Cell Division Meiosis Flashcards
What is another name for Meiosis?
Gametogenesis; Reduction Division
List every step in Meiosis.
Interphase, Meiosis 1: Prophase 1, Metaphase 1, Anaphase 1, Telephase 1, Meiosis 2: Prophase 2, Metaphase 2, Anaphase 2, Telephase 2 + Cytokinesis
What is the final result of Meiosis
4 Gamates
Describe Interphase for Meiosis
Like mitosis, the cell grows and continues to function normally and produces lots of enzymes necessary for DNA replication. Chromosomes are replicated into identical sister chromatid dyads connected by a centromere as the MTOCs replicate, the centrioles are doubled, and the mitochondria and or the chloroplasts divide; there is a massive production of tubulin and chromosomes coil more
Describe the first step in Meiosis 1
Prophase 1: Chromosomes become fully condensed; Centrioles move to opposite ends of the cell, where they produce polar microtubules that produce aster fibers to connect the centrioles to the cell membrane; Nuclear envelope dissolves, Kinetochore Microtubules are produced by MTOCs; + Homologous Chromosomes hydrogen bond to one another
What are homologous chromosomes?
Two chromosomes of the same type with different versions of genes or different alleles
What is synapsis?
The pairing of homologs
What is it called when homologs pair in prophase 1?
Synapsis
What structure is formed due to the hydrogen bonds of homologous chromosomes in prophase 1?
Tetrads (Bivalence)
How many tetrads in Prophase 1?
23
What happens as a result of Meiosis?
A reduction in Ploidy
What is this called when homologous chromosomes exchange segments?
Crossing over
What happens when Homologous chromosomes cross over?
They exchange segments 50-70 times.
What happens in the second phase of Meiosis 1?
Metaphase 1: Kinetochore microtubules arrange with Tetrads that line up at the metaphasic plate
Describe Independent assortment
The random orientation of homologs (Homologous chromosomes) at the metaphasic plate. The parental sets of chromosomes do not stay together during Meiosis 1.
What is it called when homologs randomly orient at the metaphase plate?
Independent assortment
What happens in the third phase of Meiosis 1?
Anaphase 1: The homologs will separate, and dyads will get pulled to opposite ends of the cell.
What happens at the end of Meiosis 1?
Telephase 1: Dyads reach the ends of the cell, the spindle apparatus dissolves, and a belt of actin along the metaphasic plate pinches the cell in half. The nuclear envelope does not reform, and chromosomes are not decondensed.
What happens in Meiosis 2?
Everything happens the same as mitosis.
Describe the steps of Meiosis 2.
First, the chromosomes condense, and centrioles move to opposite ends of the cell, producing polar microtubules that produce aster fibers that connect centrioles to the cell membrane. Then, the nuclear envelope dissolves, and MTOCs produce Kinetochore microtubules. Next, K Microtubules arrange with dyads at the center of the cell. After centromeres break, chromatids are pulled to opposite ends of the cell while polar microtubules lengthen. Finally, chromatids reach the ends of cells, where the nuclear envelope is reformed, and the spindle apparatus dissolves. Chromosomes decondense, and an actin belt pinches the cell along the metaphasic plate.
What is the difference between spermatogenesis and Oogenesis
Oogenesis results in polar bodies.
What is the significance of the egg cell being immense?
It is a bigger target for the sperm. Stores all the energy needed for the 5 days the cell can not draw energy from external sources. It needs to support life.
What is an error in Meiosis?
Non-disjunction
What is Non-disjunction?
Some or all the homologous chromosomes fail to separate during meiosis 1 resulting in 2 outcomes
