More microscopy - 2.3 (6) Flashcards
Module 2, Chapter 2, 2.3, Page 24
What can electron microscopes not be used to examine?
living cells
What was always believed in regards to the maximum resolution for light microscopes?
that they had a maximum resolution of 0.2 micrometres
What is 0.2 micrometres half of?
half of the wavelength of light
What does the maximum resolution of light microscopes limit?
the detail that can be seen in living cells
In 2014, which 3 people were awarded the Noble Prize in Chemistry?
Eric Betzig, Stefan W.Hell, and William E Moerner
What did the 3 scientists receive the Nobel Prize for?
achieiving resolutions greater than 0.2 micrometres using light microscopy
How many principles were involved?
two
What did the two principles involve?
both forms of super resolution fluorescent microscopy (SRFM)
What did the one of the principles involve?
one building up a very high resolution image by combining many very small images
What did the other principle involve?
superimposing many images with normal resolution to create one very high resolution image
What did Stefan Hell develop?
stimulated emission depletion (STED)
What does stimulated emission depletion (STED) involve?
the use of two lasers which are slightly offset / unbalanced
STED - What does the first laser scan and what does it cause?
the laser scans a specimen which then causes fluorescence
STED - What happens after the laser causes fluorescence?
the second laser which negates / rejects the fluorescence from all but a molecular sized area
STED - What happens when a picture is built up from STED?
it is built up with a resolution much greater than that produced normally in light microscopy
STED - What happens to the individual strands of DNA?
they become visible
STED - Eric Betzig and William E.Moerner independently developed the second principle which relies on the ability to…
control the fluorescence of individual molecules
STED - Specimens are scanned multiple times but each time…
different molecules are allowed to fluoresce
STED - What happens when the images are superimposed?
the resoution of the combined images is at the molecular level, much greater than 200nm
Is it possible to follow individual molecules during cellular processes?
yes
Proteins involved in Parkinson’s and Alzheimer’s diseases can be observed interacting and fertlised eggs dividing into…
embyos can be studied at a molecular level (at a close level)
