Meosis Flashcards
What is meiosis?
A type of cell division that results in four individual daughter cells each with half the number of chromosomes in the production of gametes. It takes place in ovaries and testes.
What does it do to the diploid number?
It halves the diploid chromosome number, the haploid in gametes is 1n therefore in diploid cells it is 2n. They are formed in fertilisation and the chromosome number is maintained throughout the generations.
What does emissions do to variation?
It increases variation by crossing over between homologous chromosomes, so that alleles on the same chromosome are not always inherited together. Independent segregation of maternal and paternal chromosomes also occurs.
What does meiosis involve?
It involves 2 nuclear divisions. It has 3 stages interphase, meiosis I and meiosis II.
What occurs during meiosis interphase?
During interphase each chromosome replicates, each chromosome is made up of 2 chromatids.
What occurs during meiosis I?
Homologous chromosomes pair up and crossing over occurs. They then separate and the chromosome number of the daughter nuclei is halved, one nuclei to two nuclei.
What occurs during meiosis II?
Chromatids separate, two nuclei to four nuclei. It creates four daughter cells in total which are all genetically different.
What is independent segregation?
The order in which the homologous chromosomes separate.
Summing up of meiosis?
Creates 4 daughter cells, takes place in the ovaries for sexual reproduction. The haploid number is 1n. It produces genetically different cells and they line up in pairs along the equator. Crossing over occurs and the chromosome number changes.
