Lesson 20: Meiosis Flashcards
What is synapsis?
The homologous chromosomes come together
What is a tetrad?
The synapse pairs (one chromosome inherited from the mother and one from the father)
What is a chiasma?
An X-shaped structure.
–The point at which the homologous chromosomes overlap, where chromosomes exchange segments resulting in genetic variability in daughter cells
What happens during Prophase 1?
Synapsis and chromosome segment exchange
What happens during Metaphase 1?
Chromosome pairs line up along the centerline of the cell DOUBLE-FILE (because the chromosome pairs are still synapsed)
What happens during Anaphase 1?
Synapsed chromosomes separate. Chromosome pairs move to opposite ends of the cell (homologous chromosomes are separated as opposed to the separation of sister chromatids in Mitosis)
What happens during Telophase 1?
Chromosomes reach the poles of the cell
How do you count the number of chromosomes in a cell?
By counting the number of centromeres present in the cell
What happens during Prophase 2?
Duplicated chromosomes begin to move to the middle of the cell
What happens during Metaphase 2?
The chromosomes line up along the center line of the cell
What happens during Anaphase 2?
The sister chromatids move to opposite ends of the cell becoming independent chromosomes
What happens during Telophase 2?
The chromosomes reach the poles of the cell
What type of division is Meiosis 1 known as?
A reduction division because it results in a reduction in the number of chromosomes
What is the major difference between Mitosis and Meiosis 2?
In Meiosis 2 the cell only has 1 complete set of chromosomes (is haploid), whereas in Mitosis there are two complete sets of chromosomes (diploid)
Is Meiosis 2 considered a reduction division?
NO, only in Meiosis 1 are the number of chromosomes divided in half