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.

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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.