topic one - cell structure - miss whitehouse Flashcards
state three things to do when drawing microscopes?
label lines
draw in pencil
informative title
define ‘magnification’
how much an image has been enlarged by compared to it’s original object
define ‘resolution’
the degree to which you can distinguish two close objects as being separate
formula for magnification?
image/actual
what’s light microscope?
used to look at whole cells or tissues, focus a beam of lights onto the specimen
ads - cheap and easy to use
LSCM?
how to get from nm (nanometres) to um(micrometres)?
divide by 1000
how to get from um(micrometres) to mm?
how to get from nm (nanometres) to um(micrometres)?
divide by 1000
divide by 1000
what is the average animal cell size?
10-50um (micrometres)
what is the average plant cell size?
10-100um (micrometres)
what is the average bacterial cell size?
1um (micrometres)
what are the two different types of microscopes?
transmission electron microscope (TEM)
scanning electron microscope (SEM)
define ‘TEM microscopes’ and explain how it works?
an electron microscope uses a focused beam
of electrons is used instead of light to
“see through” the specimen
the electrons pass through a very thinly
cut specimen and produce 2D images
define ‘SEM microscopes’ and what it does?
the beam of electrons is directed onto the specimen through a vacuum, the electrons bounce off the surface of the specimen and are sensed by a detector. these microscope produce 3D images
define ‘LSCM’ and explain how it works?
laser scanning confocal microscope
an laser beam is focused onto the specimen the specimen being scanned is tagged with fluorescent dye
when the laser hits the dyes they emit fluorescent light, which is sensed by a detector and produces a clear image
draw and label a light microscope?
diagram/check with the one in biology workbook
what is the magnification and resolution of ‘TEM’
what is the magnification and resolution of ‘LM’
magnification - up to *500,000
resolution - between 0.05-1nm
magnification - 1500
resolution - 200nm
define ‘a light microscope’
use lenses to focus rays of light to
produce a clear image. specimens must be sliced thinly so light can pass through them
what is the magnification and resolution of ‘TEM’?
magnification - up to *500,000
resolution - between 0.05-1nm
what is the magnification and resolution of ‘SEM’?
magnification - up to *100,000
resolution - 5-50nm
which microscope had the higher magnification, ‘TEM’ or ‘SEM’?
transmission electron microscope
which microscope ‘TEM’ or ‘SEM’ has the strongest resolution?
transmission electron microscope
Q: a nucleus measures 100mm, with a magnification of x1000 and what is the actual size a nucleus?
A: 100000/10000= 10um
practice some magnification questions using the OLC?
magnification
define ‘graticules’
graticules are measuring devices used in microscopy
what are the two types of graticules called?
eyepiece graticules
stage micrometres
what is an eyepiece graticules and how does they work?
a smaller ruler etched onto the microscope ‘s eyepiece,
there are no units and it represents different lengths at different magnifications
when you increase the magnification the image becomes larger but the actual size of the specimen hasn’t changed - the eyepiece scale must be marked for each objective lenses
what is an stage micrometre and how does it work?
a special microscope slide etched with a ruler exactly 1mm long, with 100 divisions
it is used to calibrate the eyepiece