Transcript Cell Division - Cobb Learning

How Cells Make More Cells
The CELL CYCLE is the process
by which cells divide to make new
cells.
• There are three main stages to this
cycle. They are:
1. Interphase
2. Mitosis (prophase, metaphase,
anaphase, and telophase)
3. Cytokinesis
I. Interphase
• This part takes the longest amount of time
of all of the stages of cell division.
• Here’s what’s going on:
• The cell grows- doubles in size, organelles
get bigger or more of them are produced.
• The cell copies it’s DNA-This is called
REPLICATION. Now there’re two sets.
• The cell prepares to divide- some
structures needed for division are made.
II. Mitosis
•
Mitosis is when the cell’s nucleus
actually divides and each new cell (called
daughter cells) gets a copy of the DNA.
1. Prophase: chromosomes (rod-shaped)
form from chromatin, nuclear
membrane breaks down, spindle fibers
form.
2. Metaphase:
• Chromosomes line up across the middle
of the cell.
• Spindle fibers attach to the
chromosomes at the centromere (a
structure that holds the chromatids
together).
3. Anaphase
• The centromeres split.
• The two chromatids move toward
opposite ends of the cell.
• The cell begins to stretch out.
4. Telophase
• Chromosomes start losing their rod-like
shape and begin looking like chromatin
again.
• The nuclear membrane begins to reform
around the chromosomes.
III. Cytokinesis
• This is the stage in which the cell
completes the formation of two new
daughter cells.
• Animal Cells: New organelles are
distributed. Cell membrane pinches
around the middle into forming two new
cells.
• Plant Cells: This is a little different
because plant cells have a cell wall.
• A cell plate forms between the two
daughter cells and this forms a new cell
membrane.
• New cell walls form around the cell
membranes.
Timeframe for the cell cycle in a
human liver cell
I. Interphase: 21
hours
– Growth: 9 hours
– DNA Replication: 10
hours
– Preparation for
Division: 2 hours
II. Mitosis
– Prophase
– Metaphase
– Anaphase
– Telophase
III. Cytokinesis
1 hour TOTAL
What Does this Look Like?
• http://www.cellsalive.com/mitosis.htm