Cell Division. Occurs in the nucleus of a cell Occurs in the nucleus of a cell The cell must make a copy/replicatation of its DNA -genetic code (part

Cell DivisionCell Division

Cell DivisionCell Division

Occurs in the nucleus of a cellOccurs in the nucleus of a cell The cell must make a copy/replicatation The cell must make a copy/replicatation

of its DNA -genetic code (part of a of its DNA -genetic code (part of a chromosome)chromosome)

Chromosome: an organized structure of Chromosome: an organized structure of DNA.DNA.

Humans have 46 chromosomes(23pairs) Humans have 46 chromosomes(23pairs) 1 is the Sex Chromosome (boy/girl) 1 is the Sex Chromosome (boy/girl)

Mitosis:Mitosis: -A process of asexual reproduction (1parent)-A process of asexual reproduction (1parent)

# of divisions=1# of divisions=1 # of cells produced=2 (exact copies)# of cells produced=2 (exact copies) Makes internal organs, skin, bones, blood, Makes internal organs, skin, bones, blood,

etc. etc.

Meiosis:Meiosis: -A process of sexual reproduction (2 parents)-A process of sexual reproduction (2 parents)

# of divisions=2# of divisions=2 # of cells produced=4 (parts of each parent)# of cells produced=4 (parts of each parent) Results in reproductive cells (sperm, eggs, etc). Results in reproductive cells (sperm, eggs, etc).

Mitosis: Meiosis:Mitosis: Meiosis:

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

MutationsMutations

““Mistakes” Mistakes” in cellsin cells Caused by Caused by

-problems in cell copies of DNA in cell division-problems in cell copies of DNA in cell division -DNA damage from UV light, radiation, or -DNA damage from UV light, radiation, or

other chemicals.other chemicals. Can be passed on through the parent cell.Can be passed on through the parent cell.

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

MitosisMitosis

Mitosis animations:Mitosis animations: 2 minute video clip2 minute video clip http://highered.mcgraw-hill.com/sites/http://highered.mcgraw-hill.com/sites/

0072495855/student_view0/chapter2/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.htmlanimation__mitosis_and_cytokinesis.html

Interphase:Interphase:

-occurs just before 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

Prophase (preparation phase)Prophase (preparation phase)


-1st step in Mitosis

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

MitosisMitosis Prophase Prophase



Metaphase Metaphase (organizational phase)(organizational phase)

-2-2ndnd step in step in Mitosis Mitosis

--The chromosomes The chromosomes line up the middle line up the middle of the cell with the of the cell with the help of spindle help of spindle fibers attached to fibers attached to the centromere of the centromere of each replicated each replicated chromosome. chromosome. http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm

MitosisMitosis Metaphase Metaphase



Anaphase (separation phase)Anaphase (separation phase)

-3-3rdrd Step in Mitosis Step in Mitosis -The chromosomes split in -The chromosomes split in

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


MitosisMitosis Anaphase Anaphase



TelophaseTelophase

-4-4thth Step in Mitosis Step in Mitosis

-The chromosomes, along -The chromosomes, along with the cytoplasm and with the cytoplasm and its organelles and its 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.


MitosisMitosis Telophase Telophase



CytokinesisCytokinesis

-After Mitosis-After Mitosis

-The actual -The actual splitting of the splitting of the daughter cells daughter cells into two into two separate cellsseparate cells

-occurs differently -occurs differently in in

both plant and both plant and animalanimal

Cells.Cells.

Beginning of cytokinesis in a plant:

Beginning of cytokinesis in an animal:


MeiosisMeiosis Meiosis animation:Meiosis animation: 2 minute overview of diff. between mitosis and meiosis2 minute overview of diff. between mitosis and meiosis

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/chapter2/animation__comparison_of_meiosis_and_mitosis__quiz_2_.htmlanimation__comparison_of_meiosis_and_mitosis__quiz_2_.html

Really Good real time cell divisionReally Good real time cell division

http://dsc.discovery.com/tv-shows/other-shows/videos/assignment-http://dsc.discovery.com/tv-shows/other-shows/videos/assignment-discovery-shorts-cell-division.htmdiscovery-shorts-cell-division.htm

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.


MeiosisMeiosis Prophase I Prophase I

The chromosomes are completely condensed. In meiosis (unlike mitosis), the homologous chromosomes pair with one another


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.


Meiosis Meiosis Anaphase IAnaphase I

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


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.


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.


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.


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.


Yvonne NormanYvonne Norman

G410 (Life Sciences for Middle School Educators)G410 (Life Sciences for Middle School Educators)

Senior – Portland State UniversitySenior – Portland State University

February 2009February 2009

Documents

Cell Division. Occurs in the nucleus of a cell Occurs in the nucleus of a cell The cell must make a copy/replicatation of its DNA -genetic code (part