Mitosis & MeiosisMitosis & Meiosis

Mitosis animation:Mitosis animation: http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related

Mitosis:Mitosis: If a cell wants to make a duplicate of itself, it If a cell wants to make a duplicate of itself, it

first must copy its DNA (part of a first must copy its DNA (part of a chromosome).chromosome).

The copies then must be separated & sorted The copies then must be separated & sorted into two sides of the cell.into two sides of the cell.

The cell then splits in two. Part of each parent The cell then splits in two. Part of each parent is carried to the two new cells. is carried to the two new cells.

Results in cells such as internal organs, skin, Results in cells such as internal organs, skin, bones, blood, etc. bones, blood, etc.

Meiosis:Meiosis: As in mitosis, if a cell wants to make a duplicate of itself, As in mitosis, if a cell wants to make a duplicate of itself,

it first must copy its DNA (part of a chromosome).it first must copy its DNA (part of a chromosome).

Results in reproductive cells (sperm, eggs, etc). Results in reproductive cells (sperm, eggs, etc).

Part of each parent is carried to the four new cells. Part of each parent is carried to the four new cells.

Meiosis has evolved to solve a problem.Meiosis has evolved to solve a problem.

The problem is this: some organisms have sex with other The problem is this: some organisms have sex with other organisms – that is, they combine their genes together organisms – that is, they combine their genes together (creating genetic diversity).(creating genetic diversity).

Why would this be a problem?Why would this be a problem?

This may you remember these terms:This may you remember these terms:

MITMITosis takes the cell and osis takes the cell and MMakes akes IIt t TTwo (diploid)wo (diploid)

MMeeiosis has to do with siosis has to do with seexx

From the cell’s point of view:From the cell’s point of view: mmITITosis results in osis results in IIdentical dentical TTwinswins mmEEioioSSis results in is results in EEgg and gg and SSperm (haploid)perm (haploid)

Clyde Freeman Herreid – Dept. of Biological Sciences: Buffalo State Univ. of New YorkClyde Freeman Herreid – Dept. of Biological Sciences: Buffalo State Univ. of New York

Mitosis: Meiosis:Mitosis: Meiosis:

Each resulting cell still has chromosomes from mom & dadEach resulting cell still has chromosomes from mom & dad

MitosisMitosis

Mitosis animations:Mitosis animations: http://www.youtube.com/watch?v=2WwIKdyBN_s&feature=related http://www.youtube.com/watch?v=VlN7K1-9QB0

VocabularyVocabulary

DiploidDiploid Haploid Haploid

InterphaseInterphase ProphaseProphase MetaphaseMetaphase Anaphase Anaphase TelophaseTelophase CytokinesisCytokinesis

Interphase Interphase occurs just before occurs just before Mitosis begins:Mitosis begins:

DNA is replicated along with organelles and other cellular components and the cell prepares for division.

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MitosisMitosis Interphase Interphase

Animal cellAnimal cell Plant cellPlant cell

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

11stst step in Mitosis: step in Mitosis: Prophase (preparation phase)Prophase (preparation phase)

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

The DNA recoils, and the chromosomes condense; the nuclear membrane disappears, and the mitotic spindles begin to form.

MitosisMitosis Prophase Prophase

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

Animal cellAnimal cell Plant cellPlant cell

22ndnd step in Mitosis: step in Mitosis:metaphase (organizational metaphase (organizational

phase)phase) The The

chromosomes chromosomes line up the line up the middle of the cell middle of the cell with the help of with the help of spindle fibers spindle fibers attached to the attached to the centromere of centromere of each replicated each replicated chromosome. chromosome.

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MitosisMitosis Metaphase Metaphase

Animal cellAnimal cell Plant cellPlant cell

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

33rdrd step in Mitosis: step in Mitosis: Anaphase (separation phase)Anaphase (separation phase)

The The chromosomes chromosomes split in the split in the middle and the middle and the sister chromatids sister chromatids are pulled by the are pulled by the spindle fibers to spindle fibers to opposite poles of opposite poles of the cell. the cell.

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MitosisMitosis Anaphase Anaphase

Animal cellAnimal cell Plant cellPlant cell

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

44thth step in Mitosis: step in Mitosis: TelophaseTelophase

The chromosomes, The chromosomes, along with the along with the cytoplasm and its cytoplasm and its organelles and organelles and membranes are divided membranes are divided into 2 portions. This into 2 portions. This diagram shows the end diagram shows the end of telophase.of telophase.

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MitosisMitosis Telophase Telophase

Animal cellAnimal cell Plant cellPlant cell

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

After Mitosis:After Mitosis: CytokinesisCytokinesis

The actual splitting ofThe actual splitting of

the daughter cells into the daughter cells into

two separate cells is two separate cells is

called cytokinesis andcalled cytokinesis and

occurs differently in occurs differently in

both plant and animalboth plant and animal

Cells.Cells.

Beginning of cytokinesis in a plant:

Beginning of cytokinesis in an animal:

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MeiosisMeiosis

Meiosis animation:Meiosis animation: http://www.youtube.com/watch?v=D1_-mQS_FZ0&NR=1

Vocabulary Vocabulary

Diploid Diploid Haploid Haploid Germ cellGerm cell Somatic cellSomatic cell

Interphase Interphase ProphaseProphase MetaphaseMetaphase Anaphase Anaphase TelophaseTelophase CytokinesisCytokinesis

Meiosis Meiosis InterphaseInterphase

Meiosis is preceded by interphase. The chromosomes have not yet condensed.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

MeiosisMeiosis Interphase Interphase

The chromosomes have replicated, and the chromatin begins to condense.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

MeiosisMeiosis Prophase I Prophase IThe chromosomes are completely condensed. In meiosis (unlike mitosis), the homologous chromosomes pair with one another and exchange genetic information

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Metaphase IMetaphase I

The nuclear The nuclear membrane dissolves membrane dissolves and the homologous and the homologous chromosomes attach chromosomes attach to the spindle fibers. to the spindle fibers. They are preparing to They are preparing to go to opposite poles. go to opposite poles.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Anaphase IAnaphase I

The chromosomes The chromosomes move to opposite move to opposite ends of the cell. ends of the cell.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Telophase I Telophase I && CytokinesisCytokinesis

The cell begins to The cell begins to divide into two divide into two daughter cells. It is daughter cells. It is important to important to understand that understand that each daughter cell each daughter cell can get any can get any combination of combination of maternal and maternal and paternal paternal chromosomes. chromosomes. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Prophase IIProphase II

The cell has The cell has divided into two divided into two daughter cells. daughter cells.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Metaphase IIMetaphase II

As in Meiosis I, the As in Meiosis I, the chromosomes line chromosomes line up on the spindle up on the spindle fibers. fibers.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Meiosis Anaphase IIAnaphase II

The two cells each The two cells each begin to divide. As begin to divide. As in Meiosis I, the in Meiosis I, the chromosomes chromosomes move to opposite move to opposite ends of each cell. ends of each cell.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Telophase II Telophase II && CytokinesisCytokinesis

With the formation With the formation of four cells, of four cells, meiosis is over. meiosis is over. Each of these Each of these prospective germ prospective germ cells carries half cells carries half the number of the number of chromosomes of chromosomes of somatic cells. somatic cells.

http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html