MITOSIS

•What is Mitosis?????

•Mitosis is the process in which a cell divides to generate another identical cell.

Mitosis and Trait Diversity

• The new cells have exact copies of the nucleus so the cells have identical DNAs.

•Mitosis does not contribute to trait diversity in the population

Why is mitosis important?

• Reproduction of unicellular organisms – asexual reproduction

• Growth for multicellular organisms – cells split in two creating new cells

• Regeneration of body parts and damaged cells – cells split in two creating new cells

• Regeneration of skin – heals wounds

What cells go through Mitosis????

Multicellular Organisms have two types of cells:

a) Somatic Cells – ( soma = body in Greek)

are all the cells is our bodies

those are the ones that will go through Mitosis and make our body grow, or skin regenerate, etc.

What cells go through Mitosis????

Multicellular Organisms have two types of cells:

b) Sex Cells or gametes: two types – egg and the sperm

•The sex cells are formed through Meiosis – a different type of cell division and they will not go through Mitosis

The Cell Cycle – is the series of events that take place in the cell, from one cell division to another(copy on handout)

Phases of the Cell Cycle – handout

1)Interphase – cell grows and organelles duplicate, Dna is copied and the chromosomes duplicate, cell grows more and prepares for cell division. The cells that will not divide anymore are always in Interphase.

2) Cell Division:a) Mitosis – 4 phases b) Cytokinesis – when cytoplasm divides creating 2 cells – it is different in plant and animal cells

Interphase : DNA in the nucleus that is usually in the form of chromatin will condense in chromosomes

What happens to chromosomes before cell division, during Interphase and after cell division???

Phases of Mitosis

Handout printed from the school website, page 162

ProphaseMetaphaseAnaphaseTelophase

Centriole is an organelle composed of protein microtubules. They appear, in pairs, close to the nucleus during cell division. The spindle fibers will form between the two centrioles and are attached to the centromere of a duplicated chromosome.

Spindle Fibers will pull the chromatids apart during cell division

Centrioles are present only in animal cells and some unicellular plant cells

•plant mitosis takes place perfectly with microtubules forming spindle fibers but without the help of centrioles.

CYTOKINESIS

Contractile ring pinches the membrane and the cell divides in the pinched area

A new membrane forms inside the cell

A B C

D E F

Lab

The results of Mitosis – read page 163

Karyotype – picture of all the chromosomes from an individual’s cells In this picture, the chromosomes are in pairs but are not duplicated as in page 163 of the handout

In each pair there are two homologous chromosomessimilar in length, gene

position, and centromere location

Types of Asexual Reproduction – organisms come from one parent

•Budding

•Binary Fission – reproduction in unicellular prokaryotic organisms

•Mitosis – reproduction in unicellular eukaryotic organisms

Budding in Yeast – page 164

Budding in Hydra – fresh water animals , few millimeters long

Binary Fission = Fission in Bacteria – page 164

Regeneration in Planarian – type of asexual reproduction – page 164

Regeneration in Starfish

Regeneration in Lizards

Skin and Liver Regeneration