Cell Division

Importance of Cell Division Reproduce to make new organisms Allow multicellular organisms to Grow Replace the old worn-out cells Repairing damage

Asexual Reproduction Only 1 organism is needed!! Fission – Cell splits apart (bacteria) Budding – New organism grows on the body of its parent (hydra) Regeneration – Ability to re-grow lost or damaged parts (planarian)

Mitosis Nucleus divides (one time) to form 2 identical cells Type of asexual reproduction

Stages of Cell Cycle

Sexual Reproduction Involves the exchange of genetic information between 2 organisms This creates a brand new, genetically unique organism

During fertilization sex cells (egg & sperm) combine to produce a zygote that will develop into a new organism

Types of cells Diploid – cells with pairs of chromosomes (body cells) Haploid – have only one of each chromosome (sex cells)

Human diploid cells have 23 pairs of chromosomes (46 total chromosomes) Human haploid cells only have 23 chromosomes

Each haploid cell contains half the number of chromosomes as their parent cell 46  23

Meiosis One diploid cell divides and makes four haploid sex cells Involves two divisions of the nucleus and cytoplasm Meiosis I & Meiosis II

Meiosis I

Meiosis II

Meiosis Video: https://www.youtube.com/watch?v=MqaJqLL49a0&feature=related

Mitosis Meiosis 1 Division that produces 2 daughter cells 2 Divisions that produces 4 daughter cells Same # of chromosomes as the parent cell (diploid) Half the chromosomes of the parent cell (haploid) Genetically the same Genetically different combinations Help humans to grow and repair Used for sexual reproduction