• Submitted By: irinatempel
  • Date Submitted: 10/10/2008 6:44 AM
  • Category: Science
  • Words: 753
  • Page: 4
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The cytoskeleton......
Based on the arrangement of this cytoskeleton. Some filaments (microtubule) allow for movement along them. They are like railroad tracks that are traveled by motor proteins carrying cargo. Cargo could be a membrane bound vesicle despined for delivery at another organelle or it could be a protein. Microtubule allow for a efficient movement between 2 compartments. Proteins that make up the cytoskeleton can also help to “weld” two cells together in a structure known as a desmosome. Often filament can join to make “tight junctions” that do not allow substance to seep between cells into the intercellular space. Cells that are in contact can also be in communication with one another through channels or pores known as “gap functions”. A filaments line these channels. Allow for rapid communication between neighboring cells as molecules and icon can travel from cell to cell without crossing the plasma membrane.

Can plant cells communicate with neighboring cells via channels? Yes they have plasmodesmata where there is neither plasma membrane nor a cell wall.

A cell must be able to communicate with its environment. Communication and exchange occur via the plasma membrane. There is a need to maintain a high rate of exchange to so cell size is limited by this need. Larger organisms generally have more cells not
larger and larger cells.

Prokaryotes- lack membrane bound organelles functionally distinct compartments

Eukoryotes- have membrane bound organelles where different processes occur. The interior of these organelles are suited to the functions of the organelles. we can maintain the environments as distinct from the cytosol because each compartment is surrounded by a restrictive barrier.

Nucleus houses the DNA and is the place of RNA synthesis (rrna, trna ,mrna). The nucleus is surrounded by double membrane (2 phospholipid bilayers) but is studded with a - 3000-4000 pores through which proteins, r nucleic acid and ions can...

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