How would you answer this Biology question?

[dancerdoc89]

Which of the following properties of the red blood cell allows it to complete its course through the circulation?

a. lack of a nucleus
b. lack of protein production
c. lack of a structural protein network
d. lack of cholesterol in the cell membrane

...I'm down to two possible answers and can support both of them...which answer would you choose and why??

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[vayntraubinator]

Which of the following properties of the red blood cell allows it to complete its course through the circulation?

a. lack of a nucleus
b. lack of protein production
c. lack of a structural protein network
d. lack of cholesterol in the cell membrane

...I'm down to two possible answers and can support both of them...which answer would you choose and why??

Lack of protein structural network so that it can make it through the small width of the capillaries.

 

[HelloNicky]

I choose A. The lack of nucleus gives red blood cells their biconcave shape which allows oxygen to diffuse through the cells better.

Edit: Then again, Vay's answer applies more to the question asked.


Edit 2: Read these. One of the links will give you the answer whether it is A or C. The other link is just informative.
http://articles.latimes.com/2011/jan/10/news/la-heb-fake-blood-cell-20110110
http://www.britannica.com/EBchecked/topic/192088/red-blood-cell

 

[vnicolas]

C

 

[dancerdoc89]

Thanks for your answers/references....the apparent answer is A...the exact two that I chose were A and C for the reasons you guys mentioned. I swear this is the case for the many practice MCAT questions that I've gone through in BS sections...ugh!

btw, this question is from Kaplan...dunno if that carries any rhyme or reason for the uncertainties

 

[kkentm]

does a red blood cell actually lack a protein network? wouldnt that result in a cell being of no consistent shape since there is no structural support? i figure since red blood cells have a consistent biconcave shape they must have some type of structurally supporting mechanism

 

[dancerdoc89]

does a red blood cell actually lack a protein network? wouldnt that result in a cell being of no consistent shape since there is no structural support? i figure since red blood cells have a consistent biconcave shape they must have some type of structurally supporting mechanism

Ok, I would think it must have some sort of structural network...however I would think that network would have to be established before the nucleus disappears...you need the DNA to transcribe/translate proteins that the cell needs. So, I think saying that a RBC lacks a protein network is pushing it.

However, I recall that not having such a prominent protein network (i.e. microfilaments) give the RBC flexibility so it can fit through capillaries (as someone else mentioned before)

 

[kkentm]

^ can you post Kaplan's answer explanation for us? that would be nice

 

[dancerdoc89]

^ can you post Kaplan's answer explanation for us? that would be nice

I would if I could...I actually copied the letter answers only b/c this particular practice test expired, so I cannot access it online anymore. I have the questions/passages/letter answers copied (more like print-screened) but not the explanations.

I know, it does us no good. My apologies!

Even so, I wanted to see how people have different instincts (and support) about answering a given MCAT question...and this was one of them.

 

[TieuBachHo]

The answer is A:

The red blood cells actually has structural protein network embedded in its membrane. It helps to maintain its structural integrity, elasticity, and also to prevent premature-SELECTIVE senescence.

 

[whiteshadodw]

The answer is A:

The red blood cells actually has structural protein network embedded in its membrane. It helps to maintain its structural integrity, elasticity, and also to prevent premature-SELECTIVE senescence.

i agree. B and C basically say the same thing, while D doesn't exactly make sense. cholesterol makes things more flexible, not less.

 

[AlphaMagnum]

i agree. B and C basically say the same thing, while D doesn't exactly make sense. cholesterol makes things more flexible, not less.

Cholesterol makes things less flexible? In my Biochem and Molecular Biology courses, I was taught that cholesterol, when inserted into cellular membranes, makes them more rigid...

 

[whiteshadodw]

Cholesterol makes things less flexible? In my Biochem and Molecular Biology courses, I was taught that cholesterol, when inserted into cellular membranes, makes them more rigid...

you must have learned wrong and read what i wrote wrong. cholesterol interacts with fatty acids so they are less likely to freezing. the fatty acids are not as prone to becoming crystalline with higher cholesterol levels.

from wiki:
"Cholesterol is required to build and maintain membranes; it modulates membrane fluidity over the range of physiological temperatures."

 

[salim271]

you must have learned wrong and read what i wrote wrong. cholesterol interacts with fatty acids so they are less likely to freezing. the fatty acids are not as prone to becoming crystalline with higher cholesterol levels.

from wiki:
"Cholesterol is required to build and maintain membranes; it modulates membrane fluidity over the range of physiological temperatures."

^This is right, cholesterol acts in a similar way that a double bond in a fatty acid would, it causes kinks and therefore reduces the amount of stacking and londons interactions the membrane FAs can do, increasing fluidity.