Cell DivisionMitosis: the process by which cells reproduce themselves, resulting in

daughter cells that contain the same amount of genetic material as the

parent cell.

Simply put…how one cell becomes two

• Cell Division refers to the ENTIRE process• Mitosis is a phase of the cell cycle• Mitosis, itself, has four phases (Prophase,

Metaphase, Anaphase, Telophase)

Animated Mitosis Cyclehttp://www.cellsalive.com/mitosis.htm

• Interphase

• Prophase

• Metaphase

• Anaphase

• Telophase

• Cytokinesis

Cell Type Life Cycle (how often they go through

Mitosis)

Intestine lining Every 2-3 days

Stomach lining Every 5 days

Skin cells Every 28 days

Liver cells Every 42 days

Bone cells Every 90 days

Red blood cells Every 120 days

OUR BODIES MAKE 1,000,000,000 (ONE BILLION) CELLS EVERY DAY????

OUR CELLS ARE CONSTANTLY DIVIDING.

MITOSIS IS HOW WE MAKE NEW CELLS, AND GET RID OF OLD, DEAD CELLS.

The Cell Cycle (aka Cell Division and Mitosis) is how we make new body cells.

Our body cells are called “somatic” (SO-mat-TICK)

All cells in our body (somatic cells) reproduce through MITOSIS, except our GAMETES (or sex cells)—meaning sperm or eggs. Sperm and eggs reproduce through MEIOSIS

Has 3 phases G1 (growth) S (DNA synthesis, DNA

replication) G2 (growth) A cell spends 75% (3/4) of

its life in Interphase

• Chromosomes are copied (# doubles)• Chromosomes appear as threadlike coils

(chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase

CELL MEMBRANENucleus

Cytoplasm

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

• Mitosis begins (cell PREPARES to divide)• Centrioles (or poles) appear and begin to

move to opposite end of the cell. • Sister Chromatids become visible.

CentriolesSister chromatids

Spindle fibers

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Spindle fibers

Centrioles

• Chromatids (or pairs of chromosomes) attach to the spindle fibers in the MIDDLE of the cell.

Centrioles

Spindle fibers

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

• Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Chromatids pull APART

Centrioles

Spindle fibers

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

• Two new nuclei form. • Chromosomes appear as chromatin

(threads rather than rods).• Mitosis ends.

NucleiNuclei

Chromatin

Animal Cell Plant Cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

• Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review

Interphase

                                        

                    

Prophase

                                       

                     

Metaphase

                                        

                    

Anaphase

                                       

                     

Telophase

                                        

                    

Cytokinesis

                                       

                     

Plant Mitosis -- Review

Interphase

                                                 

           

Prophase

                                                

            

Metaphase

                                                 

           

Anaphase

                                                

            

Telophase

                                                 

           

Cytokinesis

                                                

            

21

23

- Cell Division

23

Count the number of cells in each stage

Stage Percent time in each stage

Interphase

Prophase

Prometaphase

Metaphase

Anaphase

Telophase

Cytokinesis

• It’s important that cells have a cycle of growth and death.

• Some cells fail to die and continually divide (Mitosis)

• Cells that continually divide and continue to build up.

• This is called a tumor • A malignant tumors is cancerous.• A benign tumor is non-cancerous.

• If cells do not die, cancer is likely to develop (as the result tumors)

• So, if cells continue to divide (undergo Mitosis), tumors and cancer will develop.

• Apoptosis (programmed cell death) is necessary. A person’s health could be a stake if there is an error in Mitosis and cells fail to die.

• These images are examples of tumors.

• Cancer can take place on any part of the body.

• The entire body is made of cells, and cancer starts with cells

Raise Cancer Awareness!

• Genetics (heredity): some cancers are passed along family lines (breast cancer, prostate cancer)

• Diet and obesity: colon cancer is caused by those who consume a diet high in fat

• Environmental factors: 2nd hand smoking-those who do not smoke can

also get cancer because of those who smoke around them

Sun/UV rays: extended exposure to UV rays can cause skin cancer (melanoma)

http://www.cellsalive.com/mitosis.htm

Watch the animation! See how one cell divides into two!

• Males make sperm; females make eggs

• Males go through meiosis until they are in their 70s (men make sperm until they are elderly)

• Ladies are born with the number of eggs they will have until menopause

• Meiosis is how the body makes more gametes (sex cells).

• Meiosis is NOT sexual reproduction.• Simply put, Meiosis is how we make

sperm or eggs

Mitosis Meiosis

# of daughter cells 2 4

# of divisions 1 2 (Meiosis I & II)

Chromosome number

Diploid (2n). Daughter cells have the same number of chromosomes as the parent cell

Haploid (n). Daughter cells have half the number of chromosomes as parent cell.

# of phases 4-P, M, A, T 8-11, Interphase, P1, M1, A1, T1, P2, M2, A2, T2

Type of cells produced

Somatic (body cells)

Gametes (sex cells)

Mitosis – diploid (2n) Cells that divide and

reproduce by MITOSIS are diploid.

They have the same # of chromosomes as the parent cell

Ex. If my liver cell has 46 chromosomes, the daughter cells will have 46

Meiosis – Haploid (n)Cells that divide and

reproduce by MEIOSIS are HAPLOID.

They have half the number of chromosomes as the parent cell.

Ex. If an egg cell with 46 chromosomes goes through meiosis, the daughter cells will have 23 chromosomes

Cells that are diploid reproduce by Mitosis.

Example: a Liver cell that is reproducing through mitosis has 46 chromosomes. After Mitosis, the new daughter cells have 46 chromosomes.

Cells that are haploid reproduce by Meiosis.

Example: A man’s sperm has 46 chromosomes. After it goes through Meiosis, the daughter cells have 23

Gametes (sex cells) are HAPLOID (half)

Somatic = body cell

Mitosis Diploid (2n)

Gamete = sex cell Meiosis Haploid (n)

Organism Somatic Cell (Mitosis/Diploid) 2n

Gamete (Meiosis/Haploid) n

Human 46 23

Garden pea 14 7

Fruit fly 8 4

Tomato 24 12

Dog 78 39

Chimpanzee 48 24

Leopard frog 26 13

Corn 20 10