Transcript Mitosis PP
Cell Reproduction QSR #6?? 1. _________ is the process by which cells divide to make more cells. 2. Your _______ cells divide most often while your ______ cells almost never divide. 3. In eukaryotic cells, chromosomes are found in the _______, but in prokaryotic cells they are found in the ____________. Cell Reproduction Cell division is the process by which cells reproduce Chromosomes: rod-shaped structures made of DNA and proteins Chromatids One single strand of the chromosome Held together by a centromere Cell Cycle Sequence of growth and division of a cell – the life cycle of a cell • Apoptosis: cellular death • Figure2.14 – In the embryo, fingers and toes are carved from webbed structures. In syndactyly, normal apoptosis, fails to carve the digits and webbing occurs CELL CYCLE A. Interphase 1. Resting phase because it is not dividing but it can be getting ready for division 2. performing everyday, normal functions 3. Can be divided into 3 stages • G1 •S • G2 B. G1 phase (Gap 1) 1.Growth phase 2.Grows rapidly 3.Carries out routine functions C. S phase Synthesis of DNA DNA is copied D. G2 phase (Gap 2) 1.Growth and Prep for Mitosis 2.organelles replicates (Doubling everything to prepare for mitosis) Cells divide at different rates: Cell type Approximate life span • Skin cells 2 weeks • Red blood cell 4 months • Liver cell 300-500 days • Intestinal cells 4-5 days • Muscle/other cells 16 years • Brain cells maybe never • ++++++++++++++++++++++++ Mitosis Process in which the nucleus of a cell divides into two nuclei, each with the same kind of chromosomes Interphase Chromosomes are replicated Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (sister chromosome) change to sister chromatids at the end of this phase • ***Remember: sister chromatids are held together by a centromere. The Stages of the cell cycle " Intellegent People Meet At Three O'Clock" Prophase Mitosis begins in this phase Centrioles (poles) appear and begin to move to opposite ends of cell. Spindle fibers form between the poles CHROMATIN condenses (coils up) into CHROMOSOMES The nuclear envelope starts to break up the Nucleolus disappears Metaphase Chromatids or pairs of chromosomes attach to the spindle fibers the Chromosomes line up at the “Middle” of the cell Anaphase Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell Centromere divides Telophase Two new nuclei form Chromosomes appear as chromatin (threads rather than rods) Nuclear envelope & nucleolus reforms Cytokinesis Division of the cytoplasm • Cell membrane moves inward to create two daughter cells – each with its own nucleus, identical chromosomes, and a total of 46 chromosomes each • Microscope: fish blastodisc (white fish) mitosis, onion tip mitosis, ascaris mitosis (parasite – intestinal roundworm) What phase and Why? What phase and Why? What phase and Why? What phase and Why? What phase and Why? Animated mitosis Mitosis, Mitosis Amelia Arellano Mitosis, Mitosis divided into four stages. Prophase, Metaphase, Anaphase, and Telephase. Prophase Prophase, Nucleus breaks down Metaphase, Metaphase Chromosomes line up in the center. Anaphase, Anaphase chromosomes moving to the opposite poles. Telophase, Telophase envelop forms And the spindle fiber begin to disappear Results of Mitosis Cells Tissues • muscle Organs • stomach Organ system • Digestive system Organism Stem cells Undifferentiated/ blank cell Can be developed into a variety of different cells Ex: embryonic stem cell can give rise to almost any cell Ex: Adult stem cells can give rise to related cells Why is stem cell research so important? Cell Differentiation Cells become specialized to perform specific functions…liver cells, skin cells, etc. Is based on location in an embryo • Outer– skin, brain, spinal cord • Middle– bones, muscles, kidneys • Inner– internal organs (pancreas, stomach, etc.) Asexual Reproduction Creation of an offspring with only one parent Ex: Binary Fission • a form of mitosis • – division into 2 equal parts **** (done in prokaryotic cells) **** Genetically identical to parent Ex: bacteria, some plants (stem cutting), sea star How is this different from sexual reproduction? ###################### QSR #8 1. Fill in the blanks to make the correct order: cells, ______, ______, systems, _________. 2. _____ cells are undifferentiated meaning they ____________ and can become other types of cells. 3. Cell differentiation depends on the location of the cells inside the ______. If they are in the outer layer they can become ________, middle layer________, inner layer________. 4. How are embryonic stem cells different from adult stem cells? Cancer Cancer • Uncontrolled Mitosis/Cell Division • Enzymes (proteins) monitor a cell’s progress from phase to phase Cancer Caused by damaged genes • Cancerous (malignant) cells form masses of tissue Tumors • Deprive normal cells of nutrients • Spread throughout the body Metastasis (cancer cells break away, get into blood stream, and spread) Cause of Cancers 1. Environmental factors (Carcinogens) – damage genes • Cigarette smoke, air pollutants, UV radiation 2. Genetic 3. Viral Infections 4. Different types of cancers in different parts of the world • Breast cancer High US Low Japan • Stomach cancer High in China Low in US Cancer Prevention Diet • Low in fat • High in fiber Cancer Prevention Healthy Exercise and NO TOBACCO products!!!! Vitamins and mineral • Yellow • Orange •A •C •E • Ca