AP Biology Meiosis Part 1

Interphase

(before chromosome replication) . MITOSIS MEIOSIS Parent cell (before chromosome replication) Chiasma (site of crossing over) MEIOSIS I Propase Prophase I Chromosome replication Chromosome replication Tetrad formed by synapsis of homologous chromosomes Duplicated chromosome (two sister chromatids) 2n = 6 Chromosomes positioned at the metaphase plate Tetrads positioned at the metaphase plate Metaphase Metaphase I Anaphase Sister chromatids separate during anaphase Homologues separate during anaphase I; sister chromatids remain together Anaphase I Telophase Telophase I Haploid n = 3 Daughter cells of meiosis I 2n 2n MEIOSIS II Daughter cells of mitosis n n n n Daughter cells of meiosis II Sister chromatids separate during anaphase II

Parent to offspring

Mom and Dad’s DNA contribution The egg surrounded by sperm.

Locus (Gene locations on chromosomes)

Asexual reproduction (One parent) See the bud on the side… that is the “new” organism to be.

Sexual Reproduction (Two parents)

Lifecycles of organisms Key Haploid Diploid Haploid multicellular organism (gametophyte) Haploid multicellular organism Gametes n n Mitosis n Mitosis Mitosis n Mitosis n n n n n n Spores n MEIOSIS FERTILIZATION n Gametes Gametes n MEIOSIS FERTILIZATION MEIOSIS FERTILIZATION Zygote 2n 2n 2n 2n Diploid multicellular organism (sporophyte) Zygote 2n Diploid multicellular organism Mitosis Mitosis Zygote Animals Plants and some algae Most fungi and some protists

Female (XX) Karyotype (Remember… “kary” means “nucleus”)

Male (XY) Karyotype

Germ cells at fertilization