1. Mutations & Their Implications

2. Human Chromosomes
There are 46 chromosomes (23 homologous pairs) in each somatic cell
22 pairs of autosomes
1 pair of sex chromosomes
XX = Female, XY = Male
Karyotype - chromosomes are arranged according to shape and size

3. Types of Mutations
A mutation is any change to the DNA of a cell

4. Nondisjunction and Chromosomal Disorders
Nondisjunction – failure of chromosomes to separate and segregate into daughter cells
Nondisjunction may occur during meiosis 1 or meiosis 2
Abnormal number of chromosomes may result

5. MEIOSIS I MEIOSIS II Nondisjunction during meiosis I Non-disjunction
Replicate DNA
Non-disjunction
MEIOSIS II
Disomic gametes
Nullisomic gametes

6. MEIOSIS I MEIOSIS II Nondisjunction during meiosis II Non-disjunction
Replicate DNA
MEIOSIS II
Non-disjunction
Disomic
Nullisomic
Monosomic
Monosomic
gametes

7. EXAMPLES OF NON-DISJUNCTION

8. Down Syndrome, 47, 21+ This condition is called trisomy 21.
Person with this condition suffers from
the Down syndrome.
Characteristic facial features:
Round face
Flattened nose bridge
Small, irregular teeth
Short stature
Heart defects

9. Klinefelter's Syndrome, 47, XXY
It is the most common sex chromosome disorder
Symptoms:
Language impairment
Lanky, youthful build or rounded body type
Low levels of Testosterone and small testicles / Infertile

10. Turner’s Syndrome, 45, XO Common symptoms: Short stature
swelling of the hands and feet
Broad chest and widely spaced nipples
Low hairline
Low-set ears
Reproductive sterility
Increased weight, obesity
Small fingernails
Characteristic facial features
Webbed neck

11. Edward’s Syndrome, 47, 18+ Trisomy 18 Nondisjunction Symptoms
Small head
Mentally retarded
Internal organ abnormalities
90% die before 5 months of age

12. Jacob’s Syndrome, 47, XYY Normal physically Normal mentally
Increase in testosterone
Normal lifespan
1 in 4,400 birth
They may have never known…

13. Triple X Syndrome, 47, XXX Trisomy 23 nondisjunction
Normally physically Normal mentally
Fertile
1 in 2,500 births

14. Wolf-Hirschhorn Syndrome, 4p
Very rare
Affected children are small, with microcephaly and abnormal faces. There are cardiac, renal, and genital abnormalities. Most are stillborn or die in infancy.

15. Patau Syndrome, 47, 13+ Trisomy 13 nondisjunction Symptoms Small head
Small or missing eyes
Heart defects
Extra fingers
Abnormal genitalia
Mentally retarded
Cleft palate
Most die a few weeks after birth