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1. C E L L
M E M B R A N E
~ A N J U M P E RV E Z

2. CELL MEMBRANE/ PLASMA MEMBRANE
• 1. Outer covering in cells
• 2. Separates and protects the cell from the external environment

3. CHEMICAL COMPOSITION

5. COMPOSITION
1. LIPIDS- phospholipids(abundant,
sphingolipids, glycolipids, sterols(cholesterol)
AMPHIPATHIC
Phospholipids- phosphatidylcholine (lecithin)
and phosphatidylethanolamine (cephalin)
2.PROTEINS
3.CARBOHYDRATES

8. PROTEINS
• 1. Integral proteins
• 2. Peripheral proteins

12. Integral
membrane
proteins have
important
functions in cell
metabolism,
regulation, and
integration.
• Pumps serve to transport certain ions, such as Na, also
metabolic precursors of macromolecules, such as amino
acids and sugars, actively across membranes.
• Channels allow the passage of small ions, molecules, and
• water across the plasma membrane in either direction
(i.e., passive diffusion).
• Receptor proteins allow recognition and localized binding
of ligands in processes such as hormonal stimulation,
coated-vesicle endocytosis, and antibody reactions.
• Linker proteins anchor the intracellular cytoskeleton to the
extracellular matrix.
• Enzymes have a variety of roles.
• Structural proteins form junctions with neighboring cells.

13. CARBOHYDRATES
• Present in plasma membrane
• Present as short, unbranched chains or branched chains of
sugars (oligosaccharides)
• They are attached to either proteins- GLYCOPROTEINS
• OR LIPIDS- GLYCOLIPIDS
• Oligosaccharides- D-galactose, D-mannose, L-fucose, N-
acetylneuraminic acid (also called sialic acid), N-acetyl-D-
glucosamine and N-acetyl-D-galactosamine.

15. FLUID MOSAIC MODEL (Singer and
Nicholson,1972)
• Main components:
• 1. Phospholipids
• 2. Cholesterol
• 3. Proteins
• 4. Chains of oligosaccharides

16. FLUID MOSAIC MODEL (Singer and
Nicholson,1972)

17. FUNCTION
1. Integrity of the cell:
size and shape
2. Controls transport:
selectively permeable
3. Excludes: unwanted
material from entering the
cell
4. Forms a physical
barrier with external
environment
5. Allows the cell to create
different environments
outside and inside.
6. Maintains the ionic
concentration of the cell
and osmotic concentration
of the cytosol
7. Forms contact with
neighboring cells.
8. Sensitivity- first part of
the cell that is affected by
changes in the external
environment.

18. Types of
Transport
Across Cell
Membrane
• 1. Passive transport
• a. Diffusion
• b. Facilitated diffusion
• c. Osmosis
• 2. Active transport
• a. Sodium-potassium pump
• 3. Vesicular transport
• a. Endocytosis
• b. Receptor mediated endocytosis
• c. Phagocytosis
• d. Pinocytosis

19. Types of Transport Across Cell Membrane

20. VESICULAR TRANSPORT

21. ENDOCYTOSIS

22. Phagocytosis
Used to engulf large particles such as food,
bacteria, etc. into vesicles
Called “Cell Eating”

23. Phagocytosis - Capture of a Yeast Cell (yellow) by
Membrane Extensions of an Immune System Cell
(blue)

24. PINOCYTOSIS
Most common form of endocytosis.
Takes in dissolved molecules as a vesicle.

25. Receptor-Mediated Endocytosis
Some integral proteins have receptors on their surface to
recognize & take in hormones, cholesterol, etc.

26. E X O C Y T O S I S
Molecules are moved out
of the cell by vesicles that
fuse with the plasma
membrane.
This is how many
hormones are secreted
and how nerve cells
communicate with one
another.

28. SIGNAL RECEPTION &TRANSDUCTION

29. SIGNAL RECEPTION &TRANSDUCTION
• 1. Endocrine signalling
• 2. Paracrine signalling
• 3. Synaptic signalling
• 4.Autocrine signalling
• 5. Juxtacrine signalling

30. Signal
Reception &
Transduction
3 important functional classes of Receptors for
hydrophilic signaling molecules:
Channel-linked receptors open upon ligand
binding to allow ion transfer across the membrane.
Enzymatic receptors, in which ligand binding
induces catalytic activity in associated peripheral
proteins.
G-protein–coupled receptors upon ligand binding
change an associated “G protein” that then binds
the guanine nucleotide GTP and is released to
activate other cytoplasmic proteins.

31. Textbook
•2015 Junqueira's Basic
Histology Text and Atlas, 15th
Edition, pages 17-26