how do receptor proteins help in endocytosis? please answer in easy language.
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Bulk transport
Bulk transport
Endocytosis and exocytosis. Phagocytosis, pinocytosis, and receptor-mediated endocytosis.
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Introduction
Imagine you are a macrophage: a merciless white blood cell that stalks, amoeba-like, through the tissues of the body, looking for pathogens, dead and dying cells, and other undesirables. When you encounter one of these, your task is not just to destroy it, but to devour it whole. (Chomp!)
This complete annihilation may seem a bit over the top, but it serves two useful purposes. First, it recovers valuable macromolecules for the body’s use. Second, in the case of foreign pathogens, it allows the macrophage to present fragments of the pathogen on its surface. This display alerts other immune cells that the pathogen is present and triggers an immune response.
Let’s take a step back, though. How does a macrophage “eat” a pathogen or a piece of cellular debris? In the past few sections, we’ve talked about ways that ions and small molecules, such as sugars and amino acids, can enter and exit the cell via channels and transporters. Channels and carrier proteins are great for letting specific small molecules cross the membrane, but they are too small (and too picky about what they transport) to let a cell take up something like an entire bacterium.
Instead, cells need bulk transport mechanisms, in which large particles (or large quantities of smaller particles) are moved across the cell membrane. These mechanisms involve enclosing the substances to be transported in their own small globes of membrane, which can then bud from or fuse with the membrane to move the substance across. For instance, a macrophage engulfs its pathogen dinner by extending membrane "arms" around it and enclosing it in a sphere of membrane called a food vacuole (where it is later digested).
Macrophages provide a dramatic example of bulk transport, and the majority of cells in your body don’t engulf whole microorganisms. However, most cells do have bulk transport mechanisms of some kind. These mechanisms allow cells to obtain nutrients from the environment, selectively “grab” certain particles out of the extracellular fluid, or release signaling molecules to communicate with neighbors. Like the active transportprocesses that move ions and small molecules via carrier proteins, bulk transport is an energy-requiring (and, in fact, energy-intensive) process.
Here, we’ll look at the different modes of bulk transport: phagocytosis, pinocytosis, receptor-mediated endocytosis, and exocytosis.
Endocytosis
Endocytosis (endo = internal, cytosis = transport mechanism) is a general term for the various types of active transport that move particles into a cell by enclosing them in vesicle made out of plasma membrane.
There are variations of endocytosis, but all follow the same basic process. First, the plasma membrane of the cell invaginates (folds inward), forming a pocket around the target particle or particles. The pocket then pinches off with the help of specialized proteins, leaving the particle trapped in in a newly created vesicle or vacuole inside the cell.
Endocytosis can be further subdivided into the following categories: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
PLEASE MARK IT BRAINLIEST
Bulk transport
Bulk transport
Endocytosis and exocytosis. Phagocytosis, pinocytosis, and receptor-mediated endocytosis.
Google ClassroomFacebookTwitter
Introduction
Imagine you are a macrophage: a merciless white blood cell that stalks, amoeba-like, through the tissues of the body, looking for pathogens, dead and dying cells, and other undesirables. When you encounter one of these, your task is not just to destroy it, but to devour it whole. (Chomp!)
This complete annihilation may seem a bit over the top, but it serves two useful purposes. First, it recovers valuable macromolecules for the body’s use. Second, in the case of foreign pathogens, it allows the macrophage to present fragments of the pathogen on its surface. This display alerts other immune cells that the pathogen is present and triggers an immune response.
Let’s take a step back, though. How does a macrophage “eat” a pathogen or a piece of cellular debris? In the past few sections, we’ve talked about ways that ions and small molecules, such as sugars and amino acids, can enter and exit the cell via channels and transporters. Channels and carrier proteins are great for letting specific small molecules cross the membrane, but they are too small (and too picky about what they transport) to let a cell take up something like an entire bacterium.
Instead, cells need bulk transport mechanisms, in which large particles (or large quantities of smaller particles) are moved across the cell membrane. These mechanisms involve enclosing the substances to be transported in their own small globes of membrane, which can then bud from or fuse with the membrane to move the substance across. For instance, a macrophage engulfs its pathogen dinner by extending membrane "arms" around it and enclosing it in a sphere of membrane called a food vacuole (where it is later digested).
Macrophages provide a dramatic example of bulk transport, and the majority of cells in your body don’t engulf whole microorganisms. However, most cells do have bulk transport mechanisms of some kind. These mechanisms allow cells to obtain nutrients from the environment, selectively “grab” certain particles out of the extracellular fluid, or release signaling molecules to communicate with neighbors. Like the active transportprocesses that move ions and small molecules via carrier proteins, bulk transport is an energy-requiring (and, in fact, energy-intensive) process.
Here, we’ll look at the different modes of bulk transport: phagocytosis, pinocytosis, receptor-mediated endocytosis, and exocytosis.
Endocytosis
Endocytosis (endo = internal, cytosis = transport mechanism) is a general term for the various types of active transport that move particles into a cell by enclosing them in vesicle made out of plasma membrane.
There are variations of endocytosis, but all follow the same basic process. First, the plasma membrane of the cell invaginates (folds inward), forming a pocket around the target particle or particles. The pocket then pinches off with the help of specialized proteins, leaving the particle trapped in in a newly created vesicle or vacuole inside the cell.
Endocytosis can be further subdivided into the following categories: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
PLEASE MARK IT BRAINLIEST
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