Meiosis Flashcards
What is meiosis ?
The process where 1 parent cell divides to produce 4 daughter cells.
The daughter cells have half the number of chromosomes of the parent cell.
This type of division takes place in the gonads (ovaries and testicles) to produce ova (eggs) or sperm.
What happens during the 2 stages of meiosis ?
Meiosis 1 = separation of homologous chromosomes
Meiosis 2 = separation of sister chromatins
Order of meiosis 1
Interphase
Prophase
Metaphase
Anaphase
Telophase
(It pays more at tescos)
Order of meiosis 2
Prophase
Metaphase
Anaphase
Telophase
Interphase
(Pays more at Tescos)
Meiosis 1
Interphase
Identical replication of DNA to create chromatin sisters.
Meiosis 1
Prophase
Nucleolus disappears
Centrioles migrate
Chromosomes condense
HOWEVER
Homologous chromosomes associate (they pair up)
-the homologous chromosomes (bivalent) become intimately entangled
-as they pull apart some points remain in contact
-genetic exchange occurs at chiasmata.
-creates a new unique genetic sequence
Meiosis 1
Metaphase
Bivalent orientates itself as a unit on the equator
Chromosomes weigh more than centrioles and so pull them apart.
Meiosis 1
Anaphase
Bivalent pulled apart. 1 chromosome (pair of chromatids) going to each pole.
Meiosis
Telophase 1
Chromosomes reach poles
Cytokinesis (cell splits)
Meiosis 2
prophase
Centrioles migrate to new poles (90 ° to original).
New spindle formation
Meiosis 2
Metaphase
Chromosomes move to equator
Chromatins orientate towards poles
Meiosis 2
Anaphase
Spindles attach
Chromatids separate
Meiosis 2
Telophase
Chromatids reach poles
Cytokinesis
Nucleolus reappears
Spindles disappear
Chromatids uncoil
