PBS 2.2.5

Goals:

  • Evaluate chromosome number and structure on a Karyotype

  • Model how the process of meiosis can lead to differences in chromosome number

  • Explain how chromosomal differences impact stature and function in the human body

Mitosis

  • Interphase - DNA replicates

  • Prophase - Chromosomes condense and mitotic spindle forms, nuclear envelope disappears

  • Metaphase - Chromosomes line up in the center, fibers pull on sister chromatids

  • Anaphase - Chromatids pulled to a side of the cell

  • Telophase and Cytokinesis - Cell splits in 2 - daughter cells identical

Meiosis

  • Interphase - DNA replicates

  • Prophase I - Homologous chromosomes pair up together

  • Metaphase I - Chromosomes line up at center, fibers attach and pull

  • Anaphase I - Homologous chromosomes separated

  • Telophase I & Cytokinesis I - Daughter cells look identical but genetically different

  • Prophase II - Chromosomes pair up with matching chromosome

  • Metaphase II - Chromosomes line up in the center, fibers attach at each end

  • Anaphase II - Sister chromatids pulled to opposite sides

  • Telophase II & Cytokinesis II - Daughter cells have half of original chromosomes, nucleus forms

Errors in meiosis can damage/alter number of chromosomes

Nondisjunction - members of a pair of chromosomes fail to separate

  • Monosomy - one fewer chromosome

  • Trisomy - one extra

  • Centromere - where sister chromatids are held together

  • Deletion - a segment of a chromosome

  • Duplication - segment is replicated and inserted next to original copy

  • Inversion - chromosome segment placed in wrong orientation

  • Insertion - part of one chromosome removed and added to another

  • Translocation - 2 chromosomes swap segments

Samples of karyotyping from blood and large tissues

Therapist - professionals who help patients mentally or physically in their quality of life