LE 3-1
Blood cells
Smooth muscle cell
Bone cell
Ovum
Sperm
Cells lining intestinal tract
Neuron in brain
Fat cell

LE 3-2
Cilia
Cytoplasm
Mitochondrion
Nuclear envelope surrounding nucleus
Secretory vesicles
Plasma (cell) membrane
Chromatin (DNA)

•Form the boundary between the intracellular compartment and the extracellular environment.
•“Traffic Cop” - Regulate what enters and leaves the cell = “selective permeability.”
•Respond to substances that come in contact with the membrane. Ex: insulin, glucagon, & other hormones
•Secrete (=squeeze out) substances that are synthesized inside the cell.
•Compartmentalize and organize the interior of the cell.
Ex: mitochondria, E.R., various vesicles

Early evidence for the bi-layered structure of the plasma membrane came from transmission electron micrographs.
This is the plasma membrane of a RBC.

Here is a detailed picture of the way six phospholipid molecules interact with each other and their surroundings to form a phospholipid bilayer.

Phospholipid Animation
(Click Here)

LE 3-3
EXTRACELLULAR FLUID
Carbohydrate chains
Phospholipid bilayer
Protein with channel
Hydrophobic tails
Proteins
Cell membrane
Protein with gated channel
Cholesterol
Proteins Hydrophilic heads
Cytoskeleton
CYTOPLASM

LE 3-5
EXTRACELLULAR
FLUID
Lipid-soluble molecules, O
2
CO and diffuse through membrane
2 lipids.
Plasma membrane
Channel protein
Large molecules that cannot diffuse through lipids cannot cross the membrane unless they are transported by a carrier mechanism
CYTOPLASM
Small water-soluble molecules and ions diffuse through membrane channels

LE 3-4
Diffusion = spreading of molecules from a place where the concentration [ ] is higher to a place where it’s lower .

2

Gray dots represent
= anything dis solute particles. Solute sol ved in the water.

LE 3-6-1
Two solutions containing different solute concentrations are separated by a selectively permeable membrane.
Water molecules (small blue dots) begin to cross the membrane toward solution B, the solution with the higher concentration of solutes (larger pink circles).
A
Water molecules
Glucose molecules
B
Selectively permeable membrane

LE 3-6-2a
At equilibrium, the solute concentrations on the two sides of the membrane are equal. The volume of solution B has increased at the expense of that of solution A.
Volume decreased
Volume increased

http://www.biologycorner.com/bio1/diffusion.html
http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm
http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf

LE 3-7a
Water molecules

LE 3-7b
Water molecules

LE 3-7c
Solute molecules
Hypertonic

LE 3-8
Glucose molecule attaches to receptor site
EXTRACELLULAR
FLUID
Receptor site
Carrier protein
CYTOPLASM
Change in shape of carrier protein
Glucose released into cytoplasm

LE 3-9
EXTRACELLULAR FLUID
3 Na +
Sodium
– potassium exchange pump
2 K +
ATP
ADP
CYTOPLASM

LE 3-10
EXTRACELLULAR
FLUID
Ligands binding to receptors
Exocytosis
Ligand receptors
CYTOPLASM
Coated vesicle
Ligands
Endocytosis
Ligands removed
Fused vesicle and lysosome
Lysosome

LE 3-11
Cell membrane of phagocytic cell
Lysosomes
Vesicle
Foreign object
Pseudopodium
(cytoplasmic extension)
EXTRACELLULAR FLUID
CYTOPLASM
Undissolved residue

LE 3-12
Microvillus
Microfilaments
Cell membrane
Mitochondrion
Intermediate filaments
Endoplasmic reticulum
Secretory vesicle
Microtubule

LE 3-14a
Endoplasmic reticulum CYTOSOL
Lysosomes
EXTRACELLULAR
FLUID
Cell membrane
Secretory vesicles
Transport vesicle
Golgi apparatus Membrane renewal vesicles
Vesicle incorporation in cell membrane

LE 3-14b
Exocytosis

• http://www.wiley.com/legacy/college/boyer/04
70003790/animations/membrane_transport/me mbrane_transport.htm