Presentation on theme: "Nondisjunction Homework for 11/13/14"— Presentation transcript:
1 Nondisjunction Homework for 11/13/14 Fill out notes on the back of page 34, which is the Cell Division Venn Diagram
2 NondisjunctionAlthough the events of meiosis usually proceed accurately, sometimes an accident occurs and the chromosomes fail to separate correctly. This is known as nondisjunction.
3 NondisjunctionThe zygote that has been created will have an extra or missing chromosome. This would result in an inherited genetic disorder.In most cases, the presence of an additional chromosome or missing chromosome results in the death of the zygote.
4 NondisjunctionMonosomy - the presence of only one chromosome from a pair in a cell's nucleus.Trisomy – the presence of three chromosomes instead of 2 in a cell’s nucleus.
5 KaryotypesWhen you are born, doctors take a sample of your blood and create a karyotype. This will enable the doctor to see if you have any additional or missing chromosomes.A karyotype is a standardized arrangement of all the chromosomes of a cell.
6 KaryotypesHomologous chromosomes are paired up, then they are put in order from the LARGEST chromosome pair to the smallest.
7 Karyotypes2 x chromosomes=GIRLautosomessex chromosomes
8 Karyotypes Everything okay here?? What gender?? 2 different sized sex chromosomes = male
9 Down’s syndrome Everything okay here?? trisomy 21 trisomy 21 decreased muscle tone at birthasymmetrical or odd-shaped skullround head with flat area at the back of the headslanting eyessmall mouth with protruding tonguesingle crease on the palmslowed growth and developmentdelayed mental and social skillstrisomy 21trisomy 21
10 Turner’s syndrome Everything okay here?? monosomy X monosomy X short stature (affects almost all girls with Turner, to different degrees)failure of ovaries to develop (90-95% of girls)webbed neck (25%) or short neck (40%)abnormal fingernails and toenails (70%)hearing disorders (50-90%)frequent ear infections in childhood (75%)monosomy Xmonosomy Xmonosomy X
13 Kleinfelter’s syndrome No symptoms - some men are unaware they have an extra chromosomeEnlarged male breasts - only severe in about 10% of casesSparse facial hairSparse body hairInability to produce spermTallness - more likely to be taller than non-XXY males.ThinnessNormal intelligenceLanguage impairmentDelayed languageXXYXXY