Agenda Go over Vocabulary set #2 Definitions Go over Section 8-2 Review Worksheet Notes: Meiosis Complete Meiosis Skill Worksheet Why is it important that meiosis produces haploid cells? What is a tetrad? What stage of meiosis can crossing over occur in? Why is crossing over important?

Binary fission- a form of asexual reproduction in prokaryotes Mitosis- process of cell division that forms two new nuclei each with the same number of chromosomes Asexual reproduction- reproduction that does not involve the union of gametes; offspring are genetically identical to parent Meiosis- process of cell division during which the number of chromosomes decreases to half the original number by two divisions of the nucleus Gamete- reproductive cell; sperm or egg Cell plate- the precursor of a new plant cell wall that forms during cell division Cytokinesis- division of cytoplasm Spindle fiber-one of the microtubules that assist in the movement of chromosomes in dividing eukaryotic cells Synapsis- pairing of homologous chromosomes during meiosis Tetrad- four chromatids in a pair of homologous chromosomes that come together as a result of synapsis Crossing-over- the exchange of genetic material between homologous chromosomes during meiosis that results in genetic diversity Genetic recombination- regrouping of genes in offspring that results in a genetic makeup different than parents Independent assortment- random distribution of the genes to gametes Spermatogenesis- the process by which male gametes form Oogenesis- the process by which female gametes form Polar body-a short lived product of the formation of gametes by meiosis Sexual reproduction- reproduction in which gametes fuse

Sexual reproduction requires meiosis. Meiosis produces haploid (n) gametes so that after fertilization, the embryos will be diploid. Meiosis also permits recombination (crossing over) so that each new gamete will have genes from both mother and father.

Homologous chromosomes synapse or pair. (tetrad) Crossing over occurs. Spindle fibers form. Prophase IMetaphase IAnaphase ITelophase I Microtubule spindle apparatus attaches to chromosomes. Homologous pairs align along spindle equator. Homologous pairs of chromosomes separate and move to opposite poles. One set of paired chromosomes arrives at each pole, and nuclear division begins.

Chromosomes recondense. Spindle fibers form between centrioles (if present). Prophase IIMetaphase IIAnaphase IITelophase II Microtubule spindle apparatus attaches to chromosomes. Chromosomes align along spindle. Sister chromatids separate and move to opposite poles. Chromatids arrive at each pole, and cell division begins. 4 haploid daughter cell. Genetically different due to independent assortment.

Crossing-over happens in early prophase I of meiosis.

Sister chromatids a b c d e f A B C D E F A B C D E F a b c d e f Homologous pair of chromosomes (schematized) Centromere

A B C D E F a b c d e f c d e f A B a b C D E F Chiasma

A B C D E F a b c d e f c d e f A B a b C D E F Why is recombination important?

Why is it important that meiosis produces haploid cells? What is a tetrad? What stage of meiosis can crossing over occur in? Why is crossing over important?

Agenda Vocabulary Review Game Notes Read Lecture Four: Sexual Evolution: From X to Y Web Activity Complete Essay Don’t forget Vocabulary Set #2 Quiz is Wednesday! How is spermatogenesis different than oogenesis? What is a polar body?

Spermatogenesis- Production of sperm cells Produces four haploid sperm cells

Oogenesis- Production of mature egg cells or ova Produces one haploid egg cell and 3 polar bodies which degenerate

Mitosis & Meiosis comparison Recombination happens here

Mitosis & Meiosis comparison II. (mitosis ends here)

Review How is spermatogenesis different than oogenesis? What is a polar body? Read Lecture Four: Sexual Evolution: From X to Y Web Activity:Log onto Howard Hughs Medical Institute Website and select “Gender Testing for Female Athletes” Complete Essay