BIOL 1081 Lecture Notes - Lecture 8: Pinocytosis, Exocytosis, Phagocytosis
Ch. 5 LO- 1 Thursday
Membrane structure & function Reading: Sections 5.1-5.6 in textbook
1. Describe the fluid mosaic model, relating both the fluid and the osai parts of the model to
membrane structure and behavior.
• Fluid Mosaic Model
o A mosaic of protein floats in or on the fluid lipid bilayer like boats on a pond
o Mosaic- refers to integral membrane and peripheral proteins
o Fluid-phospholipids manipulate themselves, cholesterol inserts itself, can rearrange
themselves
• Since phospholipid are not corked together, they have relatively free mobility
• Mosaic because structure of bilayer with phospholipid heads and tails
2. Identify how and why membrane fluidity is modified by organisms living in different environments.
• Membrane fluidity a e altered y hagig the erae’s lipid opositio
• Saturated or mono cis-unsaturated tend to make the membrane less fluid as they pack well
• Sphingolipids- unsaturated, make membrane less fluid
• Double bonds- at colder temperatures, introduced by fatty acid desaturase make the membrane
more fluid, counteracting the environmental effect of reduced temperature
3. Describe the types of proteins commonly found in cell membranes, their arrangement in the membrane,
and their functions.
• Transmembrane Proteins:
o Carriers
▪ Actively or passively transport molecules across membrane
o Channels
▪ Passively transport molecules across membrane
▪ Create a selective tunnel that acts as a passage through membrane
o Receptors
▪ Transmit information into cell
▪ Signal molecules bind cell-surface portion of the receptor proteins. This alters the
portion of the receptor proteins within the cell
• Interior Protein Network
o Spectrins
▪ Determine shape of cell
▪ Form supporting scaffold beneath membrane, anchored to both membrane and
cytoskeleton
o Cathrins
▪ Anchor certain proteins to specific sites, especially on the exterior plasma
membrane in receptor mediated endocytosis
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