Chromosomal mutations Karyotypes& Chromosomal mutations

1. Karyotype – A picture of all of an organisms chromosomes. *Doctors can use karyotypes to check for chromosomal abnormalities.

2. Mutation – A change in the DNA. Point (Gene)mutation – affects a single nucleotide. May be a substitution, insertion or deletion. Frameshifts are caused by insertions and deletions.

3. Chromosomal Mutations – Changes in the DNA involving more than a single nucleotide. Gene duplication – During meiosis, when crossing over should occur, the chromosomes are not aligned properly and and one chromosome may end up with two copies of one gene.

b. Translocation – A piece of one chromosome moves to a nonhomologous chromosome.

c. Deletion – Due to breakage, a piece of a chromosome is lost.

d. Inversion- A piece of a chromosome breaks off, flips around and reattaches in the same location.

e. Nondisjunction – When homologous chromosomes fail to separate during meiosis I or when sister chromatids fail to separate during meiosis II. Meiotic nondisjunction Flash http://www.biostudio.com/d_%20Meiotic%20Nondisjunction%20Meiosis%20I.htm

Edward Syndrome

Newborns with Patau syndrome typically present in the neonatal period with low Apgar scores and may have the following conditions: -Cleft lip -Cleft palate -Polydactyly (postaxial) -Microcephaly -Rocker-bottom feet -Microphthalmia -Scalp defects (cutis aplasia) -Hernias -Neural tube defects *Most only survive a few days.