Cell Cycle Steps to Mitosis

Types of Cells Review Prokaryotes – No nucleus OR membrane bound organelles Examples: Bacteria Eukaryotes – Has a nucleus AND membrane bound organelles Examples: Plants and animals

Prokaryotes Prokaryotes – Lack nucleus Has a single chromosome Reproduces by binary fission Includes bacteria

What is binary fission? Type of reproduction used by bacteria Cells increase their cell mass slightly DNA and cell components are replicated Each cell divides into 2 daughter cells

Eukaryotes Contains a nucleus and membrane bound organelles Asexually reproduce cells by a process called mitosis

2 Reasons why cells divide DNA OVERLOAD 1. _____________________ As cell grows bigger demand on DNA “genetic library” becomes too great Ex: Small town library has 1000 books. As town grows and more people borrow books, there may be a waiting list to read the most popular titles http://www.adc.state.az.us/images/Off-Library.JPG

2 Reasons why cells divide Material exchange can’t keep up 2. _____________________ As cell grows bigger demand for transport across membrane is too great

More on Why Cells Divide Ability to transport of oxygen, food, waste across cell membrane depends on _______________ Need for these depends on ___________ SURFACE AREA CELL VOLUME As cell grows these DON’T increase at the same rate Surface-Area to Volume Ratio Animation

Ratio of Surface Area to Volume in Cells Cell Size Surface Area (length x width x 6) Volume (length x width x height) Ratio of Surface Area to Volume

BIGGER CELLS NEED MORE FOOD and OXYGEN, but CAN’T TRANSPORT IT FAST ENOUGH or IN BIG ENOUGH QUANTITIES! http://www.animationlibrary.com

mainly by increasing cell number Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG Image by Riedell Multicellular organisms grow mainly by increasing cell number

DNA CAN BE: SPREAD OUT IN NON-DIVIDING CELLS SCRUNCHED UP IN DIVIDING CELLS CHROMATIN CHROMOSOMES

DNA in PROKARYOTES BACTERIAL DNA is CIRCULAR HAVE ONE CHROMOSOME NO NUCLEUS; ATTACHED TO CELL MEMBRANE http://www.origin-life.gr.jp/3202/3202121/fig6.jpg

DNA in EUKARYOTES (Plants & Animals) DNA is ROD-SHAPED CHROMOSOMES MANY PAIRS FOUND IN NUCLEUS http://cellbio.utmb.edu/cellbio/chrom2.jpg

Chromosome structure SISTER CHROMATIDS CENTROMERE HOMOLOGOUS ___________________ 2 identical arms __________________ constricted area holds chromatids together CENTROMERE HOMOLOGOUS __________________ PAIR 2 of each chromosome (one from mom; one from dad)

HOMOLOGOUS CHROMOSOMES SAME SIZE SAME SHAPE CARRY GENES for the SAME TRAITS BUT ______________! (Don’t have to have the SAME CHOICES) NOT IDENTICAL http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

CELL DIVISION in PROKARYOTES Bacteria reproduce using __________________________________ BINARY FISSION http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg

Cell Cycle __________= series of events that cells go through as they grow and develop

Cell Cycle Stages in growth & division G1 Phase (Gap 1) S Phase (Synthesis) G2 Phase (Gap 2) M Phase (Mitosis) Cytokinesis

CELL CYCLE INTERPHASE – non-dividing phase G1- Grow bigger Cell is “doing its job” DNA is spread out as chromatin S - Synthesis (copy DNA) & chromosomal proteins G2- Grow bigger, make organelles & molecules needed for cell division

CELL DIVISION MITOSIS – Nuclear division Prophase Metaphase Anaphase Telophase Cytokinesis – Cytoplasm divides G0 – cell stops dividing (Ex: nerve cell)

Mitosis has no beginning and no end Life Cycle of A Cell Mitosis has no beginning and no end

Stages of Mitosis Interphase – “Resting Phase” Cells carrying on normal activities Chromosomes are not visible Cell metabolism is occurring Occurs before mitosis

Cells Undergoing Mitosis

PROPHASE DNA scrunches into chromosomes Pearson Education Inc publishing as Pearson Prentice Hall PROPHASE 1st dividing phase http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html DNA scrunches into chromosomes Centrioles appear in centrosome region & move to poles Nuclear membrane & nucleolus disappear Spindle fibers form & attach to chromosomes

________ region organizes spindle CENTROSOME Spindle MICROTUBULES are part of cytoskeleton http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm

METAPHASE middle Chromosomes line up in ___________ Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

ANAPHASE Centromeres split Centrioles pull chromatids_______ apart Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG

two See ______ nuclei Nuclear membrane & nucleolus return TELOPHASE (reverse prophase steps) two See ______ nuclei Nuclear membrane & nucleolus return Chromosomes spread out as chromatin Centrioles disappear Spindle fibers disappear Images from: Pearson Eduction Ince; Publishing as Pearson Prentice Hall http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html

CYTOKINESIS Cytoplasm splits into 2 cells CLEAVAGE FURROW ANIMAL CELLS pinch cytoplasm in two with a ______________________ CLEAVAGE FURROW

CYTOKINESIS Cytoplasm splits into 2 cells PLANT CELLS can’t pinch because they have a sturdy ____________ Plant cells separate cytoplasm by growing a _______________ down the middle. CELL WALL CELL PLATE http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html

Mitosis Fun Mr. Parr's Version - Mitosis Song Mitosis Animation Mitosis Animation - Via YouTube

Concept Map Cell Cycle includes is divided into is divided into

Concept Map Cell Cycle Section 10-2 includes M phase (Mitosis) Interphase is divided into is divided into G1 phase S phase Prophase G2 phase Metaphase Telophase Anaphase