Biology Questions and Answers
- Is it more indicated for a
geneticist desiring to map the
X chromosome of the mother
of a given family (the
researcher does not have
access to her DNA, only access
to the genetic material of the
offspring) to analyze the
chromosomes of her
daughters or of her sons?
To analyz(assuming no accesse the X DNA o to her ownf a mother
material) it is more indicated to study
the genetic materialX chromosomes of males com of her sons since e from thalle
mother while the daughters have X
chromosomes ffrom the father. By rrom thesearchine mother andg the (^)
material of the sons it is ensured that
the studimother.ed X chromosome is from the
- Do the genes of the X and Y
chromosomes determine only
sex characteristics?
Besides sex genes the sexchromosomes have also autosomal (^)
genes, genes that codiproteins related to nonsexual traits.fy several
- What are the main diseases
caused by errors of the
number of sex chromosomes
in the cells of an individual?
Diseases caused by abnormal number of
sex chromosomaneuploidies. es are called sexThe main sex XXX, or trisomy X (womaneuploidies aren whose e: 44 +cells (^)
have an additional X chromosome); 44
- XXY, or Klinefelter's syndwhose cells have an extra Xrome (men
chromosome); 44 + XYY, or double Y
syndrome (men whose cells have anadditional Y chromosome); 44 + X,
Turner’s syndrome (women whose cells
lack an X chromosome).
- What is the inactivation of
the X chromosome? What is a
Barr body?
Inactivationphenomenon that occurs i of the X chromosomn wome is aen.
Since women have two X chromosomes
only one of them remains active anfunctional mixed to the chromatin wdhile (^)
the other remains condensed and
inactive.
In the same woman in some cell
lineages the functionalthe one from the father X chromosomand in other celle is (^)
lineages the functional chromosome is
the X from thcondition known as mosaicisme mother characterizin (relateg ad
to the X chromosome).
Under the microscope the inactive X
chromosome generally in the periphery of theis seen as a granule
nucleus. This granule is called the Barr
body.
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