What is the difference between endocytosis and exocytosis biology

As these transport processes require energy, they are known as active transport processes. Cell membranes are comprised of a lipid bilayer. The walls of vesicles are also made up of a lipid bilayer, which is why they are capable of fusing with the cell membrane.

This fusion between vesicles and the plasma membrane facilitates bulk transport both into and out of the cell. Endocytosis is the process by which cells take in substances from outside of the cell by engulfing them in a vesicle. These can include things like nutrients to support the cell or pathogens that immune cells engulf and destroy.

Endocytosis occurs when a portion of the cell membrane folds in on itself, encircling extracellular fluid and various molecules or microorganisms. The resulting vesicle breaks off and is transported within the cell.

Endocytosis serves many purposes, including:. There are two types of endocytosis: phagocytosis and pinocytosis. Phagocytosis Phagocytosis, also known as cell eating, is the process by which cells internalize large particles or cells, like damaged cells and bacteria. Within the human body, and in other mammals, phagocytosis is how immune cells engulf and destroy dangerous microorganisms or toxic compounds. Macrophages and neutrophils, types of white blood cells, are the two primary phagocytes.

Endocytosis and Exocytosis Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane. There are two main kinds of endocytosis: Phagocytosis , or cellular eating, occurs when the dissolved materials enter the cell.

The plasma membrane engulfs the solid material, forming a phagocytic vesicle. Pinocytosis , or cellular drinking, occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter the cell, as shown in Figure below. When the channel is closed, the liquid is encircled within a pinocytic vesicle.

Illustration of an axon releasing dopamine by exocytosis. Summary Active transport is the energy-requiring process of pumping molecules and ions across membranes against a concentration gradient. Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane , and bringing it into the cell. Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell.

Both endocytosis and exocytosis are active transport processes. Once these secretory proteins are loaded into secretory vesicles, they undergo post translational modifications like the liberation of active molecules by proteolysis.

The secretion can be activated by extracellular signals as well. This regulated exocytosis is called regulated secretory pathway. Histamine is secreted by mast cells, once a soluble stimulant called the ligand is bound to the receptors on the mast cells surface.

Histamine leads to sneezing and itching, which are accompanied by allergic reactions. Neurotransmitters are also secreted by the regulated secretory pathway. Figure 2: Types of Exocytosis. Endocytosis: Endocytosis is involved in the up taking of substances from the external environment. Exocytosis: Exocytosis is involved in the elimination of waste and secretion of contents in Golgi into the external environment.

Endocytosis: During endocytosis, an endocytic vesicle is formed surrounding the foreign substance, which is either a solid or a liquid. Exocytosis: During exocytosis, the vesicle containing the waste is fused with the plasma membrane in order to eliminate its contents. Endocytosis: Endocytosis occurs by both phagocytosis and pinocytosis. Exocytosis: Exocytosis occurs by constitutive and regulated secretory pathways. Endocytosis: Internal vesicles like phagosomes are formed during endocytosis.

Exocytosis: Secretory vesicles are formed during exocytosis. Endocytosis: Engulfing bacteria by phagocytes is an example for endocytosis.

Exocytosis: Releasing of hormones out of the cell is an example for exocytosis. The movement of macromolecules like proteins and polysaccharides into or out of the cell is known as bulk transport. Two types of bulk transport are identified: exocytosis and endocytosis.

Both these transport methods require energy in the form of ATP. Cells perform three main types of endocytosis. Phagocytosis is the process by which cells ingest large particles, including other cells, by enclosing the particles in an extension of the cell membrane and budding off a new vesicle. During pinocytosis, cells take in molecules such as water from the extracellular fluid. Finally, receptor-mediated endocytosis is a targeted version of endocytosis where receptor proteins in the plasma membrane ensure only specific, targeted substances are brought into the cell.

Exocytosis in many ways is the reverse process from endocytosis. Here cells expel material through the fusion of vesicles with the plasma membrane and subsequent dumping of their content into the extracellular fluid. Answer the question s below to see how well you understand the topics covered in the previous section. This short quiz does not count toward your grade in the class, and you can retake it an unlimited number of times.

Use this quiz to check your understanding and decide whether to 1 study the previous section further or 2 move on to the next section. Privacy Policy. Skip to main content. Module 5: Cell Membranes. Search for:. Endocytosis and Exocytosis Describe the primary mechanisms by which cells import and export macromolecules In addition to moving small ions and molecules through the membrane, cells also need to remove and take in larger molecules and particles.

Learning Objectives Describe endocytosis and identify different varieties of import, including phagocytosis, pinocytosis, and receptor-mediated endocytosis Identify the steps of exocytosis. In Summary: Endocytosis and Exocytosis Cells perform three main types of endocytosis.