AIM: How does meiosis and fertilization increase variation among offspring? Como afecta la meiosis y la fecundacion la variacion en la decendencia?

What do these pictures show?

Genetic Variation/ Variacion Genetica Variation between organisms due to: Meiosis and Fertilization Variacion entre los organismos como resultado de la meiosis y fertilizacion

Meiosis : DNA replicates crossing over 1 st Division – 2 cells 2 nd Division – 4 haploid cells

Crossing Over During meiosis homologous pairs line up and exchange pieces (switch some genes) Durante la meiosis pares homólogos se alinean e intercambian de piezas (interruptor de algunos genes)

Genetic Recombination Recombinacion Genetica Switching pieces of chromosomes results in new combinations of genes on the chromosomes. Cambio de piezas de las cromosomas resulta en nuevas combinaciones de genes.

One of each of the chromosomes goes into each of the 4 gametes that form during meiosis. Una cromatida de cada cromosoma esta presente en cada gameto (4) formado durante el proceso de meiosis.

What is the result of independent assortment? Different combinations of genes in each new gamete. Como resultado de esta reorganizacion de genes, se crea una combinacion diferente en cada gameto nuevo.

Fertilization/ Fecundacion Every egg formed by the mother is different. Every single sperm formed by the father is different. Every single zygote is different. Cada ovulo formado por la madre es diferente. Cada espermatozoide formado por el padre es diferente. Cada cigoto es diferente.

Trillions of possible combinations Trillones de combinaciones posibles Variation/ Variacion

Variation What type of cell division leads to variation? How? How does fertilization lead to genetic variation?