Destroyer Bio Questions

[au5233]

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Hey Guys,

so I have some more bio questions from destroyer maybe someone can help me on? If not, I will have to give Dr. R a good ol' phone call...

#241: Ok I see what he is saying, But couldn't you look at it this way: Since organism X has the highest metabolic rate, it obviously has the highest O2 demands. So at low atmospheric pressures, such as at 20 torr on the graph, its hemoglobin will show the highest affinity for O2 to meet its metabolic demands and thus the most saturation? Because I remember someone had posted on here (the one girl who got like 99% on every section) animals like elephants and llama have the highest O2 affinities on their Hb because of large body size and high living altitudes. So i tried to use that logic on this problem...but my answers are reversed =(

#246. In the solution, he says Vmax is unchanged in competitive inhibition, but decreases in noncompetitive inhibition...I can't seem to make sense of this. If both are affecting the enzymes activity, just one is binding to the active site and the other is binding somewhere else on the molecule, but BOTH are preventing the enzyme from catalyzing its reaction...then how does Vmax change for one and not the other?

#254. I dont know if this is an anal question, but I am assuming fine details is important when taking the DAT. So with that said, how is answer (a) considered true? Fetus' don't use their longs to breath O2, they get it from the placenta. However INFANTS do use their lungs...sooo should he have worded that answer differently to be correct?

#260. Finally the slide question. OK so RBC = no nucleus and no mitochondria. Is this picture showing a mitochondria IN a cell sample? And if so, I see that he says a cardiac muscle has more mitochondria, BUT regardless of the number of mitochondria, liver, pancreas, appendix, and heart muscle all have them, so this sample could be from any one of them, could it not?

Oh and 271: if the promoter is where RNA poly binds to start transcription, then why exactly is choice (b) wrong??

Alright guys, any input would be awesome. Let me know if you have any questions either!

Thanks

M

 

[TheWiredNerv]

#246 Vmax is unchanged because the substrate that is competeing against the other substrate is still binding to the active site of the enzyme. This binding will cause Vmax too remain the same. Here is an example. You have a big that can fit 3 apples. However, you put 3 oranges in it instead. It is still holding 3 objects.

For noncompetitive inhibition, Vmax is decreased because another ligand is binding to a site other than the active site. The inhibitor causes a conformational change and doesn't allow the substrate to bind to the active site. That is why Vmax changes for noncompetitive inhibition and remains the same for competitive inhibition.

#260: You have the greatest chance of finding a mitochondria in the cardiac muscle.

I can't really answer the others as I let my friend borrow my Destroyer for her studying.

 

[predentlsu1]

On #241...you are interpreting the graph wrong.
In an animal with a high oxygen demand, hemoglobin does not want to hold onto the oxygen...it wants to off load it at the tissues therefore hemoglobin would have a lower affinity for O2. On the graph the lowest curve #3 represents an animal with a higher need for oxygen than curve #1. So yes at a low atmoshpheric pressure the animal in #3 is going to have a very high oxygen demand but the hemoglobin does not have a high affinity for O2....it wants to dump it at the tissues as fast as it can to facilitate the oxygen debt the animal is experiencing. Let me know if that helps....it can be kinda confusing and I dont know if I explained it very well.

 

[predentlsu1]

#260 If you look above the picture the quesion states...."A certain cell was viewed under the microscope to reveal SEVERAL THOUSAND of the below structure:" Or my book says that anyways......but that is the key to the question, many mitochondria are found in areas of high energy requirements such as muscles.

 

[predentlsu1]

#271 I am pretty sure that a promoter site is not the start site for DNA transcription. The promoter sequence ususally lies upstream of the start site and is a place that RNA pol binds. Once RNA pol binds to the promoter site the gene is ready for transcription...and this occurs when it comes across the initiation or "start" site which is usually a TATA box. I think this is right but someone correct me if I am wrong.