9 DisjunctionNormal separation of Chromosomes and Chromatids during Meiosis I and Meiosis II (Anaphase I & II)
10 Failure to separate homologous pairs NON-disjunctionNondisjunction during Meiosis IMetaphase IAnaphase IFailure to separate homologous pairs
11 Failure to separate Chromatids NON-disjunctionNondisjunction during Meiosis IIMetaphase IIFailure to separate ChromatidsAnaphase II
12 What does nondisjunction cause? Missing Chromosomes – MonomyEmbryo/Fetus will not surviveMeans 45 chromosomesException is this can occur on 23rd chromosome pairTurner’s Syndrome (X-)Extra Chromosomes – TrisomyMeans 47 chromosomesDown Syndrome (Trisomy 21)Patau Syndrome (Trisomy 13)Klinefelter’s Syndrome (XXY)XYY SyndromeAnd many more………….
14 Trisomy 13 – Patau Syndrome Extra Chromosome 13Symptoms can includeCleft lip or palateClose-set eyes -- eyes may actually fuse together into oneDecreased muscle toneExtra fingers or toesHerniasHole, split, or cleft in the irisLow-set earsMental retardationScalp defects (absent skin)SeizuresSingle palmar creaseSkeletal (limb) abnormalitiesSmall eyesSmall headSmall lower jawUndescended testicle
15 Klinefelter’s Syndrome (XXY) Extra Sex Chromosome “X”
17 XYY SyndromeXYY syndrome is characterized by an extra copy of the Y chromosomemales with this condition may be taller than averageThis chromosomal change typically causes no unusual physical featuresMost males with XYY syndrome have normal sexual development and are able to father children
18 Jamie Lee Curtis XY male with Androgen Insensitivity Syndrome (AIS) resistant to androgensthe hormones responsible for male sexual development