EK 1001 q 36

[capn jazz]

Which of the following properties is unique to oxytocin?

a) it has a quaternary structure
b) it has a tertiary structure
c) it has a secondary structure
d) it has a primary structure

The answer is D. Am I alone in thinking this is an ABSURDLY worded question?? If the wording were "its primary structure", that would make 100% sense. But uh, it is not unique to HAVE a primary structure.

Will questions on the actual MCAT be worded so terribly??

/end rant.

---

Members don't see this ad.

 

[JasoniusUW]

Don't think so. I'd think the AAMC will have more peer review than a private company.

 

[engineeredout]

You're right, its a terrible question. Simply having a primary structure is certainly not unique

 

[neil100]

actually this question is fair for the MCAT despite what you think.

The question is testing the concept of the types of hormones.

First you have to recognize that Oxytocin is a hormone. Then you also have to know that it is a peptide hormone based on the answer choices. (none of them are suggest that the hormone is steroidal) Then you have to realize that most of the peptide horomones (epi, vasopressin, norepi, oxytocin, etc.) usually consist of pretty small peptides (around 10-20 amino acids). Hence the structure is going to be a primary one or linear. There won't be a secodanry (or any structure beyond that) because it is not big enough to fold/make bonds to produce any other structure. So, the possible and reasonable choice is the linear or primary structure. This question does an excellent job of testing the concept of hormones, specifically the types of hormones and integrating that into protein structure knowledge.

Also, I believe the wording could be a bit better. More like which of the following structure does the oxytocin hormone have? But, I am pretty sure they are trying to test the concept of the types of hormones. (peptides are almost always primary structure for the reasons I gave above).

 

[VanBrown]

or it could be a basic biochemical question if it is worded half-decently. the AAMC will probably make sure the answers aren't "it has a xxx."

Going back to what you know about the different degrees of organization, which of the 4 are truly UNIQUE to any given molecule (oxytocin or otherwise)?

The answer is the primary structure. Many proteins have alpha-helices or beta-sheets 2ndary. Many proteins are either globular or structural 3rd. Many proteins have multi-domain structures.

What truly defines any protein is it's primary structure (i.e. its AA sequence).

The other three levels of structural organization are motifs/patterns which are common amongst proteins.

 

[0Complications]

actually this question is fair for the MCAT despite what you think.

The question is testing the concept of the types of hormones.

First you have to recognize that Oxytocin is a hormone. Then you also have to know that it is a peptide hormone based on the answer choices. (none of them are suggest that the hormone is steroidal) Then you have to realize that most of the peptide horomones (epi, vasopressin, norepi, oxytocin, etc.) usually consist of pretty small peptides (around 10-20 amino acids). Hence the structure is going to be a primary one or linear. There won't be a secodanry (or any structure beyond that) because it is not big enough to fold/make bonds to produce any other structure. So, the possible and reasonable choice is the linear or primary structure. This question does an excellent job of testing the concept of hormones, specifically the types of hormones and integrating that into protein structure knowledge.

Also, I believe the wording could be a bit better. More like which of the following structure does the oxytocin hormone have? But, I am pretty sure they are trying to test the concept of the types of hormones. (peptides are almost always primary structure for the reasons I gave above).

I can see your logic, but the answers tell you it is a peptide hormone, so that doesn't require any deduction.I agree with you that it is the length of the peptide chain, and I suppose they say it is unique because many others have longer chains, such as LH with 121, etc.

I agree with the original poster though. The question sucks. After reading it I just got a flashback to when I saw that question for the first time. I mean, is it really unique? Both ADH and Oxytocin the two posterior pituitary hormones are very small. It just sucks that the question leads you into believing it is something unique about about oxytocin. Plus, it makes you start to question, ok are they talking about a zymogen component or the active form.

OP, I wouldn't sweat it. Learn from it and move on, but yes it does suck. 👎

 

[0Complications]

or it could be a basic biochemical question if it is worded half-decently. the AAMC will probably make sure the answers aren't "it has a xxx."

Going back to what you know about the different degrees of organization, which of the 4 are truly UNIQUE to any given molecule (oxytocin or otherwise)?

The answer is the primary structure. Many proteins have alpha-helices or beta-sheets 2ndary. Many proteins are either globular or structural 3rd. Many proteins have multi-domain structures.

What truly defines any protein is it's primary structure (i.e. its AA sequence).

The other three levels of structural organization are motifs/patterns which are common amongst proteins.

👍 Now this is an explanation I would invest in. 🙂

 

[rocketbooster]

this question is a terrible one and would never be on the MCAT. as someone who has taken the real thing twice, i can assure you there will not be bull**** questions like that on your test.