Meiosis Gamete Formation

Homework Complete Graphing handout And 11-4 in Guided Reading Workbook

Reproduction Asexual reproduction - Asexual reproduction is the formation of new individuals from the cell(s) of a single parent. The new cell (daughter cell) is usually identical to the parent. Sexual reproduction - In sexual reproduction, two individuals produce offspring that have genetic characteristics from both parents. Sexual reproduction introduces new gene combinations in a population

Diploid - term used to refer to a cell that contains both sets of homologous chromosomes Haploid - term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes

Chromosomes Human’s have 46 chromosomes 23 from your mother’s egg 23 from your father’s sperm A normal human cell is a diploid cell (2N) A sex cell or gamete (egg or sperm) is a haploid cell (N) In human cell’s what does N represent? 23

Apply what we learned about human cells to drosophila melanogaster. Does 2N or N represent this cell best? Is this cell haploid or diploid? What number does N represent?

Homologous - term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent Homologous chromosomes are similar in shape, position and information, but not identical to each other.

Meiosis Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Tetrad - structure containing 4 chromatids that forms during meiosis. crossing-over - process in which homologous chromosomes exchange portions of their chromatids during meiosis

Formation of a tetrad while going through the process of crossing-over This occurs during prophase I of meiosis

Meiosis is broken down into two halves. Meiosis I an Meiosis II

Meiosis II

Gamete Formation Meiosis produces four genetically different haploid cells.

Comparing Mitosis and Meiosis Similar processes with very different and distinct outcomes Mitosis results in the production of two genetically identical diploid cells (2N), whereas meiosis produces four genetically different haploid cells (N).