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Published byGladys Richard
Modified over 5 years ago
Nondisjunction Nondisjunction—When chromosomes fail to separate during meiosis. This can happen at anaphase I or II.
Human male karyotype, written as 46 XY
Human female karyotype, written as 46 XX
Down Syndrome 47, XX or XY, +21
Down Syndrome 1 in 700 births 47 chromosomes XY or XX#21 Trisomy Nondisjunction
Down Syndrome Short, broad hands Stubby fingers Mentally retardedSmall round face Protruding tongue Shorter lifespan Slanted eyes
Patau syndrome 47, XX or XY, Trisomy 13
Patau’s Trisomy Syndrome1 in 10,000 births 47 chromosomes XY or XX 47, +13 #13 Trisomy Nondisjunction
Patau’s Trisomy SyndromeSmall head Small or missing eyes Heart defects Extra fingers Abnormal genitalia Mentally retarded Cleft palate Most die before birth; some survive a few weeks after birth
Edwards Syndrome 47, XY, +18
Edward’s Trisomy Syndrome1 in 2500 pregnancies, 1 in 6000 births 47 chromosomes XX=80% XY=20% #18 Trisomy Nondisjunction
Edward’s Trisomy SyndromeSmall head Mentally retarded Internal organ abnormalities 90% die before 5 months of age
No abnormal appearance/behavior fertileJacob’s syndrome XYY No abnormal appearance/behavior fertile
Jacob’s Syndrome 1 in 1,000 boys 47 chromosomes XYY only#23 Trisomy Nondisjunction
Jacob’s Syndrome Normal physically Normal mentallyAssociated with risk of learning disabilities. Once thought to be more aggressive Normal lifespan
Klinefelter’s SyndromeXXY, male
Klinefelter’s Syndrome1 in births 47 chromosomes XXY only #23 Trisomy Nondisjunction
Klinefelter’s SyndromeScarce beard Longer fingers and arms Sterile Low testosterone Delicate skin Possible learning disabilities Normal lifespan More X chromosomes could cause worse symptoms (XXXY)
Turner Syndrome 45, X
Turner Syndrome Occurs in about 1 in 2,500 birthsMany do not survive to birth No menstruation No breast development No hips Broad shoulders and neck
Trisomy X 47 XXX symptoms healthy and fertile - cannot be distinguished from normal female except by karyotype
Triple X Syndrome 1 in 1,000 births 47 chromosomes XXX only#23 Trisomy Nondisjunction
Genetic Disorders Autosomal and Sex-linked. HOW DO WE GET GENETIC DISORDERS? Nondisjunction – failure of chromosomes to separate during cell division.
Karyotypes A karyotype is a map of an individual’s chromosomes. Karyotypes are normally used if a chromosomal genetic disorder is suspected in an individual.
When Meiosis goes wrong…
Chromosomal Abnormalities You’ve seen the genes! Now you’ll see the chromosomes! Oh What Fun!
Karyotypes resulting in birth defects
Karyotypes & Genetic Disorders
Mistakes made during meiosis can lead to abnormal numbers of chromosomes. This occurs when a homologous pair of chromosomes fail to separate. These.
Autosomal and Sex chromosome abnormalities
Chromosomes & Human Heredity
Ch. 14 The Human Genome.
Chromosomal Mutations & their effects
Cell Division Meiosis Cell Division Meiosis Abnormal Meiosis.
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