1. The building blocks of life
Cells
Chapter 3
Cell Organelles (Plasma Membrane, Phospholipid Bilayer, Proteins) Slide 68-78
The building blocks of life

2. Cell membrane how it works (easy way)

3. Biology 1, Lecture 7: Cellular Membranes

4. Membrane Proteins and Their Functions
A membrane is a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer
Proteins determine most of the membrane’s specific functions

5. The Phospholipid Bilayer
In animal cells, the cholesterol molecules that are interspersed between phospholipid molecules in the plasma membrane perform two functions:
They act as a patching material that helps keep some small molecules from moving through the membrane.
They keep the membrane at an optimal level of fluidity.

6. Plasma Membrane Proteins
Some plasma membrane proteins are integral, meaning they are bound to the hydrophobic interior of the phospholipid bilayer.
Others are peripheral, meaning they lie on either side of the membrane but are not bound to its hydrophobic interior.

7. Cell membrane proteins | Cells | MCAT | Khan Academy

8. Membrane Protein Functions
In animal cells, the cholesterol molecules that are interspersed between phospholipid molecules in the plasma membrane perform two functions:
structural support
cell identification, by serving as external recognition proteins that interact with immune system cells
communication, by serving as external receptors for signaling molecules
transport, by providing channels for the movement of compounds into and out of the cell

9. Membrane Protein Functions
Six major functions of membrane proteins
Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix (ECM)

10. Types of Proteins
1) Enzymes – catalyzes covalent bond breakage or formation
2) Structural – collagen, elastin, keratin, etc.
3) Motility – actin, myosin, tubulin, etc.
4) Regulatory – bind to DNA to switch genes on or off
5) Storage – ovalbumin, casein, etc.
6) Hormonal – insulin, nerve growth factor (NGF), etc.
7) Receptors – hormone and neurotransmitter receptors
8) Transport – carries small molecules or irons
9) Special purpose proteins – green fluorescent protein, etc.

11. The Plasma Membrane (a) Structural support (b) Recognition (c)
Communication
(d)
Transport
Membrane proteins can provide structural
support, often when
attached to parts of the cell’s scaffolding or “cytoskeleton.”
Binding sites on some proteins can serve to identify the cell to other cells, such as those of the immune system.
Receptor proteins,
protruding out from the
plasma membrane, can
be the point of contact
for signals sent to the
cell via traveling
molecules, such as
hormones.
Proteins can serve
as channels
through which
materials can pass
in and out of
the cell.
Figure 5.3

12. (b) Enzymatic activity (c) Signal transduction
Figure 7.10
Signaling molecule
Enzymes
Receptor
ATP
Figure 7.10 Some functions of membrane proteins.
(a) Transport
(b) Enzymatic activity
(c) Signal transduction
Glyco- protein
(f) Attachment to the cytoskeleton and extracellular matrix (ECM)
(d) Cell-cell recognition
(e) Intercellular joining 12