Mitosis September (5*3)+2-9/3, 2009  Objectives:  Describe the five phases of mitosis.  Explain why mitosis produces two identical cells.  Catalyst:  How do organisms grow?  What happens in interphase?  Homework:  Finish independent practice worksheet

Definitions – In case you missed them…  Sex cells = sperm and eggs  Somatic cells = everything else in your body  DNA = instructions for how a cell should run (it’s what makes you “you”)  Chromosome = coils of DNA. Look like Xs.

Catalyst Review  How do organisms grow?  They create new cells!  One cell divides into two  The new cell is an exact copy of the previous cell  This process is called mitosis

Catalyst Review  What happens in interphase?  Cells do their normal cell things Heart cells beat Plant cells photosynthesize Eye cells let you see Skin cells protect you from stuff outside your body  When cells are ready to divide, make an exact copy of their DNA

Catalyst Review  Remember…  Somatic (body) cells normally have 23 pairs of chromosomes 2N = 2 PAIRS  When they are ready to divide, they make copies of their DNA 4N = 4 PAIRS

Mitosis CHALLENGE! Are you up for it?  Arrange the four pictures in order that makes sense to you and your group!  There will be a prize for the group that gets the correct answer AND can explain why they chose this order.  Remember: In mitosis, a somatic cell creates an exact copy of itself.

Pull out the sheet you picked up this morning  You can take notes on this sheet.

Stage #1: Interphase  Normally cells are 2N (two copies of each chromosome)  When cells are ready to divide, the cell’s DNA doubles  Cell becomes 4N (four copies of each chromosome)

Chromosome Pairs  In interphase, chromosomes duplicate and form pairs  When a chromosome is in a pair, it is called a chromatid

Stage #1: Interphase

Phase #2: Prophase  Chromatids attach to each other  Centrioles move to opposite ends of the cell  Barrel-shaped organelle, you’ll see what it does in a second  Nuclear membrane breaks  Allows chromatids to move freely

 Sister chromatids line up in the center of the cell  Spindles shoot out of centrioles, and attach to sister chromatids  WHY would sister chromatids line up at the metaphase plate?!?!?! Phase #3: Metaphase

Animal Cell Plant Cell Photographs from: Phase #3: Metaphase

 Spindles pull sister chromatids apart to opposite ends of the cell  WHY would sister chromatids move to opposite ends of the cell?!?!?! Phase #4: Anaphase

Animal Cell Plant Cell Photographs from: Phase #4: Anaphase

 Nuclear membrane reforms  Spindle breaks apart  Cleavage furrow forms, “pinching” the cell in half  WHY would the cleavage furrow split the cell in half?!?!?! Phase #5: Telophase

Phase #1: Interphase Now we have two identical cells!!!

Animal Cell Plant Cell Photographs from: Phase #5: Telophase

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

WOW MR. JHAVERI YOU RULE!!! THANKS MR. JHAVERI FOR THE SWEET MOVIE!!!

I Interphase P Prophase M Metaphase A Anaphase T Telophase IPaint M any Amazing T-shirts I Paint M any Amazing T-shirts

WHO’S PAYING ATTENTION?  What type of cell does mitosis occur in?  What is the starting point of mitosis? What are the end products of mitosis?  What are the names of the stages of mitosis?

Guided Practice  Today, we will move around the classroom to answer questions on the board. You have 10 seconds to get to each spot.  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase Chromosomes line up in the middle of the cell

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase Cleavage furrow forms, pinching the cell in half.

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase In between cell divisions, when the cell does its thaaaaang.

What phase is this?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase When chromosomes are pulled to opposite sides of the cell.

What phase occurs AFTER the following?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase Chromatids attach to each other and centrioles begin to move to opposite sides of the cell.

What phase occurs AFTER the following?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase Chromosomes line up in the middle of the cell.

What phase occurs AFTER the following?  -In the middle of the classroom- Interphase  -By the group folders- Prophase  -By the computer- Metaphase  -By Mr. McKnight’s room- Anaphase  -By the door- Telophase Chromatids are pulled apart to opposite sides of the cell.

Conclusion  I Paint Many Amazing T-shirts!  Prophase- chromatids attach to each other  Metaphase- chromatids line up in the middle of the cell  Anaphase- chromatids are pulled to opposite ends of the cell  Telophase- cleavage furrow forms and pinches off two cells  Mitosis ends up with two identical cells!

Exit Question  What are the phases of mitosis in order?  What must occur before mitosis (think DNA)?

Stage #1: Interphase  ________________ ________________ ________________  ________________ ________________ ________________ Cell is _____N

Phase #2: Prophase  ______________________ ______________________ ______________________ Cell is _____N

 _________________ _________________ _________________ _________________ _________________ Phase #3: Metaphase Cell is _____N

 __________________ __________________ __________________ __________________ __________________ Phase #4: Anaphase Cell is _____N

 ____________________ ____________________ ____________________  ____________________ ____________________ ____________________ ____________________ Phase #5: Telophase Cell is _____N

_______________________________________________________ _____________________________ Remember!