Chromosomes In Motion Sketch a chromosome and label its parts. One chromosome Two chromatids Two copies of DNA One chromosome One chromatid One copy of DNA

Chromosomes In Motion Sketch and label each phase of mitosis. Centrioles Chromatin Interphase Nuclear envelope Cytokinesis Nuclear envelope reforming Telophase Anaphase Individual chromosomes Metaphase Centriole Spindle Chromosomes (paired chromatids) Prophase Spindle forming

Mitosis Questions: 1. What are the main purposes of mitosis? Growth of organism, decrease cell volume, repair after injury, asexual reproduction 2. An organism has 20 types of chromosomes. How many chromosomes would be found in a body (somatic) cell? How many chromosomes would be found in a gamete? 40 chromosomes in somatic (body) cell (2N) 20 chromosomes in gametes (sperm and egg cells) (N)

Mitosis Questions: 3. Name a specific cell type in your body where you would expect mitosis to be occurring right now (an area with a high mitotic rate). Skin, intestines, cells in bone marrow that produce blood cells

Chromosomes In Motion Sketch and label each phase of meiosis. centrioles spindle chromosomes (DNA) Meiosis I

Meiosis II spindle centrioles chromosomes (DNA) Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells.

Meiosis Questions: a. What is the main purpose of meiosis? What type of cells are produced? Purpose - To produce 4 cells that are genetically different from each other and the original cell – ensures genetic variation in offspring. Type of cell - Gametes (sex cells) are produced b. Why do sexually reproducing organisms need to carry out meiosis? Meiosis has to occur in order for gametes to have a haploid number of chromosomes. Fertilization requires two haploid cells in order to make a diploid zygote.

(body) (sperm or egg)

What happens to the chromosomes during interphase prior to mitosis and meiosis beginning (specifically, the S phase)? Copied/Replicated/duplicated 2. What happens to the cell during cytokinesis? The cytoplasm is divided between the daughter cells as the cell membrane pinches in to form new daughter cells.