meiosis Flashcards
What is meiosis?
Refers to the production of 4 non identical daughter cells (germline cells)
Outline the first step of meiosis I
Prophase I:
Chromosome condense and nucleus breaks down
- Homologous chromosomes pair up, aligning next to each other along their full length
Outline the second step of meiosis I
metaphase I: independent assortment
Homologous chromosomes line up along the equator
Outline the third step of meiosis I
Anaphase II: random segregation
Homologous pairs are separated, pulled to opposite ends of the elll
Sister chromatids remain attached
Outline the fourth step of meiosis I
Telophase:
Chromosomes arrives at opposite ends of cell
Two diploid cells are formed by cytokinesis
In meiosis II, there is no interphase stage. outline the first stage of meiosis II
Prophase II:
Chromosomes condense and the nucleus breaks down
Outline the first step of meiosis II
Metaphase II:
Chromosomes line up at the equator
Outline the second step of meiosis II
Anaphase II:
Sister chromatids are repeated by the spindles
Outline the third step of meiosis II
Telophase II:
Cytokinesis splits the cell into 2 new cells
Nucleus reforms
4 haploid daughter cells are formed that are not identical
Sources of genetic variation:
Where does crossing over occur?
Crossing over (prophase I)
Non sister chromatids crossover and exchange genetic material and paternal genes
Creates unique combinations of allele pairs on chromosomes
Recombination of maternal and paternal gene
Sources of genetic variation:
Where does Independent assortment occur?
Independent assortment (metaphase I)
Homologous pair of chromosomes line up along cell’s equator
Arrangement is random and independent of chromosomes
Genetic variation as daughter cells are different
Sources of genetic variation:
Where does random segregation occur?
Random segregation (anaphase I)
Chromosomes of homologous pairs move to independent poles as they are seperated, they are independent of each other.
