1. Karyotypes

2. a picture of someone’s chromosomes
Karyotypes
a picture of someone’s chromosomes
Centromere

3. Banding Pattern “Bands” are large segments of DNA
**Remember what chromosomes are made up of

4. Chromosome Pair #23 determines sex
Exception: Position 23
Chromosome Pair #23 determines sex

5. Female 23rd pair of chromosomes are homologous
Both chromosomes are “X” chromosomes X

6. Male 23rd pair of chromosomes are NOT homologous
One chromosome is “X” and the other is a “Y” chromosome

7. Disjunction
Normal separation of Chromosomes and Chromatids during Meiosis I and Meiosis II (Anaphase I & II)

8. Has 46 chromosomes for humans
Normal Karyotypes
Has 46 chromosomes for humans
Arranged in 23 pairs

9. Failure to separate homologous pairs
NON-disjunction
Nondisjunction during Meiosis I
Metaphase I
Anaphase I
Failure to separate homologous pairs

10. Failure to separate Chromatids
NON-disjunction
Nondisjunction during Meiosis II
Metaphase II
Failure to separate Chromatids
Anaphase II

11. What does nondisjunction cause?
Missing Chromosomes – Monomy
Embryo/Fetus will not survive
Means 45 chromosomes
Exception is this can occur on 23rd chromosome pair
Extra Chromosomes – Trisomy
Means 47 chromosomes
Down Syndrome (Trisomy 21)
Patau Syndrome (Trisomy 13)
Klinefelter’s Syndrome (XXY)
Turner’s Syndrome (X-)
XYY Syndrome
And many more………….

12. Trisomy 21 – Down Syndrome
Extra Chromosome 21

13. Trisomy 13 – Patau Syndrome
Extra Chromosome 13
Symptoms can include
Cleft lip or palate
Close-set eyes -- eyes may actually fuse together into one
Decreased muscle tone
Extra fingers or toes
Hernias
Hole, split, or cleft in the iris
Low-set ears
Mental retardation
Scalp defects (absent skin)
Seizures
Single palmar crease
Skeletal (limb) abnormalities
Small eyes
Small head
Small lower jaw
Undescended testicle

14. Klinefelter’s Syndrome (XXY)
Extra Sex Chromosome “X”

15. Turner’s Syndrome (X-)

16. Jamie Lee Curtis XY male with Androgen Insensitivity Syndrome (AIS)
resistant to androgens
the hormones responsible for male sexual development

17. QUESTIONS???