Question: Plasma membrane

Answer: Regulates passage of materials into and out of the cell, and helps maintain a life supporting interval environment. Acts as a barrier.

Question: List the components of a biological membrane:

Answer: 1)phospholipids(major component of membrane)

2)proteins(also major component)

3)sterols (cholesterol): inserted periodically to add stability

4)carbohydrates(cell-cell recognition & molecule binding)

(In order greatest to least)

*A membrane may block a particular substance at one time and actively promote its passage at another time.

Question: What is proteins role in the biological membrane?

Answer: 1)Transports stuff across membrane

2)anchors cells

3)catalyzes reactions

4)serves as receptors for chemical and electrical signaling

5)acts as “identification tags”

Question: What do biological membranes are _.

Answer: -semi-permeable - lets some stuff through (based off size and charge)

Question: Biological membranes let through…

Answer: 1)small, nonpolar(hydrophobic), compounds (ex. O2, CO2)

2)H2O, polar, but small (fits through cracks of lipid bilayer)

3)large, uncharged, polar(hydrophilic) molecules-enters/exits through transport proteins (ex. glucose) (hard to pass through)

4)ions-enters/exits through transport proteins (ex. Na+, K+, Cl-) (hard to pass through)

Question: Phospholipids

Answer: -amphiphatic: contains hydrophobic and hydrophilic region

-hydrophobic(nonpolar) fatty acid chains=”tail” (2 FA chains)

-hydrophilic charged phosphate group + polar organic compound=”head” (glycerol + PO4 + organic molecule)

(2 FA chains) + (glycerol + PO4 + organic molecule)

Question: Why do phospholipids form bilayers? (In water)

Answer: Because their molecules have…

1)polar heads that form hydrogen bonds with each other and water

2)then their nonpolar tails are pushed together

3)cylindrical shapes form that allow them to associate with water most easily as a bilayer

Question: Biological membrane structure-fluid mosaic model:

Answer: Cell membrane is a fluid lipid bilayer with a constantly changing “mosaic pattern” of associated proteins. Molecules embedded in the membrane can move along the plave of the membrane, producing an ever-changing configuration. (Describes membrane structure)

Question: Types of proteins in biological membrane:

Answer: 1)integral proteins

a)transmembrane proteins

b)peripheral proteins

Question: Integral proteins

Answer: Amphipathic proteins that span a portion of the phospholipid bilayer. (span entire bilayer)