2.6.2 Meiosis Flashcards
What is Meiosis?
Production of four Haploid Gametes creating Genetic Variation
What is Genetic Variation?
Naturally occurring genetic differences among individuals of the same species
What Two ways does Genetic Variation occur during Meiosis?
Crossing over of chromatids - Prophase I
Independent assortment of chromosomes - Metaphase I
What are Homologous Chromosomes?
Genetically similar Chromosomes
What are Bivalent Chromosomes?
A pair of homologous Chromosomes (Four chromatids)
What occurs in Prophase I of Meiosis?
Nuclear envelope breaksdown
Chromosomes coil up
Spindle FIbres form and poles
Homologous Chromosomes “pair up” (become bivalent)
What is Crossing over and when does it occur?
The exchange of DNA between paired homologous chromosomes in Prophase I
What is a Chiasma ( The Chiasmata )
The region where two homologous chromosomes make contact in a bivalet
What occurs in Metaphase I of Meiosis?
Spindle fibres move Bivalents to equator
Independant assortment occurs
What occurs in Anaphase I of Meiosis?
Seperation of Homologous Chromosomes
NO seperation of Centromere
What occurs in Telophase I of Meiosis?
Nuclear envelope reforms
Chromosomes uncoil
Meiosis II is similar to what process?
Mitosis
What occurs in Prophase II of Meiosis II?
Nuclear envelope breaks down
Chromosomes coil up
Spindle FIbres form at poles
What occurs in Metaphase II of Meiosis II?
Spindle FIbres move Chromosomes to equator attatched at the Centromere
(Independent assortment of sister chromatids can occur)
What occurs in Anphase II of Meiosis II?
Centromere splits and Spindle fibres pull one sister chromatid to each pole
What is the main difference between Anaphase I and Anaphase II of Meiosis?
Anaphase I - Chromosomes are pulled, Centromere does not split
Anaphase II - Chromatids are pulled, Centromere does split
What occurs in Telophase II of Meiosis II?
Nuclear envelope reforms
Chromosomes uncoil
