Section Bank B/B #51

[laczlacylaci]

From the passage, it says that FSH is s peptide hormone.
Why is D incorrect? I remember reading that all peptide hormones are derived from tyrosine. (this sounds pretty extreme though)
1. Why is B incorrect? is it plasma membrane of blood vessel, and not endocrine cell.

2. Since FSH is hydrophilic, it would be secreted from the endocrine cell and diffuse into the blood vessel. On the other hand, a steroid hormone would need a carrier protein to enter the blood vessel, correct?

3. Are peptide hormones always hydrophilic? (this sounds pretty extreme too...)

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[rhinzaz]

Hi,

From the passage, it says that FSH is s peptide hormone.
Why is D incorrect? I remember reading that all peptide hormones are derived from tyrosine. (this sounds pretty extreme though)
1. Why is B incorrect? is it plasma membrane of blood vessel, and not endocrine cell.

2. Since FSH is hydrophilic, it would be secreted from the endocrine cell and diffuse into the blood vessel. On the other hand, a steroid hormone would need a carrier protein to enter the blood vessel, correct?

3. Are peptide hormones always hydrophilic? (this sounds pretty extreme too...)

FSH is a peptide hormone. True.

D is incorrect because FSH is NOT derived from a single amino acid. FSH is a "peptide", meaning it contains a string of amino acids. Also note that it does not consist of 'purely tyrosine' as that's what may you be confused about. This relates back to protein synthesis.

B is incorrect because FSH is too large (and potentially polar) to cross the plasma membrane of the endocrine cell (ant. pit) through diffusion. This relates back to membrane dynamics.

Steroid hormone would need a carrier protein to enter the blood vessel. Correct, it does not dissolve in blood (aqueous).

Yes, all peptide hormones (for knowledge of MCAT) are considered to be hydrophillic, and all steroid hormones are considered hydrophobic.

Finally, you may have confused peptide hormones with amine hormones (e.g epinephrine) which ARE derived from single amino acids (tyrosine).

 

[laczlacylaci]

Hi,



FSH is a peptide hormone. True.

D is incorrect because FSH is NOT derived from a single amino acid. FSH is a "peptide", meaning it contains a string of amino acids. Also note that it does not consist of 'purely tyrosine' as that's what may you be confused about. This relates back to protein synthesis.

B is incorrect because FSH is too large (and potentially polar) to cross the plasma membrane of the endocrine cell (ant. pit) through diffusion. This relates back to membrane dynamics.

Steroid hormone would need a carrier protein to enter the blood vessel. Correct, it does not dissolve in blood (aqueous).

Yes, all peptide hormones (for knowledge of MCAT) are considered to be hydrophillic, and all steroid hormones are considered hydrophobic.

Finally, you may have confused peptide hormones with amine hormones (e.g epinephrine) which ARE derived from single amino acids (tyrosine).

Thanks for clearing up the confusion!