meowosis

What are the key events of Meiosis I?

• Tetrad formation

• Crossing Over

• Separation of the duplicated homologous chromosomes

What are the key events of Meiosis II?

• Random alignment of homologous chromosomes

• Random assortment of chromosomes into nuclei

When does tetrad formation occur?

Prophase I

When does crossing over occur?

Prophase I

When does separation of the duplicated homologous chromosomes occur?

Anaphase I

Which meiosis is the primary source of genetic diversity in gametes?

Meiosis I

What are tetrads and when are they built?

Tetrads are a pair of homologous chromosomes (4 sister chromatids)

They are built in Prophase I

What anchors homologous chromosomes in a tetrad?

Proteins

What occurs in Prophase I?

• Tetrads are built

• Crossing over occurs, resulting in a combination of chromosomes from paternal and maternal idk

What is crossing over?

Homologous chromosomes connect to one another and swap genetic information

What occurs in Prometaphase I?

The nuclear envelope around the tetrads breaks down and spindle fibers attach to and pull on the tetrads

What happens in Metaphase I?

The tetrads have been pulled to the metaphase plate in the middle of the cell

Maternal and paternal chromosomes in each tetrad line up randomly

What occurs in Anaphase I?

Proteins holding the tetrads together break and the homologous chromosomes in each tetrad are pulled to the opposite ends of the dividing cell

What occurs in telophase I?

The homologous chromosomes reach the opposite ends of the dividing cell, the plasma membrane pinches in, dividing the cell into two cells

Each new cell has one copy of the chromosomes, making haploid cells

What occurs in Prophase II and Prometaphase II?

A new set of spindle fibers develops to divide the genetic information, the fibers attach to and pull on each individual chromosome

What occurs in Metaphase II?

All chromosomes in both cells are randomly aligned along the metaphase plate

What occurs in Anaphase II?

The sister chromatids of each chromosome are separated from one another and pulled towards the opposite ends of the dividing cells

What occurs during Telophase II and Cytokinesis

New nuclear envelopes form around each set of chromosomes. Four haploid gametes are created

What is nondisjunction?

The failure of paired chromosomes to move to opposite sides of the spindle. If it occurs, the embryo inherits an extra chromosome. 

Which phases of meiosis increases the genetic diversity of gametes?

Prophase I, Metaphase I, Metaphase II

What is the difference between Random Assortment and Random Alignment?

Random Assortment is how homologous chromosomes separate randomly, and random alignment is the physical random positioning.

When does Random Alignment in Meiosis I occur and what is it?

Random Alignment occurs during Metaphase I and is the physical random positioning of homologous pairs at the metaphase plate, which leads to random separation in Anaphase I. Tetrads line up randomly.

When does Random Alignment in Meiosis II occur and what is it?

Random assortment is the random alignment of all single chromosomes in both cells along the metaphase plate, resulting in sister chromatids being pulled apart in anaphase II. 

What is Independent Assortment and when does it occur?

It is the random division of genetic information into gametes. It occurs during Metaphase I when tetrads line up randomly. It also occurs in Metaphase II when individual chromosomes lline up randomly.

What is crossing over?

The exchange of genetic information between non-sister chromatids in a tetrad. It generates recombinant chromosomes.