Lesson 1 - Observing cells Flashcards
meaning light microscope
a tool that uses a beam of light and optical lenses to magnify specimens up to 1500 times life size
meaning electron miscroscope
a tool that uses a beam of electrons and magnetic lenses to magnify specimens up to 500 000 times life size
meaning magnification
a measure of how much bigger the image you see is than the real object
meaning resolution (resolving power)
a measure of how close together 2 objects can be before they are seen as 1
meaning Transmission Electron Micrographs (TEMs)
micrographs produced by the electron microscope that give 2D images like those from a light microscope, but magnified up to 500 000 times
meaning Scanning Electron Micrographs (SEMs)
micrographs produced by the electron microscope that have a lower magnification than TEMs, but produce a 3D image
what did Robert Hooke invent
the first working optical microscope
what did Anton van Leeuwenhoek discover
bacteria
what did Nehemiah Grew invent
the first accurate drawing of tissues
what did Matthias Schleiden and Theodor Schwann discover
cells are the basic units of life
how to calculate total magnification
magnification of objective lens * magnification of eyepiece lens
haematoxylin
stains the nuclei of plant and animal cells purple, blue or brown
methylene blue
stains the nuclei of animal cells blue
acetocarmine
stains the chromosomes in dividing nuclei in animal and plant cells
iodine
stains starch-containing material in plant cells blue-black
state 3 advantages of the light microscope
-can see living plant and animal cells directly
-cheap and available
-light and portable
state 1 disadvantage of the light microscope
-limited powers of resolution and magnification
state 1 advantage of the electron microsope
-high powers of resolution and magnification
state 3 disadvantages of the electron microscope
-can only examine dead specimen as vacuum used
-expensive
-large and not portable
