Miss HC 03/16/11

Minerals in Bone

A. Purpose:

Bones are incredible.  They are as strong as steel, yet light as aluminum.  Bone is actually made of chemicals that are extremely weak, but mixed together they create a structure that is extremely strong.  The purpose of this experiment is to learn what makes bones so strong, and how flexible they would be without it.

Bones are strong both because of the material they are made of and because of the structure of the bone.  Most bones are made of cells surrounded by a substance called the bone matrix.  The bone matrix is mostly made of collagen and minerals.  Collagen is a flexible, threadlike protein made up of three strands, and it helps to make the bone flexible.  The minerals in bones are principally made up of calcium, and they are rigid and hard, making the bones strong.

The human bone structure is extraordinary as well.  Around your medullary cavity, there are two types of bone: compact bone and spongy bone.  In the compact bone structure, the collagen and minerals are packed together very tightly to form a tough structure that is very sturdy and can withstand shocks.  Spongy bone, on the other hand, leaves open spaces in the bone network.  Spongy bone also contains bone marrow, which produces many cells in your blood.  In the bone tissue are living bone cells, osteoblast, which are constantly creating more spongy and compact bone tissue.  There are also other bone cells, osteoclast, which break down the old bone tissue so the new bone can replace it. 

Both collagen and minerals need to be present to form these types of bone.  The collagen and minerals also have to be present in the right amounts to create a bone that is flexible enough to bend under stress but strong enough to support the body.  The body naturally blends the materials to create bone. In addition, the body produces bone on a regular basis.  This experiment hopes to show what a bone is made of and which substances help to make them so amazing.

Since bones have such unique properties, it is extremely important for scientists to understand what they are made up of and why these substances make them this way.  In fact, if scientists can understand how the bones are made, and if they can recreate the bone's making, then this knowledge could be very useful.  Applied scientists have already attempted to create "artificial" bone tissue, but they have not succeeded in producing any material that is both as strong and light as bone.  This topic is of interest to science because full understanding of a bone's structure, and the ability to duplicate this material, could be extremely helpful to many fields of study.

Hypothesis: If all the minerals in a bone are dissolved and only collagen is left, then the bone will be very flexible.

B. Equipment:

1. An uncooked chicken bone (preferably a wishbone or a wing)
2. A jar with a lid
3. Vinegar (preferably white)

C. Procedures:

1.  Clean the bone of all meat and tendons.  Make it as bare as possible.
2.  Allow the bone to dry overnight.
3.  The next day, test the bone by trying to gently bend it.  Do not use so much force that it breaks!  Notice that the bone bends a bit but it is still mostly rigid.
4.  Fill the jar with enough vinegar so that the bone will be fully immersed.
5.  Drop the bone in the jar and close the lid.
6.  Every day, pull the bone out of the jar and test it like in step 3.
7.  Note the difference you observe.
8.  Put the bone back in the vinegar and close the jar again.
9.  Continue this process for seven days or more.
10.  Once the seven days are over, pour the vinegar mixture down the drain, throw the bone away, and clean up your mess.

D. Observations:

1.  The bone was slightly pink in color, and extremely moist and slippery.  It was about four and a half inches long, and perhaps three-fourths of an inch thick.  Due to the fact that the tendons were firmly attached, it could not be scraped completely bare; however, it was cleaned as much as possible.
2.  After it was dried, the bone appeared slightly darker.  It was very rigid and did not bend very much.
3.  The jar was five inches tall, and the chicken bone fit diagonally in it with about half an inch at the top.  Vinegar was poured in till it covered the top of the bone.  The vinegar was clear and smelled sour.  The lid was screwed on firmly.
4.  When the bone was removed from the vinegar jar on the first day, it was still quite hard and did not bend.  Most of the remaining tendons had come off and were floating around in the jar.  The vinegar was very cloudy looking.
5.  On the second day, the bone seemed to be unchanged.  However, the vinegar had cleared up, and although it was still cloudy, the tendons seemed to have settled to the bottom of the jar.  There was a dark brown substance at the bottom of the liquid and there were small oil spots floating at the top of the jar.
6.  On the third day, the bone was able to be bent slightly at the tips.
7.  On the fourth day, the bone was extremely flexible at both ends, but the very middle of the bone was still quite rigid. The bone was whitening in color, and it was very slippery at the ends.
8.  On the fifth day the bone was more bendable, and the end could be twisted halfway around.  The middle of the bone was supple as well.
9.  On the sixth day the bone did not seem to be more or less flexible, but it could be stretched.  The bone felt slimy at the touch.
10.  On the seventh day, the bone was both stretchy and flexible, much more so than before it was immersed in vinegar.

E. Conclusions:

This experiment showed that a bone is made up of both collagen and minerals.  This was displayed by the fact that when when the minerals were dissolved, the bone was made flexible because of the collagen in it.  If bones are made out of both collagen and minerals, and bones are more flexible and less strong with less minerals, then it can be concluded that the minerals help to make the bones strong.  Since chicken bones are mostly made up of collagen and minerals, like human bones, the experiment gave a good demonstration of what makes human bones the way they are.

Even though the experiment went well overall, there are plenty of ways it could be improved.  For example, although every effort was made to scrape the bone clean of tendons and meat, there were still some tendons that could not be taken off.  If there was a way to strip the bone of all tendons, that would be extremely helpful.  Another experimental variable was the amount of vinegar.  Every time the bone was taken out, a little of the vinegar came out with it, so the amount of vinegar in the jar was altered slightly from the beginning to the end of the experiment.  Although this probably did not affect the experiment too greatly, it was still something that had to be taken into consideration.

This experiment provided many new ideas for further research.  If the vinegar was changed every day, it could have a more striking effect on the chicken bone.  It would be interesting to test the used vinegar against new vinegar, and see what the chemical differences are.  It might also be intriguing to learn what exactly vinegar does to the minerals in the bone, and whether the collagen is affected at all by it.  Since there are many different sizes and shapes of bone, the types of chicken bone could also be changed.  The experiment could be performed for a longer period of time, to see whether the vinegar can continue to dissolve the minerals in the bone.  Because scientists are trying to create artificial bone tissue, it might be wondered whether they have made progress, and what they would use it for if they were able to recreate it.                                                            

F. Bibliography:

Domain:  http://www.pediatric-orthopedics.com/
Document:  Topics/Bones/bones.html

Rosenoff, Steven. Class Lecture. February 28, 2011.

Wile, Dr Jay L. Exploring Creation With General Science. Apologia Educational Ministries, Inc. 2003.