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Chapter 5: Specialized Eukaryotic Cells and Tissues

Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby admin » Fri Aug 27, 2010 1:33 am

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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby goldstanda3269 » Sat Sep 12, 2015 5:16 am

This spinal cord is mostly a collection of axons but there is also some supporting tissue and ganglia, which are collection of nerve cell bodies inside of the central nervous system where synapsis occurs.

This is moving far from the GAMSAT: http://faculty.spokanefalls.edu/InetSha ... age002.jpg
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby goldstanda3269 » Thu Nov 12, 2015 5:09 am

The 2 statements are not describing the same moment. They are describing 2 of 3 different phases that occur after an action potential begins: first, another AP is NOT possible (= absolute refractory period); second, another AP is possible with more stimulus (relative refractory period); third, an AP can occur normally.

You can see the absolute and relative refractory periods labelled onto the AP graph here: https://bradyonthebrain.files.wordpress ... -graph.gif
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby athman2626045 » Sun Nov 29, 2015 3:33 pm

Hi,

I am having trouble understanding the difference between membrane proteins - intrinsic proteins - peripheral proteins. This is an answer from the 2nd set of graph questions, question 4:

"However, unlike many soluble proteins, membrane proteins typically have very hydrophobic surfaces, which allows them to be embedded in the hydrophobic environment of lipid bilayers (remember, lipid bilayers are made up of two layers—the polar phosphate heads are on the outside surfaces, while the membrane interiors are made up of the lipid tails)."

Then this answer from the Q & A's of the generalised eukaryotic cell, question 2: "We would not expect a peripheral protein or the portion of an integral protein facing the extracellular fluid to be hydrophobic, because of the hydrophilic nature of the fluid (see Q1). This leaves us with answer choice B.; the interactions are likely to occur between a charged (hydrophilic) portion of the integral protein with the charged portion of the peripheral protein."

Any help would be appreciated.

Cheers
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby athman2626045 » Sun Nov 29, 2015 3:37 pm

Sorry! Regarding the above question, I was specifically asking about the difference in the two questions. They seem to be very similar about membrane proteins but give polar opposite answers? Pardon the pun.
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby athman2626045 » Sun Nov 29, 2015 3:49 pm

Another question.


6) The passage suggests that colchicine might act by:

A) disrupting mitotic spindle formation.
B) inhibiting DNA synthesis.
C) inhibiting the replication of chromosomes.
D) preventing the degeneration of the nuclear envelope.
Your Answer: D
Correct Answer: A

The passage describes colchicine effecting chromatid segregation in anaphase. So I don't understand why the answer is A (which occurs in prophase)??
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby goldstanda3269 » Sun Nov 29, 2015 8:21 pm

athman2626045 wrote:Sorry! Regarding the above question, I was specifically asking about the difference in the two questions. They seem to be very similar about membrane proteins but give polar opposite answers? Pardon the pun.


Very good pun!

It is very helpful to take a look at BIO-04 to see the image of the extrinsic (= peripheral) and intrinsic (= integral) proteins. You can see that the extrinsic portion, facing water, must be hydrophilic. You can see the portion of the intrinsic protein that is within the membrane, surrounded by fatty acid tails of phospholipids, must be hydrophobic (= fat loving = lipophilic).
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Re: Chapter 5: Specialized Eukaryotic Cells and Tissues

Postby goldstanda3269 » Sun Nov 29, 2015 8:46 pm

athman2626045 wrote:Another question.


6) The passage suggests that colchicine might act by:

A) disrupting mitotic spindle formation.
B) inhibiting DNA synthesis.
C) inhibiting the replication of chromosomes.
D) preventing the degeneration of the nuclear envelope.
Your Answer: D
Correct Answer: A

The passage describes colchicine effecting chromatid segregation in anaphase. So I don't understand why the answer is A (which occurs in prophase)??


I don't see that question in Chapter 5. Nonetheless, based on the information above, if the "passage describes colchicine effecting chromatid segregation", then one must question: "how are chromatids segregated?" Basically, this leads to the answer: interfering with microtubules and/or spindle formation. Note: although segregation only occurs in anaphase, segregation can only occur because of "tools" (= proteins) that were built by the cell during interphase, and to some degree, assembled in prophase/metaphase.

Note: The nuclear membrane breaks apart at the end of prophase. Also, the nuclear membrane has no role in chromatid segregation.
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