Short Explanation of the cell

As we all know the cell is the most important building block of live. It is really tiny and it is impossible to see with just the eye. As you may imagine the cell needs a barrier, a protection and it is called: Cell Membrane. The cell membrane has various functions one of them is to control what comes in and out of the cell. It is also a barrier that sorrounds the cytoplasm and the organells of the cell.

Functions of The Cell Membrane!

The purpose of the membrane is to control what goes in and out of the cell. The items that go in are highly regulated. It also communicates with other cells for example with receptors on the surface or cell to cell union. Proteins that are found in the bilayer are receptor proteins, which deal with communication, recognition proteins and transport proteins that regulate the movement of water and soluble molecules through the membrane. In order to regulate the transport of molecules, there are two types of proteins in the cell: carrier proteins and transport proteins. The two types of transport proteins are channel and carrier protein. Transport is either active or passive. Active transport is moving molecules against the concentration gradient and energy is required in the form of ATP. Passive transport is moving molecules down the concentration gradient and no energy is required. Examples of passive transport are diffusion, which moves from high concentration to low concentration and osmosis, which is the diffusion of water molecules. Finally, the cell membrane is important for the connections between cells. There are four different types of these connections. Desmosomes attach cells together like "glue". A tight junction consists of fusing the cells together. A gap junction consists of pairs of channels fused. Finally, plasmodesma consists of binding plants together.

The Cell Membrane is also called the plasma membrane. It's the external limiting membrane of a cell. It is composed of lipids (fat molecules) that have a hydrophobic (insoluble in water) end and a hydrophilic (water-soluble) end. Cell membranes are made of lipid bilayers in which the lipids line up in two layers with the hydrophobic ends facing each other and the hydrophilic ends facing the outside and the inside of the cell.

Lipids: is another word for "fats.") Lipids can be defined as substances such as a fat, oil or wax that dissolves in alcohol but not in water. Lipids contain carbon, hydrogen and oxygen but have far less oxygen proportionally than carbohydrates. Lipids are an important part of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells.The cell membrane is made up of a lipid bilayer. Cell membranes are also described as lipid bilayers. There are two layers of phospholipids with proteins embedded in the layers. The membrane is able to move as needed by the cell. The head end of a phospholipid molecule is hydrophilic. The heads like to be near water and arrange themselves so that tails meet tails and the heads face the cellular fluids and exterior of the cell. Phospholipids:The tail end of a phospholipid molecule is hydrophobic. The tails do not like to be near water and arrange themselves so that tails meet tails and the heads face the cellular fluids and exterior of the cell.

Hydrophobic: Having a strong aversion for water. Hydrophobic molecules are relatively insoluble in water and tend to sorb to soil particles.

Hydrophillic: a water lover; like a sponge. Hydrophilic molecules tend to interact with water and with each other. Hydrophobic molecules avoid interaction with water and tend to interact with other hydrophobic molecules.

Membrane Structure

Membrane components may:
*be protective
*regulate transport in and out of cell or subcellular
*domain allow selective receptivity and signal transduction by providing transmembrane receptors that bind signaling molecules
*allow cell recognition
*provide anchoring sites for cytoskeletal filaments or components of the extracellular matrix. This allows the cell to maintain its shape and perhaps move to distant sites.
*help compartmentalize subcellular domains or microdomains
*provide a stable site for the binding and catalysis of enzymes.
*regulate the fusion of the membrane with other membranes in the cell via specialized junctions )
*provide a passageway across the membrane for certain molecules, such as in gap junctions.
*allow directed cell or organelle motility

(information taken from the web page: http://cellbio.utmb.edu/cellbio/membrane.htm)

A Comparison with the Great Wall

We may compare the great wall located in China with the cell membrane; now that it has the same function to control the entrance and exitis of things, and also to protect the cell or the country.

Hello And Welcome!

Hello there and welcome to my blog! This blog is an assignment of my science class of the seventh grade in the school Gimnasio la Colina. During these past two periods we, seventh graders, have a studied several topics related to science such as: fossils, minerals, rocks, atoms, chemical equations, ecosystems, echolocations and some other interesting things. In my school the, school year is divided into three parts called periods; the first, the second and the third and last period. In this moment we are in the last and third period, and the science teacher is teaching us the: Cell Membrane. My duty as a seventh grade student is to create a blog in which I can explain all visitors what the cell membrane is, and of course it would be in a really interesting way, so I hope you like my work.