The Stack Overflow podcast is back! Listen to an interview with our new CEO.

New answers tagged

2

The "normal" (green here) arrowheads stand for a positive effect of the upstream factor or protein on the process or protein it points to. For instance, it means amino acids activate TORC1. Instead, arrows that end with a line (red here) stand for inhibition. For instance, rapamycin inhibits TORC1.


2

The blunt head arrow means inhibition i.e. suppression. i. e. A -----------| B means A suppressing B. the factor at the arrowhead is being supressed. The factor at arrowtail is an suppresor for the other factor. The pointed head arrow means activation or increasing activity. A -------------> B means A is increasing activity of B. Factor at ...


1

The reason why it's mostly referred to as basic is because the non-protonated nitrogen in the ring has a lone pair that it actively donates in several biochemical reactions. Lone pair donator = Lewis base


1

You could try methyl cellulose, which my lab and others use. It's not exactly an adhesive, but it is quite viscous. It's common enough that it's in the Zebrafish Book: https://wiki.zfin.org/display/prot/Methyl+Cellulose+Mounting . Obviously, be sure whatever you do is approved by your animal care and use committee.


3

Does the ingestion of alcohol, when taking (racemic) methylphenidate can actually make it more potent? It is the 2011 study you've mentioned that answers most of the question. In the study, ethanol co-ingestion with racemic MPH elevated maximal plasma levels of d-MPH by up to 40%. The participants reported greater stimulant effect after alcohol + MPH than ...


4

You would not expect the same enzyme from different tissues to have different Km values if the enzymes are truly identical. In addition, you would not expect the Km value to change during purification: the Michaelis constant for the purified enzyme should be the same as that determined with a crude sample. If this is not true, it might mean that the ...


2

Sort of. Proteins can enter the body through the intestines by exploiting a few transport mechanisms, They are not truly crossing the cell membrane but are transported across the cell in vesicles. Though not into the bloodstream but into the lymph system. M cells in particular will move antigens across the intestinal wall, a few more durable proteins (like ...


0

That's impossible, if it has to pass through your cells membrane , check this small protein of 3 amino acids (Garcia, A., Eljack, N. D., Sani, M. A., Separovic, F., Rasmussen, H. H., Kopec, W., ... & Clarke, R. J. (2015). Membrane accessibility of glutathione. Biochimica et Biophysica Acta (BBA)-Biomembranes, 1848(10), 2430-2436.) Although going ...


0

For most amino acids, the removal of the α-amino group involves α-ketoglutarate and glutamate. The amino group is first transferred to a-ketoglutarate by transaminases, and the resulting glutamate is then deaminated (via glutamate dehydrogenase) to yield ammonia. The same is true for amination. Glutamate and glutamine are the two major amino group-donors. ...


5

This is a question I also remember wondering about when I was younger in school. Now as a professional it's way too obvious to even explain. But i think it's an important and common question, which warrants an example or two from common daily lab practice. Preface You have to understand that DNA is a molecule. It's really tiny. It's not trivial to work ...


0

Both the sentence can be understood from the below explanation. In a newly synthesizing DNA strand, the DNA polymerase forms extensive hydrogen bonds with the newly added base everytime a new nucleotide is added. (First sentence) Polymerase also forms bonds with the DNA backbone of phosphate and sugar. (Second sentence) The first sentence talks of how ...


1

In order to set up an enzyme assay that allows quantitative kinetic analysis three key requirements come to mind: The assay should be sensitive A plot of velocity versus enzyme concentration should be linear and through the origin at both high and low substrate concentrations. The initial rate should be measured. Spectrophotometric Assays ...


2

Someone has already mentioned catalase and potatoes, but another way to do it would be to use hydrogen peroxide. The students could cut the potato up smaller to investigate the impact of surface area, heat/cool the mixture using a beaker with water in and a thermometer, and change the amount of potato used. So a few variations of conditions for a fairly low ...


-1

Catalase from blood. Prick your finger, collect a small amount of blood. Add some hydrogen peroxide to the blood, it will foam as the catalase decomposes the hydrogen peroxide. Obviously there are biohazard considerations when dealing with human blood. Some plants, notable horseradish also contain peroxidase if you wish to avoid pinpricks.


5

There is the classic potato starch/iodine/amylase experiment: http://dailynexus.com/2016-08-31/chemistry-101-the-classic-potato-iodine-blueblack-experiment-finally-has-an-explanation/ From memory, when you add iodine to a small piece of potato, the potato starch reacts to produce a dark blue/black colour. The amylase enzyme in human saliva can break down ...


Top 50 recent answers are included