BIOL 3.4 Cytoskeleton

Cytoskeleton

A network of protein fibers (actin filaments, intermediate filaments, and microtubules) that holds the cell together, helps the cell to keep its shape, and aids in movement.

Centrosome

A structure, near the nucleus, in the cytoplasm of animal cells that functions a microtubule-organizing center and is important during cell division. A centrosome has two centrioles in animal cells and only one in plant cells.

Identify the structural makeup of actin filaments, intermediate filaments, and microtubules...

All 3 are part of the cytoskeleton. Intermediate filaments have a structural role, while actin and microtubules have a structural and movement role. -Actin is composed of actin monomers. -Microtubules are composed of tubulin monomers. -intermediate is composed of fibrous polypeptides.

spindle apparatus

Before the cell divides, microtubules disassemble and reassemble into this structure that attaches to the chromosomes and ensures they are distributed in an orderly manner; also helps divide the cell in half and once it is split the spindle apparatus disassembles and reassembled into microtubules.

Contrast the function of cilia, flagella, and centrioles...

Centrioles function in the process of cell division, while both cilia and flagella are involved in locomotion.

Microtubules

Hollow cylinders of protein molecules that form a tubelike structure with an empty central core; made of the globular protein tubulin; microtubule assembly is controlled in the microtubule organizing center located in the centrosome; they function as tracks organelles move along and help hold the cell shape together. Used by cilia and flagella

Contrast the functions of the three main types of RNA.

Messenger RNA carries copies of instructions for assembling proteins from DNA to the ribosomes. Ribosomal RNA is a component of the ribosomes. Transfer RNA carries amino acids to the ribosomes for assembly into proteins.

intermediate filaments

Ropelike assemblies of fibrous polypeptides in the cytoskeleton that provide support the nuclear envelope and some support the plasma membrane and take part in cell-to-cell junctions; their size is in between actin and microtubules.

How is cilia and flagella involved in movement?

The dynein sidearms on the microtubule doubles slide past each other using energy of ATP.

actin filaments (microfilaments)

a thin type of protein filament composed of actin proteins that forms part of the cytoskeleton and supports the plasma membrane and plays a key role in cell strength, shape and movement; small fibrils that forms in bundles, sheets or networks in the cytoplasm; yielding muscle contraction; account for the formation of pseudopods (false feet)

cilia and flagella

hairlike structures that move like a whip (flagella) or stiffly like an oar (cilia). Cells that have these organelles are capable of movement.

motor molecules

proteins that can attach, detach, and reattach farther along an actin filament. Ex.in muscles the motor molecule myosin pulls actin filaments along in this way using the energy of ATP.

Centrioles

short cylinders made of microtubules surrounding a hollow center; cylindrical organelle near the nucleus in animal cells, existing in pairs, that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during animal cell division.