13].

How many microtubules are there in a spindle?

A study on the number of microtubules has shown that there may be as few as single micro­tubule per chromosome in the spindle of yeast cell and as many as 5000 in the spindle of a higher plant cell. The chromosomal fibres are also called kinetochore tubules.

How are microtubules related to the structure of chromosomes?

Related Biology Terms 1 Tubulin – The protein that makes up microtubules. 2 Cytoplasm – All the contents of a cell except for the nucleus. 3 Spindle apparatus – A structure formed mainly by microtubules that separates chromosomes during mitosis. 4 Kinetochore – A protein complex that helps attach chromosomes to microtubules in the mitotic spindle.

What are the role of nonkinetochore microtubules in mitotic spindles?

These microtubules find and interact with the corresponding nonkinetochore microtubules from the opposite centrosomes to form the mitotic spindles. Nonkinetochore microtubules are responsible for elongating the cell during anaphase. Moreover, nonkinetochore microtubules are charged.

How are spindle fibers attached to the chromosomes?

Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores.

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