More Bio Questions

[datgirl1]

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Some bio questions from Achiever:

1) If the centrioles of an oocyte are destroyed, what does this affect?
The correct answer to this question was that it would have no affect because centrioles are not needed for cell division, even though it makes it more efficient. I thought the answer would be that it affects formation of spindle microtubules. Which answer is right?

2) What proves that mitochondria evolved from prokaryotes?
Answer is that they have their own unique DNA. I thought the answer would be that they produce their own energy.

3) The difference between fast block polyspermy (acrosome rxn) and slow block polyspermy (coritical rxn) is that fast block depolarizes the membrane, whereas slow block creates the fertilization membrane. Any other difference between the two? And do both of these occur in mammals?

 

[FeralisExtremum]

1) If the centrioles of an oocyte are destroyed, what does this affect?
The correct answer to this question was that it would have no affect because centrioles are not needed for cell division, even though it makes it more efficient. I thought the answer would be that it affects formation of spindle microtubules. Which answer is right?

This is a bit tricky. Achiever is technically correct, in that recent experiments have shown you can still form the mitotic spindle (which is critical for cell division) without centrioles. I think it is unlikely the DAT is testing to this level of recency and specificity. The understanding of most college students from their general biology courses is going to be that the centriole is used in mitotic spindle formation (and thus critical for cell division), and I believe that will be the answer the DAT is looking for if it were to test such a topic.

2) What proves that mitochondria evolved from prokaryotes?
Answer is that they have their own unique DNA. I thought the answer would be that they produce their own energy.

Producing their own energy wouldn't be definitive proof of evolution from prokaryotes (it's a trait unique to mitochondria and chloroplast but it doesn't actually give you any information about their origin). Having their own unique DNA would be - it supports the endosymbiotic theory (which suggests that the mitochondria and chloroplasts of eukaryotic cells originated as prokaryotic cells that were taken up into a host cell). This is a pretty important theory to know for the DAT. The evidence in support of this theory (specifically that these organelles were originally prokaryotic in origin) would be the mitochondria and chloroplast having circular DNA that is not wrapped in histones (like prokaryes), independent reproduction of these organelles in a process similar to binary fission (like prokaryotes), two membranes (suggesting they had their own membrane and became double membraned when they were engulfed by the host cell), etc. Endosymbiotic theory is also sometimes known as symbiogenesis.

3) The difference between fast block polyspermy (acrosome rxn) and slow block polyspermy (coritical rxn) is that fast block depolarizes the membrane, whereas slow block creates the fertilization membrane. Any other difference between the two? And do both of these occur in mammals?

Here is a good video that recaps the critical parts of slow and fast block:


Fast block tends not to be seen in mammals, but slow block is.

 

[FLMermaid]

OMG! OP, I like Achiever too!!!