Cytoplasm and Cytoskeleton By: Tim Yacoub and Lizette Magdaleno

Cytoskeleton Overview  Cytoskeleton is a “network of fibers that extend[s] throughout the cytoplasm,”(113).  It’s three structures: microtubules, microfilaments, and intermediate filaments  It helps with the organization of activities, cell mobility, and structure of the cell

Cytoskeleton: Microtubules  In all eukaryotic cells, Shape: hallow tubes  Made from protein called tubulin by centrioles  Help shape and support the cell, Compression-resistant, function as roads for mobile organelles to move along.  Aid in chromosome separation in cell division.  Special arrangement of microtubules form flagella and cilia.

Cytoskeleton: Microfilaments  In all eukaryotic cells, Shape: thin solid rods  Made from a globular protein: Actin, (twisted double chain of actin subunits).  Functions as a tension bearer, networks inside the plasma membrane to support cell shape, this layer is called a cortex.  Well known for its aid in cell movement, actin, along with Myosin interact, for example, to contract muscle cells

Cytoskeleton: Intermediate Filaments  Coiled cables, larger than microfilaments but smaller than microtubules  Made of several proteins similar to keratins  Only in some animal cells, bears tension (like microfilaments)  More of a permanent structure within the cytoskeleton  Reinforces shape of cell, and anchors certain organelles within the cytoplasm

Cytoplasm Overview  Cytoplasm is “the contents of the cell bounded by the plasma membrane, in eukaryotes, the portion exclusive of the nucleus.” (G-9)

Cytoplasm: Structure  It is the Fluid where the cellular organelles are suspended.  It fills up all the spaces in the cell that are not being filled by the organelles  3 Residents of Cytoplasm:  1.Cytosol  2.Organelles  3.Cytoplasmic Inclusions

Cytoplasm: Characteristics  Fluid substance that fills the space between the cell membrane and cellular organelles  High percentage of water  It is colloidal  It contains proteins  90% water and 10% organic and inorganic compounds

Cytoplasm: Zones  Plasmogel - peripheral zone of cytoplasm that is thick and jelly- like  Plasmosol - zone is thin and liquefied

Cytoplasm: Function  Site of many biochemical reactions  Place where cell expands and grows  Provides a medium for organelles to remain suspended  Aids in movement of different cellular elements  Break down macromolecules  Transport of genetic material