Cellular Membranes I. General Functions

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Presentation transcript:

Cellular Membranes I. General Functions A. Compartmentalization (rooms) B. Selective Barrier (semi-permeable) Figure 4.4A C. Responder to External Signals (Hello?) Figure 11.10

D. Intra. or Extracellular Interactions (anchoring) Figure 4.19 E. Biochemical Activities (Help with reactions)

F. Energy Transformation (one form to another) G. Transporter (moving across a membrane into or out of a cell))

II. History A. E. Gorter & F. Grendel 1925 B. H. Davson & J. Danielli 1935 C. S. J. Singer & G. Nicholson 1972 Fluid Mosaic Model

D. Evidence (freeze fracture technique)

III. Structural Molecules A. Lipids 2. Cholesterols (rigid) 1. Phospholipids (change choline in head to another molecule and change function of whole molecule) Figure 3.9A Figure 3.9C Figure 4.6

B. Carbohydrates 1. Oligosaccharides (short carbo. chain ending with Sialic acid) Sialic acid Figure 5.1 2. Antigens and Labeling (name tags or binders)

C. Proteins 1. Integral (span the bilayer) a. Domains (sections of a protein)

2. Peripheral (one side of bilayer or the other) Figure 5.1 3. Lipid Anchored (proteins bound to the phospholipids) Inositol (replaces choline to bind to the proteins and anchor them)

A. Issues IV. Fluidity 1. Temperature Figure 4.6

2. Interactions Figure 5.1

V. Mechanisms for Movement A. Passive Transport (Just happens without energy use) 1. Requirements and Forces a. Favorable and with concentration gradient b. Molecular size c. Slight molecular or atomic polarity 2. Mechanisms a. Simple Diffusion (between phospholipids) b. Osmosis (needs a protein channel) (conditions of solute concentration are isotonic, hypotonic, or hypertonic) c. Facilitated Diffusion (needs a protein channel)

Figure 5.3A & B Figure 5.4 Figure 4.6 Figure 5.5 Figure 5.6

B. Active Processes 1. Requirements and Forces a. Needs Energy b. Against concentration gradient c. Protein channel or involves many proteins 2. Mechanisms a. Molecular (moving molecules) b. Bulk = i. Endocytosis vs. ii. Exocytosis (membrane folding) iii. Bulk = Cell-mediated (needs receptors)

Figure 5.8 Figure 5.9 Figure 5.9 Figure 5.9