Human Genetic Disorders

" Sperm are like Beer, Eggs are like Wine !! "

" So that's how you make a Klingon "

Karyotype - A picture of a persons 23 pairs of chromosomes.

          Autosomal chromosomes - The first 22 pairs of chromosomes.

          Sex chromosome - The last pair of chromosomes.

Nondisjunction - Where chromosomes fail to separate properly during gametogenesis 1 and/or 2 and is the cause of too many or too few chromosomes.

          Y chromosome - Small chromosome only males have it.

          X chromosome - Large chromosome - Both sexes have it.

                    Barr body - In females, an inactive X chromosome.

X-linked traits - Genes that are carried on the X chromosome - males can only have 1.

          Hemophilia - X-linked Recessive disorder - can't clot your blood.

          Color blindness - X-linked Recessive disorder - can't see colors like red and green.

Sex-influenced traits - Beards, and Breasts - Your phenotype depends on your sex (whether you make testosterone).

          Male pattern baldness - Sex-influenced - Your phenotype depends on your sex.

Amniocentesis - 12th week push a needle into the uterus and take a sample of amniotic fluid with cells in it

Chorionic villus sampling   CVS - Takes a group of cells from part of the placenta - Earlier results

Screening eggs - A Preovulatory egg (only completed meiosis 1 - split homologous chromosomes) is removed and tests are done on the polar body.


Color blindness is X-linked -- Possible Genotypes:

         XBXB = Female with normal color vision

         XBXb = Carrier female with normal color vision

         XbXb = Female who is color blind

         XBY = Male with normal color vision

         XbY = Male who is color blind


Sex-Influenced traits - Beards, Breasts, and Baldness

                       Males          Females

               BB = Normal         Normal

               Bb = Bald              Normal

               bb = Bald               Bald























































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Last updated on 4 January 2018