Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
Protein targeting or protein sorting is the mechanism by which a cell transports to the appropriate positions in the cell or outside of it. Both in prokaryotes and eukaryotes, newly synthesized proteins must be delivered to a specific sub-cellular location or exported from the cell for correct activity. This phenomenon is called protein targeting. Protein targeting is necessary for proteins that are destined to work outside the cytoplasm.This delivery process is carried out based on information contained in the protein itself. Correct sorting is crucial for the cell; errors can lead to diseases. In 1970, Günter Blobel conducted experiments on the translocation of proteins across membranes. He was awarded the 1999 Nobel Prize for his findings. He discovered that many proteins have a signal sequence, that is, a short amino acid sequence at one end that functions like a postal code for the target organelle.
Describes the plasma membrane in detail, explains the each major component with its functions.
Transport mechanism across the cell is covered with detailed explanation with examples.
by Dr. N.Sivaranjani, MD
Protein targeting or protein sorting is the mechanism by which a cell transports to the appropriate positions in the cell or outside of it. Both in prokaryotes and eukaryotes, newly synthesized proteins must be delivered to a specific sub-cellular location or exported from the cell for correct activity. This phenomenon is called protein targeting. Protein targeting is necessary for proteins that are destined to work outside the cytoplasm.This delivery process is carried out based on information contained in the protein itself. Correct sorting is crucial for the cell; errors can lead to diseases. In 1970, Günter Blobel conducted experiments on the translocation of proteins across membranes. He was awarded the 1999 Nobel Prize for his findings. He discovered that many proteins have a signal sequence, that is, a short amino acid sequence at one end that functions like a postal code for the target organelle.
A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.
More than half of all proteins interact with membranes.
explain the types and the formation of vesicles.for downloading the presentation ,more presentations , infographics and blogs visit :
https://studyscienceblog.wordpress.com
endocytosis and exocytosis is a procss of cell eating and drinnking. it is a mazor tool for self defence to an individual cell. there are some molecular mechanism for this process described in given notes.
A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle.
More than half of all proteins interact with membranes.
explain the types and the formation of vesicles.for downloading the presentation ,more presentations , infographics and blogs visit :
https://studyscienceblog.wordpress.com
endocytosis and exocytosis is a procss of cell eating and drinnking. it is a mazor tool for self defence to an individual cell. there are some molecular mechanism for this process described in given notes.
Phagocytosis and pinocytosis are both processes by which cells take in substances from their environment, but they differ in the types of materials they ingest and the mechanisms involved.
Phagocytosis:
Phagocytosis is a cellular process in which specialized cells, such as macrophages and neutrophils, engulf and digest large particles or microorganisms, such as bacteria, viruses, or cellular debris. It involves the formation of pseudopodia (extensions of the cell membrane) around the target particle, enclosing it within a membrane-bound vesicle called a phagosome. The phagosome then fuses with lysosomes, forming a phagolysosome, where the engulfed material is degraded by enzymes. Phagocytosis plays a critical role in immune defense by clearing pathogens and debris from the body.
Pinocytosis:
Pinocytosis, also known as "cell drinking," is a non-specific cellular process in which cells take in fluid and dissolved substances from their surroundings by invaginating a portion of the cell membrane to form small vesicles called pinocytic vesicles. These vesicles contain the ingested fluid and substances and are internalized into the cell's cytoplasm. Pinocytosis occurs continuously in most cells and is involved in nutrient uptake, regulation of extracellular fluid composition, and sampling the extracellular environment. Unlike phagocytosis, pinocytosis does not involve specific recognition of target molecules and is not limited to particular types of particles.
In summary, phagocytosis is the engulfment and digestion of large particles or microorganisms by specialized cells, whereas pinocytosis is the non-specific uptake of fluid and dissolved substances by cells through invagination of the cell membrane. Both processes are essential for cellular function, nutrient acquisition, and immune defense.
Receptors are the sensing elements in the system of chemical communications that coordinates the function of all the different cells in the body and receptor is a protein molecule, embedded in either the plasma membrane or the cytoplasm of a cell, to which one or more specific kinds of signaling molecules may attach.
Endocytosis is a cellular process in which substances are brought into the cell
It is of three types
1. PHAGOCYTOSIS
2. PINOCYTOSIS
3. RECEPTOR MEDIATED ENDOCYTOSIS
Transport of biomolecules across cell membraneMohan Raj
The diffusion of water through the plasma membrane is of such importance to the cell that it is given a special name: osmosis. This page will examine how ions and small molecules are transported across cell membranes. The transport of macromolecules through membranes is described in Endocytosis.
3. In diffusion, dissolved particles (solutes) move down a
concentration gradient. Sometimes cells need to move
non-dissolved particles, or large amounts of material,
across the cell membrane. They can do this by two
processes: endocytosis and exocytosis.
5. Endocytosis: {Endo (within) cytosis (cell} : The process
by which a cell moves large amounts of material, or
non-dissolved particles, into its cytoplasm from the
outside environment.
Exocytosis: {Exo (exit) cytosis (cell)} : The process by
which large amounts of material, or large non-dissolved
particles, are moved from the cell’s cytoplasm to the
outside environment.
7. Endocytosis is the case when a molecule causes the cell
membrane to bulge inward, forming a vesicle.
The three types of endocytosis are:
Receptor mediated endocytosis
Phagocytosis
Pinocytosis
9. Receptor mediated endocytosis (RME) is the type of
endocytosis. RME is an endocytotic mechanism in
which specific molecules are ingested into the cell. The
specificity results from a receptor-ligand interaction.
The interior portion of the receptors protein is embedded
in the membrane.
The protein Catherin coats the inside of the membrane in
the area of the pit. Receptors on the plasma membrane
of the target tissue will specifically bind to ligands on
the outside of the cell. An endocytotic process occurs
and the ligand is ingested.
10. diagrammatically exPlanation
Ligand binds to membrane receptor.
Clathrin-
coated pit
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to
clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves
to the cell membrane.
Transport vesicle
and cell membrane
fuse (membrane
recycling).
Exocytosis
Clathrin
Endosome
Receptors
and ligands
separate.
Receptor
4
1
2
3
4
9
8
7
6
5
11. Steps Of Receptor Mediated
Endocytosis
Step 1:
Ligand binds to membrane receptor. Extracellular fluid
Intracellular fluid
Receptor
1
16. Step 6
Ligand binds to membrane receptor.
Clathrin-
coated pit
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to
clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Clathrin
Endosome
Receptors
and ligands
separate.
Receptor
4
1
2
3
4
6
5
17. Step 7
Ligand binds to membrane receptor.
Clathrin-
coated pit
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to
clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves
to the cell membrane.
Clathrin
Endosome
Receptors
and ligands
separate.
Receptor
4
1
2
3
4
7
6
5
18. Step 8
Ligand binds to membrane receptor.
Clathrin-
coated pit
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to
clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves
to the cell membrane.
Transport vesicle
and cell membrane
fuse (membrane
recycling).
Clathrin
Endosome
Receptors
and ligands
separate.
Receptor
4
1
2
3
4
8
7
6
5
19. Last Step
Ligand binds to membrane receptor.
Clathrin-
coated pit
Extracellular fluid
Intracellular fluid
To lysosome or
Golgi complex
Receptor-ligand migrates to
clathrin-coated pit.
Endocytosis
Vesicle loses
clathrin coat.
Ligands go to lysosomes
or Golgi for processing.
Transport vesicle
with receptors moves
to the cell membrane.
Transport vesicle
and cell membrane
fuse (membrane
recycling).
Exocytosis
Clathrin
Endosome
Receptors
and ligands
separate.
Receptor
4
1
2
3
4
9
8
7
6
5
20. Uptake of cholesterol
The uptake of cholesterol by mammalian cells has
provided a key model for understanding
receptor-mediated endocytosis at the molecular level.
Cholesterol is transported through the bloodstream in
the form of lipoprotein particles, the most common of
which is called low-density lipoprotein, or LDL
The uptake of LDL by mammalian cells requires the
binding of LDL to a specific cell surface receptor that is
concentrated in clathrin-coated pits and internalized by
endocytosis.
24. Phagocytosis is one type of endocytosis that occurs when
a cell uses its membrane to bring non-dissolved particles
solid particles into its cytoplasm. In phagocytosis, the cell
extends finger-like projections of its cell membrane,
called pseudopods, around a piece of solid material
outside of the cell.
The pseudopods that surround the solid object eventually
join to form a vacuole with in the cells cytoplasm. The
cell then releases chemicals into the vacuole. The
chemicals digest the solid particle into smaller particles
that may be used for energy or building material.
Phagocytosis is also often called “cell eating”.
33. NoN ProfessioNals
Phagocytosis is not their main function , do not
have specific receptors.
Lymphocytes
NK and LGL cells (Large Granular lymphocytes)
Epithelial cells
Endothelial cells
Fibroblasts
34. How does it work?
Entry of the pathogen
Recognition & phagocytosis by tissue
phagocytes
SOS signals
Recruitment of phagocytes & inflammation
37. Pinocytosis is another form of endocytosis in which
small particles are brought into the cell, forming an
invagination and then suspended with in small vesicles
and then it breaks down the particles. Pinocytosis is
also known as “cell drinking”.
Pinocytosis works just like phagocytosis but the only
difference other hand, pinocytosis is when he cell
engulfs already-dissolved or broken-down food.