Week 4 - The Chromosomal Basis of Inheritance Flashcards
What gene on what chromosomes codes for the development of male anatomical features?
The SRY gene on the Y chromosomes
What happens to female X chromosomes during embryonic development?
In each cell, randomly, one of the X chromosomes will inactivate and condense into a Barr body.
What is a barr body?
During embryonic development in females, one of the X chromosomes is randomly deactivated, forming a Barr body
What are linked genes?
The physical location of two or more genes found of the same chromosome is called linkage.
How do linked genes relate to the law of independent assortment?
Linked genes are always transmitted together, thus violating the law of independent assortment.
How can geneticists predict if genes are linked using a testcross?
Using a homozygous recessive pairing, if the offspring differ from the 1:1:1:1 ratio, then linkage is likely
What is aneuploidy?
Deviation from the usual chromosome number
What is polyploidy?
More than 2 complete chromosome sets (e.g. triploidy, tetraploidy)
What is polysomy?
More than 2 copies of a particular chromosome in a diploid cell
What is monosomy?
Only one copy of a particular chromosome in a diploid cell
What is trisomy?
Three copies of a particular chromosome
What is trisomy 21?
Down Syndrome
What chromosomal alteration causes Down Syndrome
Trisomy 21 (extra chromosome 21)
What is Klinefelter’s Syndrome?
A condition where the child is born with an extra X chromosome
What is the karyotype 47 XXY?
Klinefelter’s Syndrome
What is Turner’s Syndrome?
A condition where a child is born with only 1 X chromosome.
What is the karyotype 45 XO?
Turner’s syndrome
What is the karyotype for Turner’s Syndrome?
45 XO
What is the karyotype for Klinefelter’s Syndrome?
47 XXY
What are the 4 alterations/deviations of chromosome structure?
Deletion = removes chromosomal segment Inversion = reverses a chromosome segment Duplication = repeats a chromosome section Translocation = moves a section from one chromosome to a non-homologus chromosome.
What is Cri Du Chat Syndrome?
A disorder resulting in mental impairment and leaves the child with a cat-like cry
What is the karyotype 46, (5p-)?
Cri Du Chat Syndrome
What is the karyotype for Cri Du Chat Syndrome?
46, (5p-)
