Reproduction C-11-1

There are many types of reproduction

Reproduction C-11-1 Binary fission Done by bacteria

Reproduction C-11-1 Asexual Just split in half  Amoebas

Reproduction C-11-1 Fragmentation Pieces split off and each piece becomes a new organism  Starfish

Reproduction C-11-1 Budding Whole organism grows off another and then splits off  Hydra

Reproduction C-11-1 Parthenogenesis Female makes viable egg that grows without being fertilized  Water fleas

Reproduction C-11-1 Sexual 2 parents give genetic material to make offspring that are genetically different from them  Most eukaryotes * Advantage – genetic diversity

Reproduction C-11-1 Germ cells give rise to gametes = sex cells When gametes from the parents combine, the result is called a zygote

Reproduction C-11-1 Gametes = haploid 1 of each type of chromosome (1n) Zygote = diploid 2 of each type of chromosome (2n)

Reproduction C-11-1 For humans In each gamete, the 1n = 23 In each diploid cell the 2n = 46

Reproduction C-11-1 Homologous chromosomes Chromosomes of the same type Ex: chrom. 1 from mom is homologous to chrom. 1 from dad

Reproduction C-11-1 Autosomes Chromosomes that are not sex chromosomes

Meiosis C-11-2 Meiosis is cell division that makes daughter cells with half the number of chromosomes than the parent cell

Meiosis C divisions take place: Meiosis I - 1 st division Prophase I  Chromosomes condense  Nuclear envelope breaks down  Homologous chromosomes pair up  Crossing over can occur

Meiosis C-11-2 Metaphase I Spindle fibers move homologous chromosomes to middle of cell Homologous remain together

Meiosis C-11-2 Anaphase I Homologous chromosomes move to opposite poles

Meiosis C-11-2 Telophase I Chromosomes gather at the poles Cytoplasm starts to divide

Meiosis C-11-2 Cytokinesis Cytoplasm divides

Meiosis C-11-2 Now we have 2 cells with ½ the number of chromosomes... But we still have 2 chromatids on each chromosome We need to split these again

Meiosis C-11-2 Meiosis II Prophase II  New spindles form

Meiosis C-11-2 Metaphase II Chromosomes line up in the middle of cell

Meiosis C-11-2 Anaphase II Chromosomes divide at centromeres and chromosomes move to either pole

Meiosis C-11-2 Telophase II Nuclear envelope forms around each set of chromosomes Spindles disappear Cell begins to divide

Meiosis C-11-2 Cytokinesis Cell divides

Meiosis C-11-2 This results in a total of 4 new haploid cells that are genetically different from the parent cell.

Meiosis C-11-2 When this process occurs, the homologous chromosomes will be randomly distributed Called independent assortment

Meiosis C-11-2 Also, the fertilization of gametes is random as well. There are about 64 trillion combinations of chromosomes

Multicellular Life Cycles C-11-3 Diploid life cycles: Most animals have this Most of life is spent in this state All cells except gametes are diploid  To make gametes, meiosis must occur...slightly different in males and females:

Multicellular Life Cycles C-11-3 Spermatogenesis: Oogenesis:

Multicellular Life Cycles C-11-3 Haploid life cycle: Happens in most fungi and some protist Most of life spent in haploid state Only diploid structure is the zygote New haploid cells go through mitosis to make multicellular haploid individuals

Multicellular Life Cycles C-11-3 p 258

Multicellular Life Cycles C-11-3 Alternation of generations: Some organisms alternate between diploid and haploid phases Ex: PLANTS  The multicellular diploid phase = sporophyte  Produces spores through meiosis  Spore forms a multicellular gametophyte which is haploid  Gametophyte makes gametes which when fertilized give rise to sporophyte

Multicellular Life Cycles C-11-3