Answer:
Low phenylalanine concentration:
- If the enzyme is inactive, PAH will look like its inactive form, with phenylalanine located in the allosteric site / inactive site so that PAH is a different shape. This will not allow as much phenylalanine to be converted into tyrosine, as we wait for Phe levels to increase.
High phenylalanine concentration:
- If the enzyme is active, PAH will look like its regular form, with an open active site that's the size of phenylalanine so that reactions can occur. (Like a hand fitting into a glove, or a lock into a key.) Phenylalanine will be the substrate, the thing acted upon by the enzyme. This will eventually raise the amount of tyrosine that's created and lower the concentration of phenylalanine.
Think about it like this. Ever heard of homeostasis? That's how the body likes to be the same, keep everything regulated, all the time. So if there are high levels of something, the body is going to try to keep that something down, and if there are low levels, it's going to try to increase the concentration of that thing.
The correct answer is "escapable shock".
Seligman and Maier's experiment was focused on the psychological phenomenon of learned helplessness. The first phase of the experiment included three groups of dogs who were put in harnesses. Dogs from groups 2 and 3, were tied in pairs and received electric shocks at random times. Dogs from group 2 were trained to press a lever to stop the electric shock. When dogs from group 3 pressed a lever, there was no effect on the electric shock. Therefore, dogs from group 3 perceived the electric shock as an inescapable painful stimulus. The second phase of the experiment involved a shuttle box. Dogs from all groups were put in these boxes and were free to jump outside the box when the electric shock was applied. However, dogs from group 3 (who were trained in phase 1 to believe that this was an inescapable shock) were passive and did not make any effort to escape the box. This was an experiment proving the theory of learned helplessness, according to which an animal or human who is chronically exposed to painful and inescapable stimuli, is unable to try and escape from new painful situations.
"The differences in pre-mRNA splicing that results in an altered pattern of exon inclusion" is most likely to have contributed to this phenomenon.
<u>Option: C</u>
<u>Explanation:</u>
The expression of the eukaryotic gene requires several stages and can be regulated by several of them. Different genes are controlled at different locations and it is not unusual for a gene to be controlled at multiple steps, especially a significant or powerful one.
- In accessibility of Chromatin the chromatin structure includes DNA and can be regulated by its assembling proteins. More free or 'relaxed' chromatin allows a gene more transcriptible.
- For many genes transcription is a key regulatory point. Its factor protein sets bind to unique DNA sequences within or near to a gene and encourage or suppress its transcription into an RNA.
- It is possible to control the splicing, capping, and attaching a poly-A tail to an RNA molecule, and thus exit the nucleus. Specific mRNAs might be produced by alternative splicing from the same pre-mRNA.
Chlorophyll, which gives plants their green color, enables plants to turn sunlight, CO2, water, and a few minerals into new plant tissue through a process called photosynthesis<span>.</span>
