Cell Division (Mitosis) How does mitosis ensure that a new cell is identical to its parent cell?

The Cell Cycle● The regular sequence of growth and

division that cells undergo is known as the cell cycle.!

● Three main stages: !◦ Interphase!◦ Mitosis!◦ Cytokinesis

Stage 1: Interphase● During the first part of the cell cycle

known as interphase, the cell grows to mature size, makes a copy of its DNA, and prepares to divide into two cells.!

● DNA is spread out as chromatin

Stage 2: Mitosis

● Mitosis = the cell’s nucleus divides into 2 separate new nuclei.!

● One copy of DNA is distributed into 2 daughter cells.

Stage 2: Mitosis (Prophase)

● “Pro” means “first”: It is the first part of mitosis!

● What happens?!◦ DNA scrunches up into ! chromosomes!!◦ Nucleus dissolves

Stage 2: Mitosis (Metaphase)

● Chromosomes line up in the MIDDLE of the cell!

● Remember: !!Metaphase = Middle

Stage 2: Mitosis (Anaphase)

● Chromosomes are pulled to opposite ends of the cell by the centrioles with ropes called spindle fibers.!

● Remember: !!Anaphase = Apart

Stage 2: Mitosis (Telophase)

● The cell starts to form two new nuclei around the chromosomes!

● Chromosomes start to unwind back into chromatin!

● Remember:!◦ Telophase = Two Nuclei

Stage 3: Cytokinesis● Cytoplasm divides, distributing organelles into each of

the two new cells.!● Each new daughter cell has the same number of

chromosomes as the original parent cell.!● Remember:!● Cytokinesis = Cytoplasm splits

Cytokinesis in Animal Cells● In animal cells the cell membrane

pinches in creating two new cells, (each with ½ the organelles.)

Cytokinesis in Plant Cells● Form a cell plate across middle that

eventually turns into a new cell membrane, (new cell wall follows.)

Lets see all of mitosis together:

Length of the Cell Cycle● Cells spend most of their time during the interphase

stage of the cell cycle.!● Mitosis only happens at the end to make new cells

http://www.youtube.com/watch?v=m73i1Zk8EA0

Cell Cycle

includes

is divided into

http://www.youtube.com/watch?v=I5uFuvkN97I

Cell Cycle

includes

is divided into

http://www.youtube.com/watch?v=I5uFuvkN97I

Interphase Mitosis Cytokinesis

Prophase Metaphase Anaphase Telophase