Meiosis Flashcards
What is an autosome?
any chromosome in an organism that is not a sex chromosome.
What is a sex chromosome?
chromosome responsible for determining the biological sex of an organism.
What is a germline cell?
Precursor diploid cells for gametes.
Define diploid
the number of chromosomes found as homologous pairs in a cell.
Define haploid
one of each pair of homologous chromosomes.
What is a homologous chromosome?
Chromosomes that have the same size and length, have the same centromere position and share the same genes at the same gene loci.
Where does meiosis occur?
Germline cells in the sex organs (gonads)
What is the purpose of meiosis?
Produce four haploid gametes to be used in fertilisation.
How many nuclear divisions are in meiosis?
2
How many times does DNA replication occur in meiosis?
1
What occurs during prophase I ?
Chromosomes are visible and condensed. Crossing over occurs.
What is crossing over?
Crossing over between homologous pairs of chromosomes is where alleles are exchanged. This creates new allele combinations on chromatids (called recombinant chromatids), which leads to the genetic variation.
What happens during Metaphase I ?
Homologous chromosomes align on the equator. Independent assortment occurs.
What is independent assortment?
Independent assortment of chromosomes is where the homologous chromosome pairs randomly align on the equator of the cell. This creates new chromosomal combinations.
What happens during Anaphase I ?
Homologous pairs are pulled to opposite poles of the cells by spindle fibres. Centromere doesn’t divide.
