Meiosis Flashcards
Meiosis
Name every stage in Meiosis:
6.1
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Cytokinesis 1
Prophase 2
Metaphase 2
Anaphase 2
Cytokinesis 2
Why do we go through PMAT twice in Meiosis?
Because for Sperm and Egg Cells, we want them to come together to form a cell with 46 “full” Chromosomes (meaning with 92 Chromatids).
We don’t want a cell having more than 46 “full” Chromosomes.
What is the common confusing thing with counting Chromosomes during Meiosis and Mitosis?
Why is it confusing?
6.1
Chromosomes are measured by their Centromeres (middle attacher of sister chromatids).
It is confusing because a cell can have Chromosomes with 2 sister chromatids, but then when the cell splits, there could still be the same amount of chromosomes-its just that the number chromatids have been cut in half.
You can think of Chromosomes with 2 sister chromatids as “full” chromosomes, whereas Chromosomes with 1 sister chromatid are half-full.
Before Meiosis 1, how many Chromosomes and Chromatids does the cell start with?
Mention every stage in Meiosis 1 and 2 where the Chromosome or Chromatid number changes.
What is the end result of Meiosis?
6.1
Cell starts with 46 Chromosomes, and 92 Chromatids (46 “full” Chromosomes).
In Meiosis 1, after the cell splits after during Cytokinesis 1, there are 23 Chromosomes and 46 Chromatids (23 “full” Chromosomes).
In Meiosis 2, after the cell splits during Cytokinesis 2, there are 23 Chromosomes and 23 Chromatids (“half-full” Chromosomes). This is the end value.
For Meiosis 1 and 2, at what stages are cells diploid?
6.1
Prophase 1
Metaphase 1
Anaphase 1
For Meiosis 1 and 2, at what stages are cells haploid?
6.1
Cells are first haploid after the cells split in Telophase 1.
Cells are then Haploid for the rest of Meiosis from there on out.
What 3 things happens in Prophase 1 of Meiosis 1?
6.1
- Chromosomes condense and thicken.
- Each Chromosome finds their Homologous Pair to form a tetrad.
- Crossing over happens
Name of Homologous Pairs during Prophase 1
6.1
Tetrad
What is Crossing Over, in Meiosis.
6.1
(During Prophase 1)
It is when the Chromosomes lined up in Homologous pairs (tetrads) exchange some genetic info between each other. The Chromosomes switch some of their DNA with the other chromosome.
Define Chiasma, in the context of Meiosis.
6.1
It is the point on each Chromosome, where Crossing Over happens (in Prophase 1).
What phrase is used to describe Chromosomes after Crossing Over happens?
6.1
Recombinant Chromosomes
What is the significance of Crossing Over in Meiosis?
6.1
This contributes to the genetic diversity of humans, which increases the change of our species’ continuous survival (tied into Evolution).
What happens in Metaphase 1?
6.1
Chromosomes line up in PAIRS in the center of the cell (not single file line).
How does Metaphase 1 help in terms of genetic diversity and variety?
6.1
Helps due to independent assortment.
What is independent assortment?
6.1
It is how the Chromosomes randomly line up in the middle of the cell (during Metaphase 1).
