Module 2, chapter 2, Basic components of living systems Flashcards
microscopy magnification and calibration more microscopy eukaryotic cell structure the ultrastructure of plant cells prokaryotic and eukaryotic cells
What is the function of the eyepiece lens
this is the lense closest to your eye it usually has a magnification of x10
What is the function of the objective lenses
these are three lenses of different strengths which can be used to magnify the images more clearly
what is the function of the stage
this is the place where you put a microscope slide, clips hold the slide in place
What is the function of the diaphragm
this controls the amount of light that goes onto the microscope slide
what is the function of the light
the light source projects light onto the the microscope slide, it can be a mirror or an electric bulb
what is the function of the base
this is very heavy to keep the microscope from falling over
what is the function of the arm
this holds the eyepiece lense above the stage
what is the function of the fine focus knob
this is used to focus the image, so it is very sharp and clear
what is the function of the coarse focus knob
this is used to focus the image so that you can see it clearly
uses, advantages and disadvantages of light microscopes
- uses light rays to observe an object
- natural colour of the specimen (or stains can be seen)
- (+) can observe living or dead things
- (+) does not use harsh chemicals
- (+) easy to set up and use
- (+) cheap and portable
- (-) low magnification - up to x2000
- (-) low resolution - resolving power 200nm
TEM uses advantages and disadvantages
Transmission Electron Microscope
- uses focused beams of electrons through sections of tissues
- black and white images
- (+) high magnification (above 5 million times)
- (+) high resolution (0.5 nm)
- (+) can see details inside cells
- (-) can only see dead material
- (-) harsh chemicals used in preparation, which can cause artefacts
SEM uses advantages and disadvantages
Scanning Electron Microscope
- uses focused beams of electrons reflected off the tissues
- black and white images
- (+) high magnification (above 5 million times)
- (+) high resolution (between 3 - 10 nm)
- (+) can see details on the surface of cells
- (-) expensive
- (-) needs a vacuum, so only dead material can be studied
LSCM uses advantages and disadvantages
Laser Scanning Confocal Microscope
- uses a laser beam of light to illuminate chemical stains withing the specimen, these then fluoresce
- (+) can see living cells
- (+) can observe cell processes by tracking fluorescent molecules
- (+) higher resolution than light microscopes
- (-) expensive
(-) complex to set up and use
what is magnification
the degree to which the size of the image is larger than the object itself
what is resolution
the degree to which it is possible to distinguish between two objects that are very close together
what is contrast
the difference in colour/shade between two objects
