4.3 - Sexual Passing of Traits (Meiosis)

Gametes

Haploid sex cells

Fertilization

The process where two gametes come together to form a zygote

Diploid (2n)

Genetic info from both sides

Haploid (n)

Genetic info from one side

Homologous pairs of chromosomes

Chromosomes that create a full set of genetic info

Sister chromatids

two identical chromosomes

Meiosis I

Homologous pairs separate, creating two haploid daughter cells, with half the genetic info

Prophase I

Homologous pairs come together to form a tetrad

Metaphase I

Tetrads line up in the middle of the cell

Anaphase I

Homologous pairs are separated

Telophase I

The two sides pinch off, creating two new haploid cells, each with two pairs of chromatids

Meiosis II

The two daughter cells separate into four, each with two chromatids

Prophase II

The two cells from meiosis I each have two replicated chromosomes

Metaphase II

The two replicated chromosomes line up in the middle of each cell

Anaphase II

The sister chromatids from each chromosome are pulled apart

Telophase II

The two sides of each cell pinch off, forming four haploid cells, each with two chromatids

Sexual reproduction

Requires two parents, results in genetic variation

Crossing over

The process where chromosomes swap parts, causes genetic variation

Recombinant chromosomes

Chromosomes that have unique combinations, results of crossing over

Independent assortment

Chromosomes line up randomly during metaphase, not affected by the movement of the others

Nondisjunction

When chromosomes fail to separate properly, causing daughter cells to have the wrong number of chromosomes

Genetic diversity

Helps organisms have adaptability