Transcript Mitosis
REPAIRS BROKEN BONES, BURNS, CUTS, AND SCRAPES? CAUSES CANCER? TRANSFORMS US FROM 2 CELLS TO 20 BILLION? Allows organisms, including you, to GROW Replace old cells Increases the number of cells Every day billions of red blood cells in your body are destroyed and need to be replaced --- HOW? MITOSIS During the time it takes to read this sentence, 6 million new red blood cells were produced! Begins with organism’s formation or birth Growth and Development Death Individual cells follow the same life cycle Cell Cycle: series of events that takes place from one cell division to the next Not the same for all cells Examples ▪ Bean Plants 19hours ▪ Animal Embryos 20 min 1. 2. INTERPHASE MITOSIS 1. PROPHASE 2. METAPHASE 3. ANAPHASE 4. TELOPHASE Period of growth &development Before a cell can divide, a copy of its hereditary material must be made So each new cell can receive a copy Nucleus divides & cytoplasm separates Mitosis: nucleus divides to form two identical nuclei Steps 1. 2. 3. 4. Prophase Metaphse Anaphase Telophase A Chromosome is a structure that contains the cell’s hereditary material (DNA) Found inside the nucleus When cells are ready to divide, each duplicated chromosome condenses into thick strands called chromatids Chromatids: duplicated chromosomes formed during interphase that are thick and coiled together Needed for mitosis Centromere Chromatids are tightly coiled together Nucleolus and nuclear membrane disintegrate Spindle fibers begin to stretch across the cell The chromatid pairs line up along the equator (or middle) of the cell Pairs of chromosomes are separated Each half of the chromatid is pulled to an opposite side of the cell Spindles disappear Chromosomes uncoil New nucleus forms Mitosis ends Cytokinesis After mitosis Cytoplasm separates Cell membrane moves inward and pinches off = TWO separate cells Division of the nucleus Produces two new nuclei that are identical to each other and the original cell Each cell in your body has 46 chromosomes or 23 pairs Each new cell also has 46 chromosomes Sexual reproduction requires two organisms Asexual reproduction: a new organism is produced from one parent Produces offspring that are identical to parent Reproduce asexually Produce horizontal stems called runners that create new strawberries Bacteria CANNOT reproduce by mitosis They are prokaryotic – NO Nucleus Reproduce by fission Used by cells with no nucleus to copy genetic information and divide New organism grows from the body of the parent When the bud is large enough it breaks away to live on its own Some organisms can regrow damaged or lost body parts Sea Stars Cancer is the result of errors during mitosis Normally healthy cells being reproducing out of control and can grow into structures called tumors