Here are the key points from the video on cell membrane and cell transport: 1. The cell membrane is a selectively permeable phospholipid bilayer with embedded proteins. The phospholipids are amphipathic with hydrophilic heads and hydrophobic tails, allowing them to spontaneously form a bilayer. Embedded proteins carry out important functions like transport and signaling. 2. Initially, cell transport can be either passive or active. Passive transport does not require energy expenditure from the cell. It includes diffusion, facilitated diffusion, and osmosis. Active transport requires energy expenditure from the cell in the form of ATP. It includes primary and secondary active transport which use transport proteins to move molecules against a concentration gradient.

1. CELL Membranes

2. 2
Competencies
1. describe the structural components of the cell
membrane- STEM_BIO11/12-Ig-h-11
2. relate the structure and composition of the
cell membrane to its function -
STEM_BIO11/12
-Ig-h-12

3. 3
Activity (10 mins)
Q & A
1. What do you remember about Cell membrane?
Describe the membrane
2. Differentiate Plant and Cell membranes?
3. What are common substances impregnated in Cell
membrane and what are its functions?

4. Cell Membrane (Transport) Notes
Cell Membrane and Cell Wall:
• ALL cells have a cell membrane made of proteins and lipids
Cell
Membrane
lipid bilayer
protein channel
protein pump
Layer 1
Layer 2
• SOME cells have cell membranes and cell walls – ex: plants, fungi
and bacteria
Cell
Membrane
Cell Wall

5. • Plant cells have a cell wall
made of cellulose – that
cellulose is fiber in our diet
• Bacteria and fungi also
have cell walls, but they
do not contain cellulose
• Cell membranes and cell
walls are porous allowing
water, carbon dioxide,
oxygen and nutrients to
pass through easily

6. CO 5

7. 7
Membrane Structure
The fluid mosaic model of membrane
structure has two components:
1. Phospholipids arranged in a bilayer
2. Globular Proteins inserted in the lipid
bilayer

8. 8

9. 9
Membrane Structure
Cellular membranes have 4 components:
1. Phospholipid Bilayer
2. Transmembrane Proteins
3. Interior Protein Network
4. Cell Surface Markers

10. 10

11. 11
Membrane Structure
• Membrane structure is visible using an
electron microscope.
• Transmission electron microscopes (TEM)
can show the 2 layers of a membrane.
• Freeze-fracturing techniques separate the
layers and reveal membrane proteins.

12. Fig. 5.3-1

13. Fig. 5.3-2

14. Fig. 5.3-3

15. Fig. 5.3-4

16. 16

17. 17
1. Phospholipids
Phospholipid Structure (Chapter 3)
-glycerol – a 3-carbon polyalcohol acting
as a backbone for the phospholipid
-2 fatty acids attached to the glycerol
-phosphate group attached to the
glycerol

18. 18
1. Phospholipids
The fatty acids are nonpolar chains of
carbon and hydrogen.
-Their nonpolar nature makes them
hydrophobic (“water-fearing”).
-The phosphate group is polar and
hydrophilic (“water-loving”).

19. 19
1. Phospholipids
The partially hydrophilic, partially
hydrophobic phospholipid
spontaneously forms a bilayer:
-fatty acids are on the inside
-phosphate groups are on both
surfaces of the bilayer

20. 20

21. 21
1. Phospholipids
•Phospholipid bilayers are fluid:
- Hydrogen bonding of water holds the 2
layers together
- Individual phospholipids and unanchored
proteins can move laterally through the
membrane

22. 22
1. Phospholipids
•Phospholipid bilayers are fluid:
- Saturated fatty acids make the membrane
less fluid than unsaturated fatty acids
- Cholesterols make the membrane more rigid
- Warm temperatures make the membrane
more fluid than cold temperatures

23. 87
Fatty Acids

24. 2-83
Lipids: Cholesterol
HO
H3C
CH3
CH3
CH3
CH3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 2.22

25. 25

26. 26
Fluid Mosaic Model

27. 27
2. Membrane Proteins
Membrane proteins have various functions:
1. Transporters
2. Enzymes
3. Cell Surface Receptors
4. Cell Surface Identity Markers
5. Cell-to-Cell Adhesion Proteins
6. Attachments to the Cytoskeleton

28. 28

29. 29
Membrane Proteins
• Two types of membrane proteins
- Classified by how they are associated with
the membrane
1. Peripheral membrane proteins
2. Integral membrane proteins

30. 30
Membrane Proteins
1. Peripheral membrane proteins
• Anchored to a phospholipid in one layer
of the membrane
• on the intracellular or extracellular face of the
membrane
• Possess nonpolar regions that are
inserted in the lipid bilayer
• Free to move throughout one layer of the
bilayer

31. 31
1. Peripheral membrane proteins

32. 32
Membrane Proteins
2. Integral membrane proteins
• Span the lipid bilayer (transmembrane
proteins)
• Nonpolar regions of the protein are
embedded in the interior of the bilayer
- Transmembrane Domain
• Polar regions of the protein protrude from
both sides of the bilayer

33. 33
2. Integral membrane proteins

34. 34
Membrane Proteins
• Integral proteins possess at least one
transmembrane domain
- Region of the protein containing hydrophobic
amino acids
- Spans the lipid bilayer
- Usually alpha-helices
- Many receptors are integral proteins

35. 35

36. 36
Membrane Proteins
• Extensive nonpolar regions within a
transmembrane protein can create a pore
through the membrane.
• sheets in the protein secondary structure
form a cylinder called a -barrel
• -barrel interior is polar and allows water and
small polar molecules to pass through the
membrane

37. 37

38. 38
Membrane Transport
• Motion of substances in and out of the cell
• Cell membranes are Selectively
permeable
• Two Types of Transport Mechanisms:
1. Passive Transport
2. Active Transport

39. 39
Membrane Transport
• Passive transport is movement of
molecules through the membrane in which
no energy is required from the cell
• Active transport requires energy
expenditure by the cell

40. Video on Cell membrane and
Cell Transport
40
Guide Questions:
1. What is cell membrane and its composition
based on the video?
2. Initially, what is Cell Transport? Describe
each type.