Zusammenfassung der Ressource
Meiosis
- Prophase 1
- Chromatin condenses and supercoils
- Homologous pairs come together to form a bivalent
- The non-sister chromatids wrap around each other at the chiasmata
- Swap sections of
chromatids (crossing over)
- Nucleolus disappear and the nuclear envelope disintegrates
- Spindle forms, this is made of microtubules
- Metaphase 1
- Bivalents line up across the equator
- Spindle fibres attach to centromeres
- Bivalents are randomly assorted
- Anaphase 1
- The homologous chromosomes in each bivalent
are pulled by the spindle fibres to opposite poles
- Centromeres do NOT divide
- Chiasmata separate and lengths of the chromatid that have
been crossed over remain with the chromatid
- Telophase 1
- Two new nuclear envelopes form, one around each set of
chromosomes at each pole
- Cell divides by cytokinesis
- Chromosomes uncoil
- Prophase 2
- Nuclear envelope breaks down
- Nucleolus disappears
- Chromosomes condense
- Spindle fibres form
- Metaphase 2
- The chromosomes line up at the equator
of the spindle attaching by the
centromeres
- The chromatids are randomly assorted
- Anaphase 2
- The centromeres divide and the chromatids are
pulled to the opposite poles by the spindle fibres
- The chromatids randomly segregate
- Telophase 2
- Nuclear envelope reforms around the haploid daughter cells
- In animals the two cells now divide to give 4 haploid cells
- IPMAT- Interphase, Prophase, Metaphase, Anaphase and Telophase
- Prophase- Preparation
- Metaphase- meet in the Middle
- Anaphase- When the chromatids are pulled they give an A shape
- Telophase- Two new nuclear envelopes