Topic 1: Cell Biology
1.3 & 1.4 Cellular Membranes
1 – MEMBRANE STRUCTURE
Read & Consider 1.3.1 – 1.3.3
• What do you know?• What questions do you
have?
WaterCells are surrounded by water inside and out. Membrane behavior is dictated by interactions with water.
• Polar• Nonpolar
Phospholipid – what can you deduce?
Draw, label, and annotate the Fluid Mosaic Model – 2D
The diagram should include: Phospholipid bilayer Cholesterol Glycoproteins Integral proteins Peripheral proteins
academic.brooklyn.cuny.edu
Protein & Cholesterol
Discovery
Watch – History of Cell Membrane up to Gorter and Grendel’s 1925 discovery “Insights into cell membranes via dish detergent”
Davson and Danielli’s “Fat Sandwich Model” – accepted until 1972
Singer and Nicolson’s “Fluid Mosaic Model” – accepted today
2 – MEMBRANE TRANSPORTRead & Consider 1.4.1-1.4.2
• What do you know?• What questions do you have?• Compare and contrast diffusion and osmosis.
Diffusion & Osmosis
Diffusion: passive movement of particles from a region of high concentration to a region of low concentration.
Osmosis: passive movement of water molecules from a region of lower solute concentration to a region of higher concentration.
Isite.lps.org
Simple & Facilitated Diffusion
Simple Diffusion –there is no expenditure of energy in moving the molecules across the membrane.
Facilitated Diffusion – larger molecules move passively through the membrane via channel proteins.
sjcabiology.wikispaces.com
Active Transport
Molecules moving from low to high concentration must be actively moved.
Kenp
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net
Video
Cytosis:A transport mechanism for the movement of
large quantities.Exocytosis: vesicle membrane fuses with the
plasma membrane.Endocytosis: a vesicle is formed by the in
folding of the plasma membrane.
Material Transport
o Phospholipid molecules can change places in the horizontal plane (creates fluidity).
o Molecule exchange in the vertical plane DOES NOT occur (maintains integrity).
Video
Inner Life of a Cell2007 – the President and Fellows of Harvard College
EXPLORATION PHASE
Tissue or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis. Complete the exploration phase for the lab with the following aim:
To determine the osmolarity of an unknown substance by bathing samples in hypotonic and
hypertonic solutions.
"Age-Related Diseases (Aging) Part 3." Whatwhenhow RSS. N.p., n.d. Web. 30 July 2014.Armstong, W. P. "Molecule Illustrations." Molecule Illustrations. N.p., May 2012. Web. 30 July 2014."A Vízről - Kristálytiszta Víz." A Vízről - Kristálytiszta Víz. N.p.,
n.d. Web. 30 July 2014.Floyd, Claire C. "Evolutionary Baggage." : Making Heads or Tails of Phospholipids. N.p., 26 Nov. 2012. Web. 30 July 2014.Pace, C. "C. Pace's Class - Honors Biology: The Cell Membrane
and Cellular Transport." C. Pace's Class - Honors Biology: The Cell Membrane and Cellular Transport. N.p., 5 Dec. 2013. Web. 30 July 2014.Percec, Virgil. "Chemical Year in Review 2010." Chemical and
Engineering News. N.p., n.d. Web. 30 July 2014.