Mitosis & Meiosis Mitosis animation:

Mitosis: If a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). If a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). The copies then must be separated & sorted into two sides of the cell. The copies then must be separated & sorted into two sides of the cell. The cell then splits in two. Part of each parent is carried to the two new cells. The cell then splits in two. Part of each parent is carried to the two new cells. Results in cells such as internal organs, skin, bones, blood, etc. Results in cells such as internal organs, skin, bones, blood, etc.

Meiosis: As in mitosis, if a cell wants to make a duplicate of itself, it first must copy its DNA (part of a chromosome). As in mitosis, if a cell wants to make a duplicate of itself, 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 organisms – that is, they combine their genes together (creating genetic diversity). The problem is this: some organisms have sex with other organisms – that is, they combine their genes together (creating genetic diversity). Why would this be a problem? Why would this be a problem?

This may you remember these terms: MITosis takes the cell and Makes It Two (diploid) MITosis takes the cell and Makes It Two (diploid) Meiosis has to do with sex Meiosis has to do with sex From the cell’s point of view: From the cell’s point of view: mITosis results in Identical Twins mITosis results in Identical Twins mEioSis results in Egg and Sperm (haploid) mEioSis results in Egg and Sperm (haploid) Clyde Freeman Herreid – Dept. of Biological Sciences: Buffalo State Univ. of New York

Mitosis: Meiosis: Each resulting cell still has chromosomes from mom & dad

Mitosis Mitosis animations: Mitosis animations:

Interphase occurs just before Mitosis begins: DNA is replicated along with organelles and other cellular components and the cell prepares for division.

Mitosis Interphase Animal cell Plant cell Photographs from:

1 st step in Mitosis: Prophase (preparation phase) The DNA recoils, and the chromosomes condense; the nuclear membrane disappears, and the mitotic spindles begin to form.

Mitosis Prophase Photographs from: Animal cell Plant cell

2 nd step in Mitosis: metaphase (organizational phase) The chromosomes line up the middle of the cell with the help of spindle fibers attached to the centromere of each replicated chromosome. The chromosomes line up the middle of the cell with the help of spindle fibers attached to the centromere of each replicated chromosome.

Mitosis Metaphase Animal cell Plant cell Photographs from:

3 rd step in Mitosis: Anaphase (separation phase) The chromosomes split in the middle and the sister chromatids are pulled by the spindle fibers to opposite poles of the cell. The chromosomes split in the middle and the sister chromatids are pulled by the spindle fibers to opposite poles of the cell.

Mitosis Anaphase Animal cell Plant cell Plant cell Photographs from:

4 th step in Mitosis: Telophase The chromosomes, along with the cytoplasm and its organelles and membranes are divided into 2 portions. This diagram shows the end of telophase. The chromosomes, along with the cytoplasm and its organelles and membranes are divided into 2 portions. This diagram shows the end of telophase.

Mitosis Telophase Animal cell Plant cell Photographs from:

After Mitosis: Cytokinesis The actual splitting of the daughter cells into two separate cells is called cytokinesis and occurs differently in both plant and animal Cells. Beginning of cytokinesis in a plant: Beginning of cytokinesis in an animal:

Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC I Pray More At The Church Julie Camp’s mitosis power point -

Meiosis Meiosis animation: Meiosis animation:

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

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

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

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

Meiosis Anaphase I The chromosomes move to opposite ends of the cell.

Meiosis Telophase I & Cytokinesis The cell begins to divide into two daughter cells. It is important to understand that each daughter cell can get any combination of maternal and paternal chromosomes.

Meiosis Prophase II The cell has divided into two daughter cells.

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

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

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

Results of Mitosis First, it is the division of a nucleus Second, it produces two nuclei that are identical to each other and the original nucleus Each new nucleus has the same number and type of chromosomes

Every cell in your body, except sex cells, has a nucleus with 46 chromosomes- 23 pairs Every cell in your body, except sex cells, has a nucleus with 46 chromosomes- 23 pairs Each of the trillions cells in your body, except sex cells, has a copy of the same hereditary material Each of the trillions cells in your body, except sex cells, has a copy of the same hereditary material

Cell division allows growth and replaces worn out or damaged cells Cell division allows growth and replaces worn out or damaged cells If you cut yourself, the wound heals because cell division replaces damaged cells. If you cut yourself, the wound heals because cell division replaces damaged cells. Another way some organisms use cell division is to produce new organisms Another way some organisms use cell division is to produce new organisms

Reproduction Reproduction Reproduction is the process by which an organism produces others of its same kind Reproduction is the process by which an organism produces others of its same kind Among living organisms, there are two types of reproduction- sexual and asexual Among living organisms, there are two types of reproduction- sexual and asexual

Asexual Reproduction A new organism, sometimes more than one, is produced from one organism A new organism, sometimes more than one, is produced from one organism The new organism will have hereditary material identical to the hereditary material of the parent organism The new organism will have hereditary material identical to the hereditary material of the parent organism

Cellular Asexual Reproduction Organisms with eukaryotic cells asexually reproduce by cell division. Organisms with eukaryotic cells asexually reproduce by cell division. A sweet potato growing in a jar of water is an example of asexual reproduction A sweet potato growing in a jar of water is an example of asexual reproduction Recall that mitosis is the division of a nucleus. Recall that mitosis is the division of a nucleus. Bacteria does not have a nucleus so they can’t use mitosis Bacteria does not have a nucleus so they can’t use mitosis

Budding and Regeneration A new organism is growing from the body of the parent organism A new organism is growing from the body of the parent organism Budding is a type of asexual reproduction made possible because of cell division. Budding is a type of asexual reproduction made possible because of cell division. Some organisms can regrow damaged or lost body parts Some organisms can regrow damaged or lost body parts

Regeneration Regeneration is the process that uses cell division to regrow body parts Regeneration is the process that uses cell division to regrow body parts Sponges, planaria, sea stars and some other organisms can use regeneration for asexual reproduction Sponges, planaria, sea stars and some other organisms can use regeneration for asexual reproduction

Sexual Reproduction Another way that a new organism can be produced, Another way that a new organism can be produced, Two sex cells, an egg and a sperm, come together Two sex cells, an egg and a sperm, come together Sex cells are formed from cells in reproductive organs Sex cells are formed from cells in reproductive organs

Fertilization The joining of the egg and sperm….the cell forms a zygote The joining of the egg and sperm….the cell forms a zygote Generally, the egg and sperm come from two different organisms of the same species Generally, the egg and sperm come from two different organisms of the same species Following fertilization, cell division begins Following fertilization, cell division begins

Vocabulary for this section Diploid Diploid Haploid Haploid DNA DNA Genome Genome Gene Gene Nucleus Nucleus Organelle Organelle Nuclear envelope Nuclear envelope Cytoplasm Cytoplasm Asexual reproduction Asexual reproduction Sexual reproduction Sexual reproduction Fission Fission Cell division Cell division Cell Cell Organism Organism Replication Replication Cancer Cancer Cell cycle Cell cycle Phase Phase Reproduction Reproduction Offspring Offspring Meiosis Meiosis Mitosis Mitosis Regeneration Regeneration Budding Budding spore spore