Transcript CH10PPT
TAKE 3 MINUTES TO RESPOND TO ONE OF THE FOLLOWING QUESTIONS IN WRITING HERE ON YOUR OUTLINE GIVE AN EXAMPLE OF A TIME WHEN CELLS NEED TO DIVIDE GIVE AN EXAMPLE OF WHEN CELLS DIVIDE IN YOUR BODY HOW IS CANCER RELATED TO CELL DIVISION? 1. They have grown too large so…. the SURFACE AREA/VOLUME Ratio is too small 1. To allow an organism to grow and increase its SIZE 2. Cells have died and need to be REPLACED The Cell Cycle Cells may divide in days, weeks, or months, and some NEVER Divide. Cells divide during the period of the cell cycle known as MITOSIS WHAT KIND OF CELLS IN HUMANS RARELY DIVIDE? WHAT KIND OF CELLS IN HUMANS DIVIDE OFTEN? INTERPHASE Includes: G1- Growth Phase NORMAL Cell growth S - Synthesis REPLICATION of DNA G2 - Growth in preparation for cell division -cell organelles are DOUBLED CELL DVISION includes MITOSIS – DNA to each new cell(aka nuclear division CYOTKINESIS – Cell DIVIDES completely Inside the nucleus DNA condenses to form CHROMOSOMES Chromosomes are made from proteins called HISTONES and DNA together known as CHROMATIN Chromatin allows DNA to coil into NUCLEOSOMES Each chromosome consists of identical halves called SISTER CHROMATIDS Sister chromatids are joined together at the CENTROMERE Homologous Chromosomes Every SEXUALLY REPRODUCING organism gets two copies of each CHROMOSOME (1 from mom and 1 from dad) HUMAN cells each have 46 total chromosomes - 23 pairs (23n) Each pair of chromosome are called HOMOLOGOUS chromosomes Homologous chromosomes carry genes for the SAME traits AUTOSOMES are chromosomes 1-22 and DO NOT determine an individuals gender SEX chromosomes determine the GENDER of an organism XX = Female XY = Male WHAT IS THIS PERSONS GENDER? CARP- 104 ELEPHANT-56 PINEAPPLE-50 ADDER’S TONGUE FERN-1200 SHRIMP-92 BEIBER ? Diploid Cells: Cells with 2 copies of each chromosome The normal body cells are called SOMATIC cells, and they are all DIPLOID Like a nerve cell …. or muscle cells Haploid Cells: Cells with 1 copy of each chromosome SEX cells like the sperm & egg are haploid cells BINARY FISSION Prokaryotic Organisms: AUnicellular bacteria with no nucleus or membrane bound ORGANELLES Their DNA is found as One Circular Chromosome Their cells reproduce through BINARY FISSION DNA is replicated, cell doubles in size and splits Prophase Chromatin condenses & nucleus disappears SPINDLE fibers (microtubules) form & move chromosomes CENTROSOMES begin to migrate Metaphase Spindles align chromosomes in the middle of the cell aka METAPHASE PLATE Anaphase CENTROMERES are pulled apart by spindle fibers and sister chromatids split Chromatids move toward OPPOSITE poles Telophase Chromosomes arrive at opposite ends of cell NUCLEUS reappears Spindle disappears Cytokinesis Cell splits to form 2 new DAUGHTER CELLS http://www.youtube.com/watch?v=VlN7K1-9QB0&list=PLB261A77941D856DC This is mitosis in a PLANT cell This is mitosis in an ANIMAL cell In Animal Cells: A CLEAVAGE FURROW pinches one cell into 2 cells In Plant Cells: A CELL PLATE makes a new cell wall dividing the cells •Diploid Cells cells with 2 of each type of chromosome (1 from mom and 1 from dad) •n= number of pairs of chromosomes •Diploid Cells = 2n •Zygote = fertilized egg •Gametes= haploid sex cells •Fertilization= union of egg and sperm •Sexual Reproduction Parents generate specialized sex cells Getting from diploid to haploid cells: Meiosis Where does it occur in humans? Males: Testes Females: Ovaries Meiosis I 1 Diploid * cell splits into 2 haploid cells Meiosis II 2 haploid daughter cells undergo mitosis Forms 4 haploid sex cells Same as mitosis Prophase I Homologous chromosomes pair together a process called SYNAPSIS Each homologous pair of chromosomes is called a TETRAD PORTIONS of chromatids break off and attach to adjacent homologous chromatids this process is known as CROSSING OVER Crossing Over creates NEW gene combinations – the chromosomes of your sex cells are combinations of both your mom and dads!!! Metaphase I Homologous chromosomes line up in the MIDDLE of the cell Anaphase I Homologous CHROMOSOMES move to opposite poles of the cell Random separation of homologous chromosomes is called INDEPENDENT Assortment Telophase I Chromosomes reach opposite poles of the cell Cytokinesis begins 2 HAPLOID cells go through the process of mitosis & cell division The result of meiosis II is 4 HAPLOID cells Gamete Formation In males meiosis creates 4 SPERM cells (called spermatids) In females the cytoplasm is unevenly divided so that only 1 big cell THE OVUM is formed, along with 3 other cells known as POLAR bodies Meiosis Animation