General Cell Structure (DP IB Biology)

General Cell Structure

• All living organisms are comprised of cells

• These cells all have some common unifying features, including

  • DNA as genetic material

  • Cytoplasm 

  • A plasma membrane

DNA

• All living cells contain some sort of DNA, this varies between eukaryotic cells and prokaryotic cells

• The presence of DNA means that a new cell can be formed from an old cell, as genetic material is able to be stored and transferred

• DNA also controls the production of enzymes and other vital proteins within the cell

Cytoplasm

• Cytoplasm is found within the boundary of a cell

• It is composed of mainly water with dissolved substances, such as ions

• The fluid is known as cytosol

• Many of the cell's important reactions take place within the cytoplasm

Plasma membrane

• The plasma membrane surrounds the cell and encloses all the cell contents

• In all cell types, the plasma membrane has two layers and this is called a bilayer

• The bilayer consists of lipids; these vary depending on the type of organism 

• The membrane is responsible for controlling the interactions of the cell's interior with the exterior

  • Materials required by the cell are transported into the cell interior

  • Waste substances are exported out of the cell to the surrounding environment

• The membrane is studded with proteins which have varying functions including:

  • Cell recognition

  • Cell communication

  • Transport into and out of the cell