Cell Division Mitosis the process by which cells

Cell Division Mitosis: the process by which cells reproduce themselves, resulting in daughter cells that contain the same amount of genetic material as the parent cell. Simply put…how one cell becomes two

Cell Division Occurs in a series of stages of phases • Cell Division refers to the ENTIRE process • Mitosis is a phase of the cell cycle • Mitosis, itself, has four phases (Prophase, Metaphase, Anaphase, Telophase)

Animated Mitosis Cycle http: //www. cellsalive. com/mitosis. htm • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis

Life cycles of different cells: Our bodies are made up of tiny cells. They can only be seen with a microscope. Like people, cells grow and die. We make new cells through MITOSIS Cell Type Life Cycle (how often they go through Mitosis) Intestine lining Every 2 -3 days Stomach lining Every 5 days Skin cells Every 28 days Liver cells Every 42 days Bone cells Every 90 days Red blood cells Every 120 days

DID YOU KNOW? ? ? OUR BODIES MAKE 1, 000, 000 (ONE BILLION) CELLS EVERY DAY? ? OUR CELLS ARE CONSTANTLY DIVIDING. MITOSIS IS HOW WE MAKE NEW CELLS, AND GET RID OF OLD, DEAD CELLS.

New Body Cells The Cell Cycle (aka Cell Division and Mitosis) is how we make new body cells. Our body cells are called “somatic” (SO-mat-TICK) All cells in our body (somatic cells) reproduce through MITOSIS, except our GAMETES (or sex cells)— meaning sperm or eggs. Sperm and eggs reproduce through MEIOSIS

interphase Has 3 phases G 1 (growth) S (DNA synthesis, DNA replication) G 2 (growth) A cell spends 75% (3/4) of its life in Interphase

Interphase occurs before mitosis begins Chromosomes are copied (# doubles) • Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase • Nucleus CELL MEMBRANE Cytoplasm

Interphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Prophase 1 st step in Mitosis begins (cell PREPARES to divide) • Centrioles (or poles) appear and begin to move to opposite end of the cell. • Sister Chromatids become visible. • Sister chromatids Centrioles Spindle fibers

Prophase Animal Cell Plant Cell Spindle fibers Centrioles Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Metaphase 2 nd step in Mitosis • Chromatids (or pairs of chromosomes) attach to the spindle fibers in the MIDDLE of the cell. Centrioles Spindle fibers

Metaphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Anaphase 3 rd step in Mitosis • Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Chromatids pull APART Centrioles Spindle fibers

Anaphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Telophase 4 th step in Mitosis Two new nuclei form. • Chromosomes appear as chromatin (threads rather than rods). • Mitosis ends. • Nuclei Chromatin Nuclei

Telophase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Cytokinesis occurs after mitosis • Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase Metaphase Telophase Prophase Anaphase Cytokinesis

Plant Mitosis -- Review Interphase Metaphase Telophase Prophase Anaphase Cytokinesis

Cell Cycle 21

- Cell Division The Cell Cycle 23 23

Count the number of cells in each stage Stage Interphase Prometaphase Metaphase Anaphase Telophase Cytokinesis Percent time in each stage

Cancer and Mitosis • • • It’s important that cells have a cycle of growth and death. Some cells fail to die and continually divide (Mitosis) Cells that continually divide and continue to build up. This is called a tumor A malignant tumors is cancerous. A benign tumor is non-cancerous.

Cancer & Mitosis If cells do not die, cancer is likely to develop (as the result tumors) • So, if cells continue to divide (undergo Mitosis), tumors and cancer will develop. • Apoptosis (programmed cell death) is necessary. A person’s health could be a stake if there is an error in Mitosis and cells fail to die. •

Examples of tumors These images are examples of tumors. • Cancer can take place on any part of the body. • The entire body is made of cells, and cancer starts with cells • Raise Cancer Awareness!

Cancer & Causes Genetics (heredity): some cancers are passed along family lines (breast cancer, prostate cancer) • Diet and obesity: colon cancer is caused by those who consume a diet high in fat • Environmental factors: 2 nd hand smoking-those who do not smoke can also get cancer because of those who smoke around them • Sun/UV rays: extended exposure to UV rays can cause skin cancer (melanoma)

Mitosis Animation http: //www. cellsalive. com/mitosis. htm Watch the animation! See how one cell divides into two!

The facts. . Males make sperm; females make eggs • Males go through meiosis until they are in their 70 s (men make sperm until they are elderly) • Ladies are born with the number of eggs they will have until menopause •

MEIOSIS vs. MITOSIS • Meiosis is how the body makes more gametes (sex cells). • Meiosis is NOT sexual reproduction. • Simply put, Meiosis is how we make sperm or eggs

Mitosis vs. Meiosis Mitosis Meiosis # of daughter cells 2 4 # of divisions 1 2 (Meiosis I & II) Chromosome number Diploid (2 n). Daughter cells have the same number of chromosomes as the parent cell Haploid (n). Daughter cells have half the number of chromosomes as parent cell. # of phases 4 -P, M, A, T 8 -11, Interphase, P 1, M 1, A 1, T 1, P 2, M 2, A 2, T 2 Type of cells produced Somatic (body cells) Gametes (sex cells)

Diploid vs. Haploid (chromosome number) Mitosis – diploid (2 n) Cells that divide and reproduce by MITOSIS are diploid. They have the same # of chromosomes as the parent cell Ex. If my liver cell has 46 chromosomes, the daughter cells will have 46 Meiosis – Haploid (n) Cells that divide and reproduce by MEIOSIS are HAPLOID. They have half the number of chromosomes as the parent cell. Ex. If an egg cell with 46 chromosomes goes through meiosis, the daughter cells will have 23 chromosomes

Examples of Diploid & Haploid Cells that are diploid reproduce by Mitosis. Example: a Liver cell that is reproducing through mitosis has 46 chromosomes. After Mitosis, the new daughter cells have 46 chromosomes. Cells that are haploid reproduce by Meiosis. Example: A man’s sperm has 46 chromosomes. After it goes through Meiosis, the daughter cells have 23 Gametes (sex cells) are HAPLOID (half)

Reinforcement Somatic = body cell Mitosis Diploid (2 n) Organism Gamete = sex cell Meiosis Haploid (n) Somatic Cell (Mitosis/Diploid) 2 n Gamete (Meiosis/Haploid) n Human 46 23 Garden pea 14 7 Fruit fly 8 4 Tomato 24 12 Dog 78 39 Chimpanzee 48 24 Leopard frog 26 13 Corn 20 10