Cell Division

Mitosis

2

Cell Division Cell Division VocabularyVocabulary

Mitosis- is the process in which the Mitosis- is the process in which the nucleus divides to form two identical nucleus divides to form two identical nuclei.nuclei.

Chromosome- is a structure in the Chromosome- is a structure in the nucleus that contains hereditary nucleus that contains hereditary material.material.

Asexual Reproduction- a new Asexual Reproduction- a new organism is produced from ONE organism is produced from ONE organism.organism.

The Cell Cycle

The regular sequence of growth and division that cells undergo is known as the cell cycle.

Steps: Steps: Cells grow & function, DNA copied, Cells grow & function, DNA copied,

Cell grows and prepares for mitosis, Cell grows and prepares for mitosis, Mitosis happens, and Cytoplasm Mitosis happens, and Cytoplasm divides.divides.

The Phases

1. Interphase2. Prophase3. Metaphase4. Anaphase5. Telophase6. Cytokinesis

Interphase 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

Prophase Metaphase Anaphase Telophase

Prophase Threadlike

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

Chromatin Condenses to Form Chromosomes

The Chromosome 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 Chromosomes

line up at the center of the cell.

Each chromosome attaches to a spindle fiber at its centromere.

METAPHASE!!!!!!

Anaphase: Split Apart Chromosomes are

pulled apart by the spindle fibers and brought to each end of the cell.

Telophase: Two New Nuclei

Two new nuclei are formed Chromosomes begin to uncoil

Cytokinesis

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

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

Interphase: 21 hours Growth : 9 hours DNA Replication: 10 hours Preparation for Division: 2 hours

Mitosis: 1 hour Prophase Metaphase Anaphase Telophase

Sea Urchin Cell Cycle Sea Urchin Cell

Cycle takes 2 hours

Human Brain Cells

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

Review

Cellular Asexual Reproduction 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? Fission- an organism copies its genetic

material then divides into 2 identical organisms

Fission

Budding and regeneration

Budding- type of asexual reproduction made possible because of cell division. 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. Example: Starfish

Budding

The Steps of the Ladder 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. Adenine (A)2. Thymine (T)3. Guanine (G)4. Cytosine (C)

The Pairs

Adenine only pairs with Thymine Guanine only pairs with Cytosine

DNA Replication The ladder

unzips and the rungs find new pairs that are floating in the nucleus.