Cell Membrane Structure and Functions

Questions and Answers

What is the primary function of the cell membrane's semipermeability?

Regulating the movement of molecules in and out of the cell

What is the term for the movement of molecules down their concentration gradient without using energy?

Passive transport

The cell membrane is completely impermeable to all molecules.

False

The ______________ model describes the phospholipid bilayer as dynamic and fluid, allowing molecules to move within the membrane.

fluid mosaic Signup and view all the answers

What is the term for the changes in membrane shape and structure that can influence cell behavior and function?

Membrane curvature Signup and view all the answers

Lipid rafts are regions of the membrane with uniform lipid and protein compositions.

False Signup and view all the answers

What are the two types of proteins embedded in the cell membrane?

Integral and Peripheral proteins Signup and view all the answers

Match the following cell membrane functions with their descriptions:

Semipermeability = Regulates the movement of molecules in and out of the cell Cell signaling = Involved in cell-to-cell communication and signaling pathways Protection = Provides a barrier against external environment and maintains internal cellular environment Cell recognition = Helps cells recognize and respond to their environment Signup and view all the answers

Study Notes

Cell Membrane

Structure

Phospholipid bilayer: composed of two layers of phospholipid molecules with their hydrophilic (water-loving) heads facing outwards and hydrophobic (water-fearing) tails facing inwards
Embedded proteins: integral proteins (span the membrane) and peripheral proteins (attached to the surface)

Functions

Semipermeability: regulates the movement of molecules in and out of the cell
Protection: provides a barrier against external environment and maintains internal cellular environment
Cell signaling: involved in cell-to-cell communication and signaling pathways
Cell recognition: helps cells recognize and respond to their environment

Permeability

Selective permeability: allows certain molecules to pass through while restricting others
Passive transport: movement of molecules down their concentration gradient (e.g. diffusion, osmosis)
Active transport: movement of molecules against their concentration gradient using energy (e.g. pumps, transport proteins)

Fluidity and Flexibility

Fluid mosaic model: the phospholipid bilayer is dynamic and fluid, allowing molecules to move within the membrane
Lipid rafts: specialized regions of the membrane with distinct lipid and protein compositions
Membrane curvature: changes in membrane shape and structure can influence cell behavior and function

Cell Membrane

Structure

Phospholipid bilayer is composed of two layers of phospholipid molecules with hydrophilic heads facing outwards and hydrophobic tails facing inwards
Integral proteins span the membrane, while peripheral proteins are attached to the surface

Functions

Semipermeability allows the cell membrane to regulate molecular movement in and out of the cell
Provides protection by maintaining internal cellular environment and acts as a barrier against external environment
Involved in cell-to-cell communication and signaling pathways through cell signaling
Enables cell recognition and response to environment

Permeability

Selective permeability allows certain molecules to pass through while restricting others
Passive transport occurs through diffusion and osmosis, moving molecules down their concentration gradient
Active transport moves molecules against their concentration gradient using energy, involving pumps and transport proteins

Fluidity and Flexibility

Fluid mosaic model depicts the phospholipid bilayer as dynamic and fluid, allowing molecule movement within the membrane
Lipid rafts are specialized regions with distinct lipid and protein compositions
Changes in membrane curvature influence cell behavior and function