When the S. cerevisiae genome was sequenced and surve...

Question

When the S. cerevisiae genome was sequenced and surveyed for possible genes, only about 40% of those genes had been previously identified in forward genetic screens. This left about 60% of predicted genes with no known function, leading some to dub the genes fun (function unknown) genes. You wish to know the physical location of the encoded protein product. How will you obtain such information?

Accepted Answer

Hi, everyone. Let's look at our next question. It says which method involves isolating different cellular compartments from yeast cells to analyze the presence of the protein of interest in each fraction. Choice A amino fluorescence microscopy B, subcellular fractionation, C protein tagging and protein protein interaction studies or D biochemical methods. Well, when I look over my answer, choices, I'm going to go ahead and eliminate choice d biochemical methods right away. It's a really generic term and we're clearly looking for a specific term describing a very specific technique. So we'll just toss that one aside and we know we're looking for something that will isolate or separate cellular components. So at the subcellular level, and then you're going to analyze fractions. Well, even if we don't remember the name right away, that would lead us pretty clearly to choice B subcellular fractionation. You're talking about, you've got subcellular in there and you're looking at fractions of something. And indeed, this is the technique we would look for. It involves disrupting the cells. So breaking up their cell walls, creating a sort of cell soup. And then using various centrifugation steps to separate the components by size density or other physical characteristics. So we're gonna separate our cell stew into fractions composed of say the organelles or other subcellular structures. And then we look at those fractions and analyze them for the presence of your protein of interest. So you then you can look at where in the cell which structures contain the protein. I'm looking for. We'll just take a quick look at our other remaining answer. Choices. A immunofluorescence microscopy would involve tagging a protein with a fluorescent marker and then looking at cells under a microscope, seeing where they fluoresce. But that doesn't involve looking for fractions of yeast cells and analyzing those fractions in microscopy. You're looking at intact cells under a microscope. So choice A is not our correct answer and then choice C protein tagging and protein protein interaction studies. Again, that would involve tagging your specific protein and seeing what it does, what it interacts with other proteins, not breaking up my cells and then looking to see which type of structures the protein is located in. So choice C is just not the correct description of the technique we're looking for. So again, which method involves isolating cellular compartments to analyze the presence of the protein of interest in fractions. Choice B subcellular fractionation. See you in the next video.

Key Concepts

Gene Function and Annotation

Protein Localization Techniques

Bioinformatics Tools

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