Cell Division Mitosis Cell Division Vocabulary Mitosis is

Cell Division Mitosis

Cell Division Vocabulary Mitosis- is the process in which the nucleus divides to form two identical nuclei. u Chromosome- is a structure in the nucleus that contains hereditary material. u Asexual Reproduction- a new organism is produced from ONE organism. u 2

The Cell Cycle n n The regular sequence of growth and division that cells undergo is known as the cell cycle. Steps: n Cells grow & function, DNA copied, Cell grows and prepares for mitosis, Mitosis happens, and Cytoplasm divides.

The Phases 1. 2. 3. 4. 5. 6. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Interphase n During interphase, the cell grows to its mature size, makes a copy of its DNA, and prepares to divide into two cells. DNA is Replicated (copied)

Next Stage is Mitosis: 4 Parts n n Prophase Metaphase Anaphase Telophase

Prophase n Threadlike chromatin in the cell’s nucleus begins to condense and coil.

Chromatin Condenses to Form Chromosomes

The Chromosome n n Chromosome: “X” shaped cell structure that directs cell activities and passes on traits to new cells. Each identical strand of the chromosome is called a chromatid. The strands are held together by a structure called the centromere. Chromatin: Loosely coiled DNA

Metaphase: Meet in the Middle n n Chromosomes line up at the center of the cell. Each chromosome attaches to a spindle fiber at its centromere.

METAPHASE!!!!!!

Anaphase: Split Apart n Chromosomes are pulled apart by the spindle fibers and brought to each end of the cell.

Telophase: Two New Nuclei n n Two new nuclei are formed Chromosomes begin to uncoil

Cytokinesis n n Animal Cells: Cell membrane pinches in between the two new cells. Plant Cells: Cell plate forms between the two cells. Cell Wall is too rigid to be pinched apart.

Homework n Illustrate the Six stages of the Cell Cycle. How you illustrate them or what materials you use is completely up to you. Just be sure that each stage is clearly illustrated and labeled.

Length of the Cell Cycle of a Human Liver Cell n Interphase: 21 hours n n Growth : 9 hours DNA Replication: 10 hours Preparation for Division: 2 hours Mitosis: 1 hour n n Prophase Metaphase Anaphase Telophase

Sea Urchin Cell Cycle n Sea Urchin Cell Cycle takes 2 hours

Human Brain Cells n Never divide, they remain in the first part of interphase for as long as they live!

Review

Cellular Asexual Reproduction n Requires one organism to reproduce Hereditary material will be IDENTICAL to the parent. Recall: Mitosis is the division of the nucleus. Question: What if an organism doesn’t have a nucleus? n Fission- an organism copies its genetic material then divides into 2 identical organisms

Fission

Budding and regeneration n Budding- type of asexual reproduction made possible because of cell division. n n The bud on the adult organism becomes large enough it breaks away to live on it’s own. Regeneration- the process that uses cell division to re-grow body parts. n Example: Starfish

Budding

The Steps of the Ladder n n Each rung of the DNA ladder is made up of a pair of molecules called nitrogen bases. There are four kinds of Nitrogen Bases: 1. 2. 3. 4. Adenine (A) Thymine (T) Guanine (G) Cytosine (C)

The Pairs n n Adenine only pairs with Thymine Guanine only pairs with Cytosine

DNA Replication n The ladder unzips and the rungs find new pairs that are floating in the nucleus.