Sexual reproduction

Two cells combine- produce offspring

Cells called gametes (sex cells egg and sperms)

Meiosis steps in producing gametes (sex cells)

Occurs in female during fetal stage and stops-then completed during puberty

Gametes half the number of chromosomes as body cells (somatic cells -these are the ones you’ve been learning about up until now)

Cell divisions is undergone two times (meiosis 1 and meiosis 2)

Meiosis 1 homologous chromosomes separate

Meiosis 2, sister chromatid separate

Gene shuffling also occur in meiosis (good for gene variation or genetic diversity)

Only occurs in sexual reproduction

Sexual reproduction-two parents where asexual reproduction-only requires from one parent

Offspring are different genetically from each other, their parents, and the other of the same species

Body cells or somatic cells have a diploid number of cells (2n)

 two sets of chromosomes

Half  from parent 1 (23) egg and half from parent 2 (23) sperm cells

Sex cells or gametes have a haploid number (1n) of chromosomes

Fertilization, egg (1n) penetrated by sperm (1n) forming a zygote (2n)

Zygote undergoes meiosis and cell division to form an embryo.

If gametes didn’t have half number of chromosomes, offspring would have double the number of chromosomes each generation.

Crossing over between two homologous chromosomes during prophase 1, Non sister chromatic from different chromosomes cross over and exchange/switch segments of DNA. Crossing over produces gene variations.

Interkinesis is another name for interphase 2. There is no DNA replication during this phase. It’s a period of rest for cells in some species.