Sounds like some kind of moisturise aside from it wouldn't be zinc it would be zinc oxide. The sodium hydroxide is there to adjust the pH and I don't see why you'd need a safer substitute, the issue isn't the substance itself it's the concentration which is going to be pretty low.
Without the...
It doesn't, mRNa will come from only one copy of a gene. If you have two copies of a gene, one paternal and one maternal it is possible that both will be expressed and if one carries a mutation and one doesn't then both mutated and wild type protein may be present ( best example I can think of...
Size basically - a stand light microscope, even a really good one can't give you much more than basic shape - we're dealing with submicron particles, you can distinguish comma shaped vibrioforms from rod shaped bacilli or spherical cocci but you can't get detail.
Our confocals can give a bit...
A neg stain for Tem is about as simple as it gets - I spot a suspension of cells ( 10 microlitres ) onto an EM grid, leave for one minute and blot. Quickly dip into water and immediately blot ( removes much of the salt present in LB media ), then spot on the stain and blot after one minute...
It depends on what kind of images you need and what type of SEM. If it's an environmental sem you may not need any major sample prep as they're designed to run with wet sample. Otherwise your cells will need dehydrating which means fixing them first or they'll shrivel up, they then need a metal...