REPRODUCTION STRATEGIES Genetics Unit November 9, 2015

Asexual Reproduction ■Definition: the production of genetically identical offspring from a single parent. ■Single-celled Organisms –Cell division is the only form of reproduction  binary fission. –Simple, efficient, and effective. –Populations increase in size very quickly. ■Think about it. Why do bacterial infections spread so quickly through school? Binary Fission in E.coli Interphase- including DNA Replication Mitosis- division of nucleus Cytokinesis Two identical E.coli cells

Budding ■Definition: type of asexual reproduction where a parent organism replicates to produce a clone that eventually splits off from the parent body. ■Example: Hydra –Small bud grows off of adult hydra. –Small bud will eventually break off and become independent organism. –Asexual reproduction in an animal. ■Example: Yeast Hydra bud- eventually bud will become an individual organism. outube.com/w atch?v=iOvrq6 ssy2Y Yeast bud- eventually bud will become an individual organism.

Fragmentation and Regeneration ■Definition: types of asexual reproduction that enable some invertebrates to reproduce new individuals or new body parts from incomplete fragments of the parent body. ■Example: Planaria –Section of planaria tissue removed from an adult. –Tissue fragment grows and differentiates into an adult through the process of mitosis. ■Example: Starfish can grow a new arm by mitosis to replace one lost by injury. Regeneration of starfish. Fragmentation of Planaria.

Sexual Reproduction ■Definition: involves the fusion of two separate parent cells. ■Offspring produced by sexual reproduction inherit some of their genetic information from each parent. –One gamete is donated from each parent. –When two gametes fuse, a zygote is formed. ■Offspring is genetically different from parents. Zygote Gamete from dad Gamete from mom

Think-Pair-Share Think-Pair-Share Compare and contrast the two reproductive strategies. Asexual ReproductionSexual Reproduction

Think-Pair-Share Asexual Reproduction Advantages Disadvantages

MEIOSIS OVERVIEW Genetics Unit November 9, 2015

Chromosome Number Diploid Cells ■Cell that contains two sets of chromosomes (one from mom, one from dad). ■Chromosomes are said to be homologous. ■Chromosomes have different genetic information. ■2N ■Example: Humans –23 different chromosomes. –Our cells have 46 chromosomes (23 from mom, 23 from dad). Haploid Cells ■Cell that contains only one set of chromosomes. ■N ■Example: Gametes –Male sperm cells. –Female egg cells.

Q: How are haploid gamete cells produced from diploid cells? A: Meiosis ■Definition: a process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cells. ■Two Divisions –Meiosis I –Meiosis II