Chapter 5 Learning Outcomes

Distinguish between a channel protein and a carrier protein

Channels: Tunnels through membrane Carriers: Actually bind transport cargo and move it across the membrane

Describe how proteins and lipids move within the membrane

proteins and lipids can move side to side in the membrane, but cant move vertically

Identify and describe the modification that is common for proteins and lipids in the outer layer of the bilayer. Describe how this relates to ABO blood type

Glycosylation = Attachment of a carbohydrate to something else Glycoproteins = Glycosylated protein Glycolipids = Glycosylated lipid Glycosylation is a very common modification for proteins and lipids that will be in the outer membrane of the plasma membrane These carbohydrates also can serve as "cell surface markers" different sugar markers mark different blood types

Explain how the fluidity of a membrane changes with its lipid composition

More saturated = More rigid • More unsaturated = More fluide • Temperature also affects fluidity • Colder = less fluid • Warmer = more fluid • Organisms can alter their membrane lipid composition • Lipid composition also varies between different organism

Explains the concept of osmosis, and predict the net direction of movement of water between two solutions separated by a selectively permeable membrane

Osmosis = Diffusion of water Water diffusion is based on solute concentrations (what is dissolved in water) Water diffuses from lower solute concentration to higher solute concentration)

Explain the concept of sidedness in a plasma membrane

Outer layer composition and inner layer composition will differ in the same membrane Asymmetrical distribution of membrane components Plasma membrane is derived from vesicles originating at the ER/Golgi What is inside the ER and Golgi apparatus ends up outside the cell

Describe the role of cholesterol in the membrane

Rigid ring structure Length = one layer of bilayer Warm temperatures: Rigid cholesterol prevents membrane from becoming too fluid Cool temperatures: Ring structure prevents phospholipid tails from tight packing Cholesterol is a "fluidity buffer" in the membrane

Explain the concept of the fluid mosaic model as it relates to the plasma membrane

The fluid mosaic model explains various observations regarding the structure of functional cell membranes. The model, which was devised by SJ Singer and GL Nicolson in 1972, describes the cell membrane as a two-dimensional liquid in which that restrict the lateral diffusion of membrane components

Describe the basic structure and composition of the plasma membrane

The plasma membrane is made up of a phospholipid bilayer which has polar head and hydrophobic tails that face each other keeping water out. There are proteins embedded in the membrane to selectively facilitate the movement of particles across the membrane.

Identify and explain the role of the plasma membrane in the cell

The primary function of the plasma membrane is to protect the cell from its surroundings. Composed of a phospholipid bilayer with embedded proteins, the plasma membrane is selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells.

Identify and describe the six basic functions of membrane proteins

Transport. Enzymatic activity. Signal transduction. Cell-cell recognition. Intercellular joining. Attachment to the cytoskeleton and extracellular matrix (ECM)

Explain what selective permeability means with the respect to a cell membrane (what can pass through the lipid bilayer and what can not)

What can pass directly through lipid bilayer: Anything non-polar (hydrophobic) Very small polar molecules What cannot: Larger polar molecules Anything ionic (Na+, etc.) These will require proteins for transport = Transport Proteins

Predict the behavior of an animal cell when placed in a solution that is: a. Isotonic b. Hypotonic c. Hypertonic

When a cell is placed in a solution - that solution can be described as: Isotonic: [Solution] = [Cell] No net osmosis Hypertonic: [Solution] > [Cell] Net osmosis is out of cell Hypotonic: [Solution] < [Cell] Net osmosis is into cell

Compare and contrast diffusion and active transport with respect to: a. Mechanism of action b. Whether or not energy is required c. Relationship of direction of movement to concentration gradient

diffusion moves with concentration gradient, does not require energy to trasport. active transport goes against concentration gradient. requires energy

Identify what "side" of a vesicle derived from the ER or Golgi becomes the outside for the plasma membrane

the inside of the vesicle

Explain the relationship between amino acids composition and whether or not a protein can permeate the phospholipid bilayer

the specific structure and therfore polarity and hydrophilic/hydrophobic tendencies of amino acids determine where and if the can permeate the phospholipid bilayer