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
• Eukaryotic cells include animal and plant cells
• Prokaryotic cells include bacterial cells
• Prefixes like centi, milli, micro, and nano are used to describe very small sizes in biology
• Order of magnitude

  A way to compare the approximate size of different objects
• How to determine order of magnitude

  Count the number of zeros - each zero represents one order of magnitude (10 times greater)
• Calculating order of magnitude difference

  1. Divide the larger measurement by the smaller measurement to get the number of times larger

  2. Count the number of zeros to determine the order of magnitude
• 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
• Organisms can be Prokaryotes or Eukaryotes
• Prokaryotic cells


  • Safe and simple
  • Made up of single-edge
• Subcellular structures all cells have


  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Nucleus


  Contains genetic material that controls the activities of the cell
• Cytoplasm


  Gel-like substance where most of the chemical reactions take place
• Cell membrane


  Holds the cell together and controls what goes in and out
• Mitochondria


  Where most of the respiration takes place, which transfers energy the cell needs to work
• Additional structures plant cells have


  • Rigid cell wall
  • Permanent vacuole
  • Chloroplasts
• Rigid cell wall


  Made of cellulose, supports the cell and strengthens it
• Permanent vacuole


  Contains a weak solution of sugar and salts
• Chloroplasts


  Where photosynthesis occurs, which makes food for the plant. They contain chlorophyll which absorbs light needed for photosynthesis
• Bacterial cells are much smaller than plant and animal cells
• Bacterial cells


  • Don't have a 'true' nucleus, instead have a single circular strand of DNA that floats freely in the cytoplasm
  • May also contain one or more small rings of DNA called plasmids
  • Don't have chloroplasts or mitochondria
• Specialized animal cells


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

  When cells become specialized
• 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
• Root hair cells


  • Increase the surface area of the root to absorb water and dissolved minerals more effectively
  • Do not contain chloroplasts
• Xylem cells


  • Have very thick walls containing lignin to provide support
  • Have no internal structures like nucleus, cytoplasm, vacuole or chloroplasts to allow easy flow of water and dissolved minerals
• Phloem cells


  • Consist of two types: phloem vessel cells with no nucleus and limited cytoplasm, and companion cells with mitochondria to provide energy to the phloem vessel cells
  • Phloem vessel cells have porous end walls called sieve plates to allow flow of dissolved sugars
• Xylem cells form long tubes that carry water and dissolved minerals from the roots to the leaves
• Phloem tubes carry dissolved sugars up and down the plant
• Optical microscope


  Used to look at cells on a prepared microscope slide
• Optical microscope


  • Has a stage to place the microscope slide
  • Has a light source (lamp or mirror) to illuminate the slide
  • Has objective lenses with different magnifications (4x, 10x, 40x)
  • Has an eyepiece lens with 10x magnification
  • Has coarse and fine focusing dials