Having learned about the what’s, why’s and how’s of the bulk transport namely endocytosis and exocytosis, write a 10 sentences paragraph expressing what do you think will happen if there is no bulk transport in our body.
Answers
Explanation:
Immunology & Microbiology
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Endocytosis and Exocytosis: Differences and Similarities
ARTICLE Apr 28, 2020
by Nicole Gleichmann
Endocytosis and Exocytosis: Differences and Similarities
Endocytosis and exocytosis are the processes by which cells move materials into or out of the cell that are too large to directly pass through the lipid bilayer of the cell membrane. Large molecules, microorganisms and waste products are some of the substances moved through the cell membrane via exocytosis and endocytosis.
Why is bulk transport important for cells?
Cell membranes are semi-permeable, meaning they allow certain small molecules and ions to passively diffuse through them. Other small molecules are able to make their way into or out of the cell through carrier proteins or channels.
But there are materials that are too large to pass through the cell membrane using these methods. There are times when a cell will need to engulf a bacterium or release a hormone. It is during these instances that bulk transport mechanisms are needed.
Endocytosis and exocytosis are the bulk transport mechanisms used in eukaryotes. As these transport processes require energy, they are known as active transport processes.
Vesicle function in endocytosis and exocytosis
During bulk transport, larger substances or large packages of small molecules are transported through the cell membrane, also known as the plasma membrane, by way of vesicles – think of vesicles as little membrane sacs that can fuse with the cell membrane.
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.
What is endocytosis? Endocytosis definition and purposes
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:
Taking in nutrients for cellular growth, function and repair: Cells need materials like proteins and lipids to function.
Capturing pathogens or other unknown substances that may endanger the organism: When pathogens like bacteria are identified by the immune system, they are engulfed by immune cells to be destroyed.
Disposing of old or damaged cells: Cells must be safely disposed of when they stop functioning properly to prevent damage to other cells. These cells are eliminated through endocytosis.
Types of endocytosis
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. These white blood cells are responsible for clearing out aged and damaged cells, as well as disposing of infectious microorganisms.
Pinocytosis
Pinocytosis, also known as cell drinking, is common in plant and animal cells. During pinocytosis, the cell takes in substances from the extracellular fluid that it needs to function. These include things like water and nutrients.
Receptor-mediated endocytosis is a specialized type of pinocytosis. During receptor-mediated endocytosis, macromolecules bind to receptors along the surface of the cell’s plasma membrane. Cholesterol uptake is an example of receptor-mediated endocytosis.