Mitosis

1. Which stage does the following occur

Chromatin condenses into chromosomes	Prophase, The first mitotic stage in which the copied DNA and protein condense to grow mitotic spindle.
Chromosomes align in center of cell.	Metaphase, pressure is put on the spindle fibers which causes the chromosomes to align.
Longest part of the cell cycle.	Interphase, the DNA duplicates, the centrioles split, and proteins produce. Can last 12-24 hours.
Nuclear envelope breaks down.	Prometaphase, the nucleus is not visible anymore, spindle fibers go on top of each other in the cell center.
Cell is cleaved into two new daughter cells.	Cytokinesis, spindle fibers start degrading until only a small part is left. It is in this part that a ring is created and eventually cleaves the cell into two daughter cells.
Daughter chromosomes arrive at the poles.	Telophase

Watch the video carefully.

2. The colored chromosomes represent chromatids. There are two of each color because one is an exact duplicate of the other.

--How many chromosomes are visible at the beginning of mitosis? At the very beginning none, but towards the middle four.

-- How many are in each daughter cell at the end of mitosis? In the very end there are none, but in Cytokinesis there are three.

--The little green T shaped things on the cell are: Centrioles.

-- What happens to the centrioles during mitosis? They divide.

3 . Identify the stages of these cells:

This is metaphase because the chromosomes are all aligned.

This stage is Cytokinesis because the daughter cells are being cleaved.

This stage is Prophase because the mitotic spindles are forming.

Another Mitosis Animation

Go to www.johnkyrk.com/mitosis.html

View the animation and sketch the cell in:

Prophase The chromosomes are condensing to form long mitotic spindles.

Metaphase The spindle fibers are pressurized which causes the chromosomes to align in the center of the cell.

Telophase The chromosomes and spindle fibers are being pulled apart to opposite ends of the cell by protein. The chromosomes are being stretched out and turning very long and thin. Finally two nuclear envelopes envelope the stretched out chromosomes and the cell splits into two daughter cells.

Onion Root Tip - Online Activity

http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html

Read the introduction, then click the “next” button.

You will have 36 cells to classify. When you’re finished, record your data in the chart below.

	Interphase	Prophase	Metaphase	Anaphase	Telophase	Total
Number of cells	20	10	3	2	1	36
Percent of cells (calculate: number of cells divided by total cells x 100 )	55%	27%	8.3%	5%	2.7%	100 %

Mitosis in Whitefish & Onion Roots

http://www.biologycorner.com/flash/mitosis.html

For each organism, identify the stage of mitosis.

	View 1	View 2	View 3	View 4	View 5
Whitefish	Telephase	Metaphase	Prometaphase	Anaphase	N/A
Onion	Metaphase	Metaphase	Prophase	Interphase	Anaphase