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Proteins

Amino Acid Chain

There are hundreds of types of proteins in the cell, each with its own function and physical structure. Proteins are considered the molecular "workers" of the cell because they are present in all areas and processes of the cell. Among the many different roles that proteins serve in the cell, proteins have structural roles to help the cell keep its shape, regulatory roles to control movement of particles in and out of the cell, and repair roles to help signal and and help with repair of a cell if it is damaged. Proteins are especially important in cell division because they control when it starts, ends, and every movement in between.

Below are some common proteins involved in cell division and listed are the roles they play. They may have complicated names, but their functions are essential to the survival and successful division of the cell:

Microtubules: Microtubules are tube-like structural proteins that help chromosomes move throughout the cell. They are "modular" proteins because microtubules can add or subtract protein units to become longer or shorter, respectively, while continuing to provide the cell with structural support during cell division.




Centriole: Centrioles organize microtubules so that some stretch the length of the cell and push the dividing cells away from each other, while other microtubules direct genetic material into each of the cells. Centrioles control many other cellular components and determine the spatial organization and arrangement of the cell.


Kinetochore: Kinetochores are the protein structures located at the intersection of the two sister chromatids that serves as an attachment site for microtubules and spindle fibers during cell division to help pull the two chromatids apart.


Histone: Histones are the proteins that help chromatin to condense. They serve as "spools" around which DNA winds, and play a role in gene regulation. Without histones, the unwound DNA in chromosomes would be very long and unable to fit into the nucleus of a cell.

Microtubule Structure

Centriole Structure

Kinetochore Diagram

Histones

To better visualize the roles of microtubules, centrioles, and kinetochores in the cell, look back at the images depicting the steps of Mitosis on the "What is Cancer?" page.

It makes sense that cancer research involves specific focus on the proteins whose functions are changed in cancerous cells.

Once researchers know to narrow their focus to proteins, how do they study each protein's specific role?

The answer: CHANGE THEM!

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