B1

• 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
• Eukaryotic cells include animal and plant cells
• Prokaryotic cells include bacterial cells
• Order of magnitude


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


  • Shows how many times larger one object is compared to another
  • Every order of magnitude is 10 times greater than the one before
• Objects of different orders of magnitude

  • Pineapple and lemon (1 order of magnitude)
  • Dog and woodlouse (2 orders of magnitude)
• Determining order of magnitude

  1. Count the number of zeros

  2. Each zero represents 1 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
• Cell membrane


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


  Where aerobic respiration takes place
• Ribosomes

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


  Unlike animal cells, plant cells have a regular shape and are packed full of green structures
• Plant cell


  • Has a nucleus containing genetic material
  • Has a cytoplasm where chemical reactions take place
  • Has a cell membrane controlling what enters and leaves the cell
  • Has mitochondria carrying out aerobic respiration
  • Has ribosomes as the site of protein synthesis
• Plant cell


  • Has chloroplasts containing chlorophyll and sites of photosynthesis
  • Has a cell wall made of cellulose to provide strength
  • Has a large permanent vacuole filled with cell sap to help maintain cell shape
• Plant cells are eukaryotes
• Algae are very simple forms of plant life and also have a cellulose cell wall
• Specialized animal cells


  Cells that have adaptations which help them carry out a particular function
• Differentiation


  When cells become specialized
• Sperm cells

  • Long tail to swim to ovum
  • Packed with mitochondria to provide energy for swimming
  • Contain enzymes to digest outer layer of ovum
• Fertilization


  The process where the genetic information of the ovum and sperm combine
• Nerve cells


  • Long axon to transmit electrical impulses
  • Axon covered in myelin to insulate and speed up transmission
  • Dendrites to increase surface area for connections
• Muscle cells


  • Contain protein fibers that can contract to shorten the cell
  • Packed with mitochondria to provide energy for contraction
• Muscle cells work together to form muscle tissue
• Microscope


  Used in biology to look at small things like cells and organelles
• Types of microscopes


  • Light microscope
  • Electron microscope
• Light microscope


  • Cheaper
  • Can see live things
  • Lower resolution
• Electron microscope


  • Higher resolution
  • Can only see dead things
• Prefixes for small measurements

  • Nanometer (10^-9 meters)
  • Micrometer (10^-6 meters)
  • Millimeter (10^-3 meters)
• Calculating real size of object


  Size of image / Magnification
• Calculating magnification


  Size of image / Real size of object
• Calculating size of image

  Magnification x Real size of object
• Cell types


  • Animal cells
  • Plant cells