CELL DIVISION Life Science

How do little elephants grow up to be BIG elephants?

WHY DO ANIMALS SHED THEIR SKIN?

CELL DIVISION Cell division: increases the number of cells and causes many- celled organisms to grow.  The new cells that are formed are called: daughter cells Life cycles: periods of formation, growth and development Nucleus: control center of the cell. Contains DNA  DNA makes up a Chromosome

genes

1) Reproduction 2) Growth 3) Repair Why do cells divide? How does the cell know how to divide? The DNA has the instructions for all of the cell’s activities.

1.Interphase - Preparation 2.Mitosis – Cell division 3.Cytokinesis – Splitting  Adult human cell: ~24 hrs hours in interphase 2 hours in mitosis 3 Parts How long does it take? The sequence of development and division of a cell

Animated Cell Cycle Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

StageDefinitionPictureDiagram 1.Interphase (I) NOT part of mitosis -chromosomes replicates -cell grows + rests

INTERPHASE Animal Cell Plant Cell Photographs from:

StageDefinitionPictureDiagram 1.Interphase (I) NOT Part of mitosis -Chromosomes replicate -cell grows + rests 2. Prophase (Play) -nuclear membrane and nucleolus disappears -spindle fibers start to form from centrioles CentromereChromosome CentrioleSpindle Fiber

PROPHASE Animal Cell Plant Cell Photographs from: Spindle fibers Chromosome

3. Metaphase (More) -double chromosomes attach to spindle -line up at equator (middle) Spindle Chromosomes Centriole Spindle

METAPHASE Animal Cell Plant Cell Photographs from:

3. Metaphase (More) -double chromosomes attach to spindle -line up at equator (middle) 4. Anaphase (At) -chromosomes separate towards ends of cell Chromatid Spindle Centriole

ANAPHASE Animal Cell Plant Cell Photographs from:

3. Metaphase (More) -double chromosomes attach to spindle -line up at equator (middle) 4. Anaphase (At) -chromosomes separate towards ends of cell 5. Telophase (The) -chromosomes reach opposite sides -cytoplasm divides (cytokinesis) (Circus) Cell Plate Chromosomes Cleavage Furrow Nuclear Membrane

TELOPHASE Animal Cell Plant Cell Photographs from:

REMEMBER! I Interphase P Prophase M Metaphase A Anaphase T Telophase C Cytokinesis IPMATC I Play M ore At T he Circus

BUT WHY DO CELLS DO THIS?

RESULTS OF MITOSIS 1.Produces two identical daughter cells 2.Daughter cells will have exactly the same number of chromosomes as the parent cell Ex. Human body cells have 46 chromosomes 3.This is a form of asexual reproduction

PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS Plant cell MitosisAnimal Cell Mitosis Cytokinesis (cytoplasm divides) Centrioles (spindle) Cleavage furrow Cell plate

PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS Plant cell MitosisAnimal Cell Mitosis Cytokinesis (cytoplasm divides) Cell plateCleavage furrow Centrioles (spindle) Cleavage furrow Cell plate

PLANT CELL MITOSIS VS ANIMAL CELL MITOSIS Plant cell MitosisAnimal Cell Mitosis Cytokinesis (cytoplasm divides) Cell plateCleavage furrow Centrioles (spindle) Not presentPresent + asters Cleavage furrow Cell plate

CANCER Cancer is uncontrolled cell division/cell growth Factors damaging genes that may lead to cancer: 1. Ultraviolet (UV) radiation 2. Chemicals/pollutants 3. Airborne particles (asbestos) 4. Diet 5. Radioactivity

ASEXUAL REPRODUCTION Asexual Reproduction:  Forms new organisms  Involves one parent  Genetic information identical to parent Ex. If mom has 12 chromosomes, baby has 12 chromosomes

BENEFITS: DISADVANTAGES:

MethodDefinitionExamples Binary Fission Parent cell divides into 2 equal size daughter Cells be.com/watch?v= 3cD3U2pgb5w Amoeba Euglena Bacteria

MethodDefinitionExamples Binary Fission Parent cell divides into 2 equal size daughter cells Amoeba Euglena Budding Parent cell divides into 2 unequal size daughter cells /watch?v=JZLHJZZZS-Y Yeast Hydra Bacteria Hydra

MethodDefinitionExample Sporulation m/watch?v=OrKr QI8Grb0 1,000’s of specialized cells that burst from a spore case Bread Mold Mushroom

MethodDefinitionExample Sporulation 1,000’s of specialized cells that burst from a spore case Bread Mold Regeneration /watch?v=f7cXeWxxfD4 Ability to re- grow body Parts -some re-grow parts -some re-grow new organisms Parts- Salamander/ lizard tail, lobster claws, starfish legs Whole Organism- Planaria Starfish from one leg and part of eye Mushroom

MethodDefinitionNaturalArtificial Vegetative Propagation Asexual reproduction in plants involves roots, stems, and leaves Natural and Artificial a.Tuber-white potatoes b. Bulb-tulip c. Runner- strawberry d. Rhizome-iris e. Grafting-apples f. Layering- raspberries g. Cutting-spider plant

MEIOSIS: SEXUAL REPRODUCTION  Formation of sex cells: sperm and egg  Sex cells have half the number of parent cells Ex. In humans sex cells have 23 chromosomes not 46 like all the other cells Why? 2 divisions  4 cells are produced

BENEFITS: DISADVANTAGES:

Parent Cell 1 st Division MEIOSIS – TWO DIVISIONS OF THE NUCLEUS 2 nd Division – 4 new daughter cells with ½ the # of chromosomes

FERTILIZATION Fertilization: the joining of an egg and a sperm from 2 different organisms of the same species  The cell that forms from fertilization is called the zygote.  Fertilization restores the number back to 46.