QUESTION 13 Which of the following would be found in a person with a 46, XX kary

Question

QUESTION 13

Which of the following would be found in a person with a 46, XX karyotype with the SRY gene present? [Select all that apply]

Female external genitalia

Male external genitalia

Barr body

Low testosterone compared to 46, XY men without genetic mutations

Decreased fertility

1.75000 points   

QUESTION 14

Which of the following would be found in a person with a 46, XX karyotype with a SRD5A2 gene mutation? [Select all that apply]

Female external genitalia, before puberty

Male external genitalia, after puberty

SRY

Barr body

1.75000 points   

QUESTION 15

Which of the following would be found in a person with a 46, XX karyotype with an AMH or AMHR2 gene mutation? [Select all that apply]

Male external genitalia

Female internal anatomy

Male internal anatomy

SRY

Barr body

High testosterone

Female external genitalia

Male external genitalia

Barr body

Low testosterone compared to 46, XY men without genetic mutations

Decreased fertility

Explanation / Answer

QUESTION 13   

SRY gene: Sex determining region of Y. Also called Testis development factor.

SRY is located on the short arm of Y chromosome. It is the single most important factor determining the male sex of the fetus and it is expressed during 6-8 weeks of fetal development. Mutations give rise to XY females with gonadal dysgenesis. which is also known as sweyer syndrome.

Translocation of the part of the Y chromosome containing SRY to the X chromosome causes XX male syndrome.

So, according to the given question person is having female chromosomes i.e, 46 XX but there is also presence of SRY gene which indicates that some translocation have occurred between Y chromosome and X chromosome. This is a case of XX male syndrome with positive SRY. These individuals have external genitalia but usually smaller in size and have infertility.

Therefore among the given options, option 2-male external genitalia, option 4-low testosterone level compared to 46, XY men without genetic mutations and option 5-decreased fertility are correct.

QUESTION 14  

SRD5A2 gene: ( steroid 5 alpha reductase 2)

It is present on the short arm of chromosome 2 and is involved in the fornation of steoid 5-alpha reductase2. This enzyme is responsible for the conversion of the hormone testosterone to dihydrotestosterone , which is essential for the development of male sex chahracterstics.

Males having deficiency of this enzyme are genetically male but born with underdeveloped external genitalia and sometimes the genitals resemble to that of a female. During puberty the testes produce more testosterone and individuals start developing secondary male characterstics.

In females this gene is associated with polycystic ovary syndrome which leads to irregular menstruation, hirsutism acne etc.

In the given question the karyotype is of a femalei.e, 46 XX, having SRD5A2 gene mutation.Therefore among the given options, the option 1(female external genitalia, before puberty) seems to be a better answer after excluding other options.

QUESTION 15

AMH (anti mullerian) gene

During development of male fetuses the AMH protein is produced and relased by testes which do not allow the formation mullerian duct which is the precursor of female internal reproductive organs i.e, uterus and fallopian tubes. So in male fetuses this duct is degenerated by AMH gene wheras in female fetuses mullerian duct leads to the formation of uterus and fallopian tubes.

Therefore in the given question option 2- female internal anatomy is correct.

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