Post on 17-Jun-2018
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
constant division that cells undergo is known as the cell cycle.
● Three main stages: ◦ Interphase◦ Mitosis (4 Phases)◦ 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 (Starts with 46 and ends with 92 Chromosomes), and prepares to divide into two similar cells.
● DNA is spread out (simplified) as chromatin
Stage 2: Mitosis
● Mitosis = The cell’s nucleus divides into 2 separate new nuclei, each with 46 chromosomes or 23 homologous pairs.
● 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 also known as sister chromatids.
◦ 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:
https://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
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