17.5 Meiosis and Mutations

Somatic Cell

Body cell (undergo mitosis)

Gametes

Reproductive Cells (sperm egg)

MEIOSIS

Haploid

Interphase (meiosis)

• Phase which comes before meiosis

  • Chromosomes duplicate/cell grow

Prophase I (Step one of Meiosis)

•  Chromos coil and become compact

• NONsister chromatids swap genetic material

Metaphase I: 2nd part of meiosis

Tetrads align at cell equator

• Anaphase I: 3rd part of meiosis

• Homologous pairs separate

• Sister chromatids still attached

Telophase I & Cytokinesis: 4th part of meiosis

• Duplicated chromosome reach poles

• Each nucleus has N

Prophase II: 1st part of Meiosis II

Chromos coil and become compact if uncoiled after M1

Trisomy 21/DOWN SYNDROME

• A choromosomal disorder caused by the presence of all, or part of an extra 21st chromosome

  • Physical growth delays, specific facial features, intellectual disabilities

  • Prone to: congenital heart defect, epilepsy, leukemia, thyroid diseases, and mental disorders

  • Risk of giving birth to a baby with it increase as eggs age (45+)

  • Treat: Prenatal screening or diagnostic testing or genetic testing

Trisomy 18/Edwards Syndrome

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

• Born small, with heart defects, microcephaly, intestines outside the body, and severe intellectual disability

  • Most die before birth; 7.5% chance of survival after 1 year

• Most are XX (female at birth)

• Rate if disease inc with eggs age