Reproduction of Cells Asexual Vs Sexual Reproduction

Asexual Reproduction Single parent passes complete copy of genetic information to its offspring – Identical to parent 4 types – Binary fission – Fragmentation – Budding – Parthenogenesis

Binary Fission DNA duplicates -> Cell grows -> Cell splits

Fragmentation Body breaks into several pieces and grow new parts or whole organism

Budding New individuals split off from existing ones

Parthenogensis Female makes viable egg that grows into an adult without being fertilized by male

Sexual Reproduction Genetic material given to offspring by two individuals – Offspring are genetically different from parents – Gametes Reproductive cell (sperm or egg) – Division of germ cell – Haploid cells created through meiosis Union produces zygote

Meiosis Cell reduces chromosome number in new cells to half the number of the original cell Sperm and egg (1n each, haploid) – Combine result in zygote (2n, diploid)

Meiosis Interphase Begins with duplicate set of chromosomes like mitosis Two divisions results in four (1n, haploid) cells – Meiosis I and Meiosis II

Meiosis I Prophase – Chromosomes condense – Spindle fibers form – Homologous chromosomes line up next to each other (synapsis) – Tetrads align side by side Twist around each other Portion breaks off to the adjacent chromatid – Crossing – over results in new mix of genetic information

Meiosis I Similar to mitosis – Metaphase I – Anaphase I Independent assortment – Telophase I Results in two cells with a chromosome from each pair of homologous chromosomes

Meiosis II Prophase II, no duplication of chromosomes Metaphase II Anaphase II – Chromatids separate Telophase II Cytokinesis II – 4 new genetically different haploid cells

Genetic Variation Crossing – over Independent assortment Random fertilization

Development of Gametes Testes in males – Spermatogenesis to create sperm Ovaries in females – Oogenesis to create ova – 1 egg and 3 polar bodies

Karyote