Stem Cells Webquest

Go to the NIH site on stem cells: http://stemcells.nih.gov/index.asp and click on the Info Center link “Stem Cell Basics.”  Starting with the “Introduction” section, read the information presented.

Use the site’s glossary to find definitions for these important terms:

Cell-based therapies: Treatment in which stem cells are induced to differentiate into the specific cell type required to repair damaged or destroyed cells or tissues.

Differentiation: The process whereby an unspecialized embryonic cell acquires the features of a specialized cell such as a heart, liver, or muscle cell. Differentiation is controlled by the interaction of a cell's genes with the physical and chemical conditions outside the cell, usually through signaling pathways involving proteins embedded in the cell surface.

Embryonic stem cell line: Embryonic stem cells, which have been cultured under in vitro conditions that allow proliferation without differentiation for months to years.

Proliferation: Expansion of the number of cells by the continuous division of single cells into two identical daughter cells.

Plasticity: the capacity for continuous alteration of the neural pathways andsynapses of the living brain and nervous system in response to experience or injury that involves the formation of new pathways and synapses and the elimination or modification of existing ones

Pluripotent: The state of a single cell that is capable of differentiating into all tissues of an organism, but not alone capable of sustaining full organismal development.

Answer the following questions:

1.   What are the unique properties of all stem cells?  Explain in your own words what each property means.

a.   All stem cells have three general properties:

                                              i.     they are capable of dividing and renewing themselves for long periods

1.   stem cells are able to replicate themselves numerous times

                                             ii.     they are unspecialized

1.   a stem cell does not have any tissue-specific structures that allow it to perform specialized functions

                                           iii.     they can give rise to specialized cell types

1.   come from unspecialized cells the process is called differentiation. While differentiating, the cell usually goes through several stages, becoming more specialized at each step. The internal signals are controlled by a cell’s gene which are interspersed across long strands of DNA, and carry coded instructions for all cellular structures and functions. The external signals for cell differentiation include chemicals secreted by other cells, physical contact with neighboring cells, and certain molecules in the microenviroment.The interaction of signals during differentiation causes the cell's DNA to acquire epigentic  marks that restrict DNA expression in the cell and can be passed on through cell division.

2.   What are the two main kinds of stem cells used by researchers?  What are the major differences between the two types in terms of their sources and usefulness to researchers?  Give examples for each type of stem cell.

a.   embryonic stem cells and non-embryonic "somatic" or "adult" stem cells. 

b.   differences

                                              i.     their different abilities in the number and type of differentiated cell types they can become.

1.   embryonic stem cells can become all cell types of the body 

2.   "adult" stem cells are thought to be limited to differentiating into different cell types of their tissue of origin.

                                             ii.     embryonic stem cells can be grown relatively easily in culture

                                           iii.     Adult stem cells are rare in mature tissues, so isolating these cells from an adult tissue is challenging

                                           iv.     tissues derived from embryonic and adult stem cells may differ in the likelihood of being rejected after transplantation

3.   List some of the diseases that scientists think may be treated using stem cell research and suggest how stem cells might be used to treat each disease.

a.   Type 1 Diabetes

                                              i.     it may be possible to direct the differentiation of human embryonic stem cells in cell culture to form insulin-producing cells that eventually could be used in transplantation therapy for persons with diabetes.

b.   Heart Disease

                                              i.     generate healthy heart muscle cells in the laboratory and then transplant those cells into patients with chronic heart disease. 

4.   What are the necessary characteristics that laboratory-manipulated stem cells will need to have in order to be successfully used in cell-based therapies.

a.   To realize the promise of novel cell-based therapies for such pervasive and debilitating diseases, scientists must be able to manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation, and engraftment. The following is a list of steps in successful cell-based treatments that scientists will have to learn to control to bring such treatments to the clinic. To be useful for transplant purposes, stem cells must be reproducibly made to:

                                              i.      Proliferate extensively and generate sufficient quantities of tissue.

                                             ii.      Differentiate into the desired cell type(s).

                                           iii.     Survive in the recipient after transplant.

Onion Root Lab

For the past two days we have been working on cells, mitosis, and onion roots! My last post was on a web quest of cells in the stages of mitosis. If you don't know the stages they are:

Interphase: The cell cycle stage between nuclear divisions, when chromosomes are extended and functionally active. The metabolically active non-dividing stage of the cell cycle.

Prophase: The early stage of nuclear division during which chromosomes condense and become visible. The initial stage of mitosis or meiosis in which chromosomes become visible and the spindle apparatus forms.

Metaphase:The stage of mitosis or meiosis in which spindle fibers are attached to kinetochores and the chromosomes are positioned in the equatorial plane of the cell. An intermediate stage of nuclear division when chromosomes align along the equatorial plane of the cell spindle.

Anaphase: The stage of meiosis and mitosis in which sister chromatids (meiosisII) or homologous chromosomes (mitosis and meiosisI) are separated by spindle fibers. An intermediate stage of nuclear division during which chromosomes or chromatids are pulled to the poles of the spindle.

Telophase: The terminal stage of mitosis or meiosis in which chromosomes uncoil; the spindle breaks down; and cytokinesis usually occurs. The late stage of nucleirdivision when daughter 

nuclei re-form.

If you want to know more or find more definitions the site below is where I obtained my information.

http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-I/interphase.html

This post is about the Onion root lab that my group and I worked on!

We had to take onion root tips and place them under a microscope. We needed to find and count the ones in Interphase. Then find and count the ones in Prophase and so on. Then once we counted all the cells we added them up and it gave us our total cells we counted. Once we did that we had to divide the number of cells by the total to get the percentage. 

Below is a table we created to help us keep track of our data:

Allium Onion Root Tip	Interphase	Prophase	Metaphase	Anaphase	Telophase	Total
Number of Cells	39	21	9	8	6	83
% of Cells	47%	25%	11%	10%	7%	100%

For our first run we use and Allium Onion root tip. We had 39 cell in interphase, 21 cells in prophase, 9 in metaphase, 8 in anaphase and 6 in telophase. Our total added up to 83 cells. We then divided the number of cells by the total and got the percentages. While my group and I were  calculating the percentages, we noticed that the number of cells seemed to decrease as the stages went along, same with percentages. Anyway our next run was on a different cell. Below is our next run.

Mitosis in Onion Root Tip (Is Quadrple Stain)
	Interphase	Prophase	Metaphase	Anaphase	Telophase	Total
Number of Cells	63	34	25	15	13	150
% of Cells	42%	23%	17%	10%	8%	100%

For this table we worked with Mitosis in Onion root tips. The Quadrple Stain. We did the same to this table as the first table. Except we had a different total. Our total was 150 cells. In this cell we counted a lot more than the other one, so our total and percentages were a lot higher too. We found that no matter what cell during the stages of mitosis the number of cells in each stage will always decrease, hmm...interesting. 

After our group was done collecting data, it was time to make graphs!

Our graphs are on the percentages of the cells in each stage. Our first graph is from our first table.

This was our first graph. Like I said before you can see the percentage decrease with each stage. 

If you can't read the labels on the side heres what it says:
Interphase
Prophase
Metaphase
Anaphase
Telophase

Most of the cells stay in interphase and prophase for awhile. There are about (guesstimating here) 12 to 5 cells in metaphase and anaphase. About 5 to 3 cells are in telophase. Our next pie chart show the data from our second table

This is the pie chart for the Quadrple Stain data. The labels on the side say the same as the ones on the first pie chart. The colors are the same to. The only thing that is different is the percentages. this one had more cells than the last pie chart, but the stages still decrease in cells as they move along.

Onion Root Tips and The Cell-Cycle Webquest

At the beginning of this new semester in biology we have started to learn about Mitosis. To give us a general idea on how to identify the different phase of a cell dividing.

In this activity, you will calculate the lengths of the various phases of the cell cycle in an onion root tip. First you will view some slides and graphics of onion root tips provided by the Molecular Expressions Photo Gallery. Then you will complete the online activity provided by the Biology Project at the University of Arizona.

Part 1.

Use your browser to go to Molecular Expressions Photo Gallery: Mitosis

http://www.microscopy.fsu.edu/micro/gallery/mitosis/mitosis.html

Notice in the micrograph at the top of the page that there are cells in a variety of stages. View the onion slides in this section, then click on "mitosis" in the sentence "Learn the steps in mitosis ... " This will take you to a Java tutorial.  Keep in mind what you have learned here as you proceed to the second part of the activity.

Part 2.

Use your browser to go to Online Onion Root Tips at

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

Begin by reading the description of the five major cell phases. You will need to keep this information in mind during the activity.

Make a copy of the data sheet that appears on the second page. You will need it to answer the questions.

Proceed through the activity, identifying the phase for each cell you are shown. Pay attention to the hints if you misidentify a cell at first.

When you have completed the activity, answer the following questions:

1. What percent of cells were in interphase?

            A: 55%

2. What percent were in mitosis?

            A: 13%

3. Which phase of mitosis takes the longest?

            A: Interphase

4. During which stage is the nucleolus visible as a dark spot?

A: Interphase is when a dark spot is visible in the nucleolus

5. How can you recognize a cell in metaphase?

            A: When the sister chromosomes bond and are lined up

	Interphase	Prophase	Metaphase	Anaphase	Telophase	Total
Number of Cells	20	10	3	2	1	36
Percent of Cells	55%	27%	8%	5%	2%	100%

 After my partner and I were done working on categorizing cells we had to count them up and place the number in each category. For Interphase we had 20 cells, Prophase we had 10 cells, Metaphase we had 3 cells, Anaphase we had 2 cells and finally for Telophase we had one cell. The percentages below the numbers we got from dividing the number of cells by the total. The one with the highest percentage was Interphase with 55% and the lowest was Telophase with 2%.