Lec 17.5: Meiosis/Mutations

Meiosis Variation

64 trillion different combinations with fertilization

• lots of genetic variability

• some variability is beneficial while some is not

Trisomy 21/ Down Syndrome

a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome

• SHOWN: physical growth delays, specific facial feature, intellectual disabilities

• CAUSE: heart defects, epilepsy, leukemia, thyroid disease, mental disorders

• risk increases as you reach 45+

• TREAT: prenatal screening, diagnostic/genetic testing

Trisomy 18/ Edwards Syndrome

a chromosomal disorder caused by the presence of all, or part of an extra 18th chromosome

Trisomy 13/ Patau Syndrome

a chromosomal disorder caused by the presence of all/part of an extra 13th chromosome

• CAUSE: intellectual disability, motor disorders, microcephaly, holoprosencephaly, kidney/heart defects

• Infants die within first few days/weeks because of severe neurological problems/heart defects

Klinefelter Syndrom/ XXXY

males with extra X chromosome

• CAUSE: sterile, deep muscles, taller, poor coordination, less body hair, smaller genitals, breast growth, less interest in sex

• finds out after puberty

• no cure: speech or physical therapy, testosterone replacement

• usually randomly occurance

Turner Syndrom/ XO

partly or completely missing an X chromosome

• CAUSE: short and webbed neck, low set ears, hairline, short sature

• sterile (no periods/ breast development)