Cell Reproduction/Mitosis Chapter 8

What you need to know! Mitotic Cell division results in genetically identical daughter cells The mitotic phase alternates with interphase in the cell cycle

Cell Division Life depends on the ability of cells to reproduce/copy Cell Division = 1 mother cell divides into 2 daughter cells Unicellular organisms cell division = reproduction Prokaryotes, Protists Bacteria = binary fission

Cell Division Multicellular organism cell division = growth and development, repair and replacement Protists, fungi, plants and animals 2 categories of cells: Somatic Cells: Body cells of an organism that do all the daily function of the organism (mitosis) Germ Cells: reproductive cells like eggs and sperm (meiosis)

Cell Cycle Interphase Mitosis (M): nuclear division G1: Growth, development, organelle production, etc. S: DNA replication G2: continued growth and preparation for division (centrosomes/centrioles duplicate) Mitosis (M): nuclear division Cytokinesis: cell splits into two cells

DNA Chromatin (spaghetti): spread out DNA-histone complex Chromosome (X’s): condensed strands of DNA

DNA Diploid indicates somatic (body) cells Humans have 23 pairs of chromosomes (2n) Haploid indicates gametes (sex cells) Humans have 23 chromosomes (1n or n)

Mitosis: Nuclear Division Each chromosome contains thousands of genes, each necessary to the proper functioning of the organism. Humans have ~120,000 genes spread over 46 chromosomes in each somatic cell.

Mitosis During Mitosis all access to the DNA stops as chromatin coils up and condenses into visible chromosomes Each replicated chromosome is composed of 2 identical parts (sister chromatids) held together by a centromere

Mitosis Sister chromatids are pulled apart during mitosis, and partitioned into 2 daughter cells Result of mitosis & cytokenesis: 2 daughter cells genetically identical to the parent cell.

Phases of Mitosis Prophase: Chromosomes condense; centrosomes are pushed apart by growing spindle fibers; nuclear envelope disintegrates

Stages of Mitosis Prometaphase: the 2 centromeres of each chromosome attach to one kinetochore spindle fiber; centrosomes move to opposite poles Kinetochore spindle fiber Non Kinetochore spindle fiber

Stages of Mitosis Metaphase: Chromosomes line up at the metaphase plate (equator); centrosomes are at opposite poles

Stages of Mitosis Anaphase: Chromosomes separate (shortening of kinetochore spindle fibers); cell elongates (lengthening of non-kinetochore spindle fibers) Non Kinetochore spindle fiber Kinetochore spindle fiber

Stages of Mitosis Telophase: Chromosomes immediately uncoil and resume transcription activities; spindle proteins disassemble; nuclear envelope reassembles

Mitosis Animation http://vcell.ndsu.nodak.edu/animations/mitosis/movie-flash.htm

Cytokinesis Animal Cells: Cleavage furrow Made by microfilaments (actin fibers) A drawstring around the middle of the cell Cell pinches off into 2 daughter cells Plant Cells: No cleavage furrow Cell plate grows through divided cell