2 a picture of someone’s chromosomes Karyotypesa picture of someone’s chromosomesCentromere
3 Banding Pattern “Bands” are large segments of DNA **Remember what chromosomes are made up of
4 Chromosome Pair #23 determines sex Exception: Position 23Chromosome Pair #23 determines sex
5 Female 23rd pair of chromosomes are homologous Both chromosomes are “X” chromosomesX
6 Male 23rd pair of chromosomes are NOT homologous One chromosome is “X” and the other is a “Y” chromosome
7 DisjunctionNormal separation of Chromosomes and Chromatids during Meiosis I and Meiosis II (Anaphase I & II)
8 Has 46 chromosomes for humans Normal KaryotypesHas 46 chromosomes for humansArranged in 23 pairs
9 Failure to separate homologous pairs NON-disjunctionNondisjunction during Meiosis IMetaphase IAnaphase IFailure to separate homologous pairs
10 Failure to separate Chromatids NON-disjunctionNondisjunction during Meiosis IIMetaphase IIFailure to separate ChromatidsAnaphase II
11 What does nondisjunction cause? Missing Chromosomes – MonomyEmbryo/Fetus will not surviveMeans 45 chromosomesException is this can occur on 23rd chromosome pairExtra Chromosomes – TrisomyMeans 47 chromosomesDown Syndrome (Trisomy 21)Patau Syndrome (Trisomy 13)Klinefelter’s Syndrome (XXY)Turner’s Syndrome (X-)XYY SyndromeAnd many more………….
13 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
14 Klinefelter’s Syndrome (XXY) Extra Sex Chromosome “X”
Your consent to our cookies if you continue to use this website.