Biology

• Cell theory


  • All living things are composed of cells
  • Cells are the basic units of structure and function in living things
  • New cells are produced from existing cells
• Image


  The microscope view
• Magnification


  How many times larger the image is than the object
• Resolution


  The shortest distance two objects can be a part due to the camera quality
• Measurements


  • 1m=100cm=1000mm
  • 1cm=0.01m (10 to the power of -2m)
  • 1mm=0.001m (10 to the power of -3m)
  • 1um=10 to the power of -6m
  • 1nm=10 to the power of -9m
• Light microscopes


  Easy, cheap, rely on light, and their resolution is limited to 0.2 micrometres
• Electron microscopes


  Use electrons instead of light, max resolution is 0.1 micrometres (2000 times better than light microscopes)
• Cryogenic electron microscopy


  Allows scientists to view proteins and other biomolecules which do not readily crystalise
• Freeze fracture electron microscopy


  Allows scientists to view a specimen by freezing it and then fracturing it to examine the insides
• Fluorescent stains/ immunofluorescence in light microscopy


  Used to visualize a specific protein or antigen in cells or tissues by binding a specific antibody chemically attached to a fluorescent dye
• Advantages of fluorescent stains

  • It allows scientists to study the location, distribution, and quantity of biomolecules as it is so specific
  • Fluorescent stains can be used with living tissue
  • The stain can detect molecules at low concentrations
• Structures common to all cells

  • Phospholipid plasma membrane
  • Cytoplasm
  • DNA
• Prokaryotic cell


  The prokaryotic cells are mostly bacteria and archaea, mostly small and unicellular
• Features of a prokaryotic cell

  • Cell wall
  • Plasma membrane
  • Cytoplasm
  • 70S ribosomes
  • Nucleoid region
  • Flagellum
  • Pillus
  • Binary fission
• Cell wall


  Provides the cell with strength and support, it also prevents the cell from bursting
• Plasma membrane


  Controls what enters and exits the cell (composed of phospholipids)
• Cytoplasm


  Where most of the metabolism occurs, mostly consists of water
• 70S ribosomes


  Responsible for protein synthesis
• Nucleoid region


  Contains a single circular chromosome. It contains DNA which contains information on the growth and development of the cell
• Flagellum


  Responsible for locomotion
• Pillus


  Allows the bacteria to adhere to each other and other surfaces, it also allows the exchange of genetic material between bacteria
• Binary fission


  The process of prokaryotic cells dividing results in two daughter chromosomes
• Plasma membrane


  Controls what enters and exits the cell. The plasma membrane is composed of phospholipids
• Cytoplasm


  Most of the metabolism that occurs in the cell occurs in the cytoplasm. The cytoplasm is mostly composed of water
• 80S ribosomes


  Responsible for protein synthesis
• Nucleus


  Chromosomes associated with histone proteins are located in the nucleus. The nucleus has a double membrane with pores that allow mRNA to enter the cytoplasm
• Chromosomes


  Composed of DNA wrapped around histone proteins. DNA is the genetic material with information for the growth and development of the cell
• Mitochondrion


  Aerobic respiration, producing ATP
• Vacuoles


  Plants have large vacuoles (central vacuoles) involved in storing nutrients. Small vacuoles are found in animal cells and are involved in the removal of waste
• Lysosome


  Specialised vesicles, that contain enzymes. They are involved in the digestion of old/damaged molecules to break them down
• Phagocytosis


  The process by which solid materials, such as bacteria, are taken into a cell by endocytosis. A bacterium is taken into a cell by endocytosis, forming a phagocytic vacuole. Lysosomes fuse with the phagocytic vacuole to form a phagosome. The lysosome's enzymes digest the bacterium
• Rough endoplasmic reticulum


  A membrane structure with ribosomes attached. It's involved in transporting proteins to the Golgi apparatus. Production of membrane phospholipids and cellular lipids. Production of testosterone and oestradiol. Detoxifies drugs in the liver. Stores calcium ions in the muscle cells
• Smooth endoplasmic reticulum


  Involved in lipid synthesis, and detoxification
• Golgi apparatus


  Modifies and packages proteins to be exported from the cell
• Cytoskeleton


  Composed of protein microtubules, and is involved in maintaining cell shape, moving organelles, and nuclear division
• Chloroplast


  Occurs in algae and plant cells and produces energy through photosynthesis. Grana is a pile of thylakoids. Thylakoids are flattened membrane sacs that allow it to absorb light (needed for photosynthesis). Strom is like the cytoplasm of the chloroplast and contains enzymes and chemicals that allow the completion of photosynthesis
• Centrosome


  Organises microtubules that provide structure and allow movement
• Similarities between prokaryote and eukaryote cells

  • Both have DNA
  • Both conduct all the functions of life
  • Both have an outside boundary that involves the plasma membrane
• Differences between prokaryote and eukaryote cells

  • Organelles (membrane bound)
  • DNA
  • Plasmids
  • Size
  • Ribosomes
  • Cell wall
  • Cell membrane
  • Cytoplasm
• Unicellular organism


  Organisms that are made up of only one cell