Cell structure and microscopes Flashcards
how does a TEM work
stained by metal salts
beam of electrons passing through a specimen
darker the picture the more dense structure
What kind of images can you see from a TEM
2D black and white
organelles
how does an SEM work
beams of electrons are knocked off the cell surface
what image do you see from an SEM
3D images
black and white
surface
why do we stain cells
to distinguish between cells/organelles and recognise different cells/organelles
improving contrast
to see them more clearly
resolution and magnification of a light microscope
200x
200nm
magnification and resolution of a TEM
500,000
0.5nm
magnification and resolution of an SEM
100,00 x
10nm
how do you use an eyepiece graticule and stage micrometer to view a specimen
calibrate eye piece graticule by making the divisions align
Outline the functions of the cytoskeleton within a cell (3)
Cell support / stability / scaffold / maintain shape;
Movement of flagella / cilia / undulipodia;
Cytokinesis / change shape of cell / endo / exocytosis;
Holds organelles in place;
Moves vesicles;
Moves chromosomes / mRNA;
Forms spindle / centrioles
glucose + glucose =
maltose
what is the purpose of gram staining
To differentiate between gram positive and gram negative bacteria
What’s the stain and colour for gram positive bacteria
iodine/ crystal violet –> purple/blue
Whats the stain for gram negative bacteria
acetic orcein –> DNA red/pink
eosin –>cytoplasm /pink
Why do specimens have to be thin in microspcopy
to allow light to pass through
What are the advantages of light microscopes
Cheap
Portable
Easy to use - no training
living organisms
What are the disadvantages of light microscopes
low magnification and resolution
What type of staining is needed for electron microscopes
Metallic staining - lead
What can you see with a laser scanning confocal microscope
Depth of a cell
Evaluate the use of laser scanning confocal microscopes
Disadvantages - Lower mag an res then electron
Advantages - living cells , depth
Evaluate the use of electron microscopes
Disadvantages - Expensive ,training , non living organisms
Advantages - high mag and res
What’s the difference between the images seen in TEM and SEM
SEM can have added colour while TEM cant
TEM has a greater mag and res
What do samples have to be in an electron microscope before theyre viewed
dehydration
Whats the purpose of differential staining
Identify different cellular components and cell types
