CHAPTER 7:
MEMBRANE STRUCTURE AND FUNCTION
SELECTIVE PERMEABILITY AND ITS ROLE
● This refers to the membrane that allows some substances or molecules to enter the cell while also
preventing substances or molecules from entering
○ Mainly based on the size and concentration of the molecules
○ Important in maintaining homeostasis, and cellular health, and balancing electrolytes
AMPHIPATHIC MOLECULES
● The phospholipids are both hydrophilic (water lovers) and hydrophobic (fear of water)
FLUID MOSAIC MODEL OF MEMBRANE STRUCTURE
● A fluid structure where various proteins are embedded in or attached to the bilayer of phospholipids.
○ explains how membranes can regulate the cell's molecular traffic
● Mosaic: proteins that are made up of many different components
○ Consisting of fluids or elastic double layer
○ made up of lipid molecules and large protein molecules
MEMBRANE FLUIDITY & INFLUENCES
● When the temperature is decreasing/lowering
○ Can switch from a fluid state to a solid state when the phospholipids are more closely packed.
● Factors
○ Temperature
○ length of the fatty acid tail
○ cholesterol content
ROLE OF STEROIDS IN ANIMAL CELL MEMBRANES
● Acts as a precursor within animals cells
○ The precursor molecule helps with the synthesis of other important steroid, such as hormones
MAJOR MAIN FUNCTIONS OF MEMBRANE PROTEINS
● Transport
○ An exchange of molecules with their kinetic energy and momentum to help move across the
boundaries between the adjacent layer of fluids to the membrane itself
○ Movement of chemicals inside or around the cell
○ A transport protein is specific for the substance it translocates for certain substances cross the
membrane
● Enzyme Activity
○ Protein that is built onto the membrane with an exposed active site
● Signal Transportation
○ The linkage of mechanical, chemical, and electromagnetic stimulus for a specific response from
the cell
MEMBRANE STRUCTURE AND FUNCTION
SELECTIVE PERMEABILITY AND ITS ROLE
● This refers to the membrane that allows some substances or molecules to enter the cell while also
preventing substances or molecules from entering
○ Mainly based on the size and concentration of the molecules
○ Important in maintaining homeostasis, and cellular health, and balancing electrolytes
AMPHIPATHIC MOLECULES
● The phospholipids are both hydrophilic (water lovers) and hydrophobic (fear of water)
FLUID MOSAIC MODEL OF MEMBRANE STRUCTURE
● A fluid structure where various proteins are embedded in or attached to the bilayer of phospholipids.
○ explains how membranes can regulate the cell's molecular traffic
● Mosaic: proteins that are made up of many different components
○ Consisting of fluids or elastic double layer
○ made up of lipid molecules and large protein molecules
MEMBRANE FLUIDITY & INFLUENCES
● When the temperature is decreasing/lowering
○ Can switch from a fluid state to a solid state when the phospholipids are more closely packed.
● Factors
○ Temperature
○ length of the fatty acid tail
○ cholesterol content
ROLE OF STEROIDS IN ANIMAL CELL MEMBRANES
● Acts as a precursor within animals cells
○ The precursor molecule helps with the synthesis of other important steroid, such as hormones
MAJOR MAIN FUNCTIONS OF MEMBRANE PROTEINS
● Transport
○ An exchange of molecules with their kinetic energy and momentum to help move across the
boundaries between the adjacent layer of fluids to the membrane itself
○ Movement of chemicals inside or around the cell
○ A transport protein is specific for the substance it translocates for certain substances cross the
membrane
● Enzyme Activity
○ Protein that is built onto the membrane with an exposed active site
● Signal Transportation
○ The linkage of mechanical, chemical, and electromagnetic stimulus for a specific response from
the cell
