Biology

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Cells, Exchange and Transport 

keywords and definitions 

  • Ultra Structure: The detailed structure of a cell/ as seen with an electron microscope
  • Organelle: Part of a cell with a distinct structure and function 

The two types of cells

Prokaryotic 

1-5 micrometers 

Lack membrane band organelles - no nucleus 

  • Capsule - Found in some bacterial cells, this additional outer covering protects the cell when it is engulfed by other organisms, assists in retaining moisture, and helps the cell adhere to surfaces and nutrients.

  • Cell Wall - Outer covering of most cells that protects the bacterial cell and gives it shape.

  • Cytoplasm - A gel-like substance composed mainly of water that also contains enzymes, salts, cell components, and various organic molecules.

  • Cell Membrane or Plasma Membrane - Surrounds the cell's cytoplasm and regulates the flow of substances in and out of the cell.

  • Pili - Hair-like structures on the surface of the cell that attach to other bacterial cells. Shorter pili called fimbriae help bacteria attach to surfaces.

  • Flagella - Long, whip-like protrusion that aids in cellular locomotion.

  • Ribosomes - Cell structures responsible for protein production.

  • Plasmids - Gene carrying, circular DNA structures that are not involved in reproduction.

  • Nucleiod Region - Area of the cytoplasm that contains the single bacterial DNA molecule.

Eukaryotic 

 Larger of the two cells (20-100 micrometers)

 Have non membrane bands - By compartmentising functions effeciency can be increased

  •  Nucleus: The nucleus is typically the largest

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