Cell Membrane Structure and Function

Study Notes

Cell Membrane

Also known as the plasma membrane
Outermost layer of the cell
Semi-permeable, allowing certain substances to pass through while keeping others out
Composed of:
- Phospholipid bilayer (main component)
- Proteins (integral and peripheral)
- Cholesterol (stabilizes the membrane)
- Carbohydrates (attached to proteins or lipids)
Functions:
- Regulates what enters and leaves the cell
- Maintains cell shape
- Provides mechanical support
- Involved in cell signaling and communication

Mitochondria

Often referred to as the "powerhouses" of the cell
Found in eukaryotic cells
Responsible for generating most of the cell's energy (ATP) through cellular respiration
Composed of:
- Outer membrane
- Inner membrane (highly folded, increases surface area)
- Intermembrane space
- Mitochondrial matrix (site of citric acid cycle and fatty acid oxidation)
Functions:
- Generates ATP through cellular respiration (aerobic and anaerobic)
- Regulates cell growth and division
- Involved in apoptosis (programmed cell death)
- Maintains cellular calcium levels

Plasma Membrane (additional details)

Fluid mosaic model: describes the arrangement of proteins and lipids in the membrane
Selective permeability: allows certain substances to pass through while keeping others out
Passive transport: movement of molecules from high to low concentration without energy input (diffusion, osmosis, facilitated diffusion)
Active transport: movement of molecules from low to high concentration using energy input (carrier proteins, pumps)
Cell-cell recognition and communication: plasma membrane proteins and carbohydrates involved in cell adhesion and signaling

Cell Membrane

The outermost layer of the cell, also known as the plasma membrane
Semi-permeable, allowing certain substances to pass through while keeping others out
Composed of a phospholipid bilayer, proteins, cholesterol, and carbohydrates
Phospholipid bilayer is the main component, with hydrophilic heads and hydrophobic tails
Proteins are integral (span the membrane) or peripheral (attached to the surface)
Cholesterol stabilizes the membrane, while carbohydrates are attached to proteins or lipids
Regulates what enters and leaves the cell, maintaining cell shape and providing mechanical support
Involved in cell signaling and communication

Mitochondria

Found in eukaryotic cells, responsible for generating most of the cell's energy (ATP)
Composed of outer and inner membranes, intermembrane space, and mitochondrial matrix
Inner membrane is highly folded, increasing surface area for energy production
Mitochondrial matrix is the site of citric acid cycle and fatty acid oxidation
Generates ATP through cellular respiration (aerobic and anaerobic)
Regulates cell growth and division, involved in apoptosis (programmed cell death)
Maintains cellular calcium levels

Plasma Membrane Function

Fluid mosaic model describes the arrangement of proteins and lipids in the membrane
Selective permeability allows certain substances to pass through while keeping others out
Passive transport: diffusion, osmosis, and facilitated diffusion (no energy input)
Active transport: movement of molecules from low to high concentration using energy input
Cell-cell recognition and communication involve plasma membrane proteins and carbohydrates
Cell adhesion and signaling are also mediated by plasma membrane proteins and carbohydrates

Description

Learn about the cell membrane, its composition, and functions in regulating cellular activities. Explore the phospholipid bilayer, proteins, cholesterol, and carbohydrates that make up this crucial layer.