Endocytosis and exocytosis

//Endocytosis and exocytosis

At the cellular level, our body is an extremely busy place. Our cells creates energy, secrete chemicals, expels waste and many, many other functions along with them. Two important key functions in which our cells keep engaged are exocytosis and endocytosis.

 

The definition of endocytosis and exocytosis are as follows:
Exocytosis ‘“ the process through which a cell expels molecules and other large objects that are too large to pass through the cellular membrane
Endocytosis ‘“ a process by which a cell takes in molecules and also other larger objects that are too large to pass through the cellular membrane

The basic or root mechanism by which a cell carries out exocytosis or endocytosis is almost the same. Both makes use of the vesicles for their molecular transport. Vesicles are very small, membrane-enclosed sacs that moves around a cell. They are generally used for the storage and transport purpose. Because they are entirely enclosed by a separate membrane, inside that, they can have a completely different composition than that of their cell.

endocytosis


 Endocytosis by LadyofHats

 

It occurs by an in folding or extension of the plasma membrane to form vesicles or vacuoles.It is divided into two types:

  • Phagocytosis(cell eating):Substances are taken up in solid form.Cells involving this process are called phagocytes.Eg. white blood cells.A phagocytic vacuole is formed during the uptake.
  • Pinocytosis (cell drinking):Substances are taken up in liquid form.Vesicles are formed during intake.It is often associated with amoeboid protozoans and in certain kidney cells involved in fluid exchange.Also occurs in plant cells.

Exocytosis:

exocytosis

                                                                               Exocytosis by LadyofHats

 

 It is the reverse of endocytosis by which materials are removed from cells such as undigested remains from food vacuoles.

 

 

How are vesicles used for endocytosis and exocytosis?
Exocytosis ‘“Wastes or some other chemicals inside cells are surrounded by the vesicle. Sometimes this vesicle is able to draw the molecule through its membrane. Other times it surrounds the molecule and then just ‘swallows’ it. After then the vesicle moves to the edge of cell and then tethers itself to the cellular membrane. After then it pushes its molecular cargo out through the cellular membrane.
Endocytosis ‘“The cell engulfs molecules or proteins in Endocytosis, near the surface of cellular membrane. It can swallow small bits of protein, large molecules, or also create receptor pockets to which a specific types of molecules get attracted. Once the targeted molecule is surrounded by its cellular membrane, the corresponding area is pinched off to create there a vesicle inside the cell which holds the molecule.

One might say from above conclusion that endocytosis creates vesicles and on other hand exocytosis uses and it can potentially destroy vesicles.

Exocytosis is used for the listed following purposes:

  • Release enzymes, proteins, hormones, and glucose for using them in other parts of the body
  • Neurotransmitters (in case of neurons)
  • Communicates defense measures against a disease, if happens
  • Expels cellular waste

Endocytosis is used for listed following purposes:

  • Receiving nutrients
  • Entry of pathogens
  • Cell migration and adhesion
  • Signal receptors

 

We can summarize this in below mentioned concrete points:

 

  • Active transport is energy-requiring process of the pumping molecules and ions across membranes against a concentration gradient.
  • Endocytosis is the process of capturing any substance or particle which is outside the cell by engulfing it with the cell membrane, and then bringing it into the corresponding cell.
  • Exocytosis describes process of the vesicles fusing with plasma membrane and then releasing their contents to the outside of cell.
  • Both exocytosis and endocytosis are active transport processes.
  • The primary function of the endocytosis is getting nutrients and primary function of exocytosis is to expel waste.

 

For remembering the main key differences, we have listed them as followings:

ExocytosisEndocytosis
Exocytosis results is expelling molecules outside of the cell.It helps to ingest molecules towards inside of the cell
This process leads to the destruction of the vesicles.This process leads to the creation of vesicles.
There is a discharge of the enzymes, proteins, hormones and glucose. All these constituents are used for functioning of other body parts.By this process, food particles, nutrients, and proteins are received by body cells. Apart from this, some of the bacteria and pathogens can also get entry into the body by this process.
Example 1: Neurotransmitters released from neuron cells.Example 1: The body cells engulf pathogens and then destroys them.
Example 2: In case of any infection, the cells communicate among themselves, and they strengthen the immune system of infected body by the process of exocytosis.Example 2: Endocytosis is used in the case of cell migration and adhesion related functions.
This process helps in expelling the wastes from the body.This process serves as signal receptor.
By | 2015-08-23T15:26:09+00:00 December 27th, 2012|Bulk transport through membranes|0 Comments

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