Cell Biology

• Eukaryotic cells


  Cells that contain their genetic material enclosed in a nucleus
• Eukaryotic cells


  • Contain a nucleus
  • Contain a cell membrane
  • Contain cytoplasm
• Prokaryotic cells


  Cells where the genetic material is not enclosed in a nucleus
• Prokaryotic cells


  • Do not have a nucleus
  • Have a cell membrane
  • Have a cell wall
  • Contain cytoplasm
  • May have plasmids
• Prokaryotic cells


  Are much smaller than eukaryotic cells
• Meter


  The base unit of measurement in science
• Sizes in biology

  • Often much smaller than a meter
• Centi


  One hundredth
• Centimeter (cm)


  One hundredth of a meter
• Size of objects

  • Width of little finger is around 1 cm
• Milli


  One thousandth
• Millimeter (mm)


  One thousandth of a meter
• Micro


  One millionth
• Micrometer (μm)


  One millionth of a meter
• Size of objects

  • Typical human cell is 10-20 micrometers in size
• Nano


  One billionth
• Nanometer (nm)


  One billionth of a meter
• Size of objects

  • Hemoglobin molecule is around 5 nanometers in diameter
• Prefixes centi, milli, micro, and nano are used to describe sizes in science
• Smaller units like micrometers and nanometers are used to measure the size of cells and their components
• Order of magnitude


  A way to compare the approximate size of different objects
• Order of magnitude

  Every order of magnitude is ten times greater than the one before
• The number of zeros tells you the order of magnitude
• Calculating order of magnitude

  1. Count the number of zeros

  2. Each zero represents one order of magnitude
• Eukaryotes


  Organisms whose genetic material is enclosed in a nucleus
• Nucleus


  Encloses the genetic material
• Cytoplasm


  Watery solution where chemical reactions take place, including the first stage of respiration
• Cell membrane


  Controls the molecules that can enter and leave the cell
• Mitochondria


  Where aerobic respiration takes place
• Ribosomes


  Sites of protein synthesis
• Mitochondria and ribosomes are too small to be seen using a light microscope, so an electron microscope is needed
• Proteins carry out many functions, such as enzymes
• Plant cell


  Differs from animal cells in regular shape, packed with green structures (chloroplasts)
• Plant cell


  • Contains nucleus, cytoplasm, cell membrane, mitochondria, ribosomes
  • Contains chloroplasts, cell wall, large permanent vacuole
• Chloroplasts


  Green structures that contain chlorophyll and are sites of photosynthesis
• Cell wall


  Made from cellulose, strengthens the cell
• Vacuole


  Large permanent structure filled with cell sap, helps give the plant cell its shape
• Plant cells are eukaryotes, like animal cells
• Nucleus contains genetic material
• Cytoplasm is where chemical reactions take place