Cell Structure and Function

Study Notes

Cell Structure and Function

Cell Membrane

A thin, semi-permeable membrane that surrounds the cell
Composed of phospholipid bilayer with embedded proteins
Regulates what enters and leaves the cell
Maintains cell shape and provides mechanical support

Cell Organelles

Specialized structures within the cell that perform specific functions
Examples:
- Nucleus: contains genetic material (DNA)
- Mitochondria: generates energy for the cell
- Endoplasmic Reticulum (ER): involved in protein synthesis and transport
- Ribosomes: site of protein synthesis
- Lysosomes: contain digestive enzymes for breaking down waste and foreign substances

Function of Plasma Membrane

Controls the movement of molecules in and out of the cell
Regulates the exchange of nutrients, waste, and signaling molecules
Maintains cell homeostasis and osmotic balance

Diffusion in Cells

The movement of molecules from an area of higher concentration to an area of lower concentration
Types of diffusion:
- Passive diffusion: movement down concentration gradient (e.g., diffusion of oxygen into the cell)
- Facilitated diffusion: movement down concentration gradient using transport proteins (e.g., glucose uptake)
- Active transport: movement against concentration gradient using energy (e.g., pumping ions out of the cell)

Composition of Living Organisms

Living organisms are composed of cells, which are the basic structural and functional units of life
Cells are made up of:
- Water (~70%)
- Organic compounds (carbohydrates, proteins, fats, nucleic acids)
- Inorganic compounds (salts, minerals)
- Organelles and other cellular structures

Description

Understand the components and functions of cell membranes, organelles, and other cellular structures, as well as the processes of diffusion and transport in cells. Learn about the composition of living organisms and how cells work together to maintain life.