The animal cell

The rockin rat By The rockin rat, 6th Dec 2013 | Follow this author | RSS Feed
Posted in Wikinut>Guides>Science>Biology>Cells

Discusses the various organelles present in an animal cell and briefly discusses what they are used for


The animal cell is a hugely common structure present in all the huge diversity of animal life around the globe therefore it does not seem unreasonable to understand how such a fundamental piece of life can function to produce amazing overall effects to the lives of the organisms which have them.
An animal cell has 3 basic fundamental parts known as the cell membrane, the cytoplasm ( sometimes called cytosol and the nucleus.
The cell membrane controls the entry and exit of various substances to the cell sometimes through active and sometimes through passive processes. A process known as diffusion primarily works for small non polar molecules in order for them to cross this membrane and it works like this. Substances have a natural goal of flowing from a region where there are a lot of them to a region where there are not as many. The best way to understand it is this. If you had a load of balls on one half of a container crashing into each other it is only a matter if time before some of these approach the opposite side of the container. This process in the human and animal body can be highly exploited to allow important substances to move in and out of cells.
Small non polar molecules move by this natural flow known as diffusion to produce an overall flow down a concentration gradient ( area where there is a lot of substance) to a region where there is not as much of a substance. The area that has a lot can be called the hypertonic region and the area where there is not as many substance particles can be referred to as the hypotonic region.
For larger molecules such as amino acids to enter the cell they need to use special channels as they are too big to fit between the molecules that compose the cell membrane.
These molecules are called phospholipids and are given structure by a molecule with 4 carbon rings known as cholesterol. As a result of this the big molecules must use intrinsic membrane proteins to get from one side of the membrane to the other . Intrinsic generally means on the inside of something but for membranes an intrinsic protein is one that goes the whole way across the membrane. These proteins prevent interaction between the molecule and the fatty acid tails of the phospholipids.
A small charged molecule can use carrier proteins to get from inside to outside or vice versa some of which are controlled by ATP binding.
If the molecule is complementary to a channel which is a passive transporter it can use this to get from one side of the membrane to the other if not it can slot into an active transporter and provided there is enough ATP present can use this to get across the membrane.
These carrier proteins work by changing their shape following the binding of a molecule in a way that is known as a conformational change.
Once in the molecule can participate in various chemical reactions depending on it's chemical constituent atoms.
Most of these chemical reactions take place in the cytoplasm or cytosol.
The nucleus is a region that appears darker under a microscope as a result of trapping stain more readily due to it's high density and is commonly known as the control centre of the cell.
It is where the majority of the genetic information containing coding for proteins can be found and can regulate the general functions of the cell including the rate of enzyme controlled reactions. The osmotic potential or how hypo or hyper tonic the cell cytosol is and can control the degradation of harmful substances. The method used for all these fascinating processes is not always overly clear.
For the most part these functions can be regulated by a chain of events leading to the production of a specialised protein. The start of the chain occurs in the nucleus with a specific type of coding molecule known as m RNA.
m RNA is messenger ribose nucleic acid and is so called because it is made up of subunits known as monomers which are comprised of a type of sugar known as ribose a phosphate atom and a nucleotide base either adenine, uracil, guanine or cytosine.
So overall the main functions of the cell can be regulated by key features of the cell including the main 3 as discussed above giving rise to a huge volume of other molecules that are required for the cell to regulate it's own activity. The cell membrane with it's ability to control what comes in and out of the cell, the nucleus to regulate the overall cell functioning and the cytosol to host the majority of the chemical reactions of the cell. Many of which in unique environments known as organelles.

moderator Steve Kinsman moderated this page.
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