microscopes Flashcards
chapter 3
do humans have a higher resolution than binoculars?
no it does not
why do we use stains?
we use stain on bacteria cells before viewing it on bright field microscopy, because the cell cytoplasm of bacterial cells usually lacks colour and makes it difficult to see the cells called the field.
simple stain technique
is when a basic cationic dye is used on heat fixed smear. since the dye is a cationic and the cytoplasm is negative charged, they attract causing us to see cell size, their arrangements and shape
heat fixation
is a bacteria that has been through flames to bond the cells to microscopic slide
negative stain
is when cells that unable to stain are put on a dark background
- it avoids heat fixation
differential stain uses which 2 colour dye?
gram staining and acid-fast technique
gram stain technique
cells are differentiated by colour:
- gram positive was blur-purple
- gram negativ: orange- red
acid- fast technique
use to identify mycobacterium species from tuberculosis.
- difficult to stain because cell have waxy wall that repel dye used in gram stain
spore stain technique
use to differentiate cells from spores
phase- contrast
it s used to study organisms that are unstained
- splits the light beam and throws the light ray out of phase
dark field
helps to identify small pathogens near the limit of resolution with the light microscope
- it has condenser lens that scatter the light and causes it to hit the specimen from the side
flourescence
cells glow due to the presence of fluorescent antibody that binds to that cell
the scanning electron
focus on electron- beam over a surface to create an image
transmission electron microscope
uses magnets to focus on beam of electrons.
- it is a microscopic technique in which a beam of electrons is transmitted through a specimen to form an image, on a screen or a TV
which microscopes can view living samples?
light microscope
