Biology 8 (Cells)

• Cell Theory


  • All living things are made up of cells
  • Cells are the smallest working units of all living things
  • All cells come from preexisting cells through cell division
• Cell


  The smallest unit that is capable of performing life functions
• Examples of Cells

  • Amoeba Proteus
  • Plant Stem
  • Red Blood Cell
  • Nerve Cell
  • Bacteria
• Prokaryotic Cells


  • Do not have structures surrounded by membranes
  • Few internal structures
  • One-celled organisms, Bacteria
• Eukaryotic Cells


  • Contain organelles surrounded by membranes
  • Most living organisms
• Eukaryotic Cells


  • Plant
  • Animal
• Cell Membrane


  • Outer membrane of cell that controls movement in and out of the cell
  • Double layer
• Cell Wall


  • Most commonly found in plant cells & bacteria
  • Supports & protects cells
• Nucleus


  • Directs cell activities
  • Separated from cytoplasm by nuclear membrane
  • Contains genetic material - DNA
• Nuclear Membrane


  • Surrounds nucleus
  • Made of two layers
  • Openings allow material to enter and leave nucleus
• Chromosomes


  • In nucleus
  • Made of DNA
  • Contain instructions for traits & characteristics
• Nucleolus


  • Inside nucleus
  • Contains RNA to build proteins
• Cytoplasm


  • Gel-like mixture
  • Surrounded by cell membrane
  • Contains hereditary material
• Endoplasmic Reticulum


  • Moves materials around in cell
  • Smooth type: lacks ribosomes
  • Rough type: ribosomes embedded in surface
• Ribosomes


  • Each cell contains thousands
  • Make proteins
  • Found on ribosomes & floating throughout the cell
• Mitochondria


  • Produces energy through chemical reactions – breaking down fats & carbohydrates
  • Controls level of water and other materials in cell
  • Recycles and decomposes proteins, fats, and carbohydrates
• Golgi Bodies


  • Protein 'packaging plant'
  • Move materials within the cell
  • Move materials out of the cell
• Lysosome


  • Digestive 'plant' for proteins, fats, and carbohydrates
  • Transports undigested material to cell membrane for removal
  • Cell breaks down if lysosome explodes
• Vacuoles


  • Membrane-bound sacs for storage, digestion, and waste removal
  • Contains water solution
  • Help plants maintain shape
• Chloroplast


  • Usually found in plant cells
  • Contains green chlorophyll
  • Where photosynthesis takes place