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I am looking for instructions or ideas on how to construct models of plant and animals cells for science project.  We can use any form of materials.  Example clay, styrofoam, paint, etc.  Needs to be colorful. Appreciate any ideas or suggestions.

Dear Joshua,
It sounds like your instructions are very complete. Only imagination and creativity are left up to you. I have seen these models in our local school, and they are quite varied. Some kids used different kinds of hard candy to depict the cell components. Others used different shapes of styrofoam.  All of them seemed to make models of cells cut in half with the organelles sticking up into space.
What hobbies do you have?  Would one of those suggest fun materials for you?  Could you use plumbing materials?  How about different kinds of rocks you find around your neighborhood?  What about sporting goods?  How about a collage out of magazine photos?  The picture of a winding road could be cut into an oval shape and be used as a mitochondrion, for instance. Getting the right scale would be the hard part.
Use your imagination and consider it a challenge or puzzle.

Dr. Pat

I'm doing a project on DNA and I was wondering if you could tell me what the highest percentage of the same DNA someone could have?  I also want to know what percentage you have of your grandparents' genes and your sibbling's genes and your parents' genes.

Hi Amanda,
Lets put your questions in order of increasing difficulty.

1) What is highest percentage of the same DNA could you and someone else have?
2) What percentage of your genes did you get from your parents?
3) What percentage of your genes did you get from your grandparents?
4) What percentage of your genes do your siblings also have?

The answer to # 1 is: What percentage of the same DNA would you and your identical twin have? (100%)

The answer to # 2 is: You get one half of your DNA from your mother and one half from your father. Thus, one half of your genes came from your mother and one half from your father. (50%)

The answer to # 3 is: Your mother got half of her genes from her mother and half of her genes from her father. She only gave you half of her genes. (If your mother and father both gave you all their genes, you would have twice as many genes as each of them. Then your children would have 4 times as many genes as your parents, until the cells could not fit all that DNA. So, nature said, "Hey, lets have mothers only give half of their genes and fathers only give half of theirs. That way all people will have the same total amount of DNA!") So, half of your genes are from your mother and half of that is from your mother's mother. That translates into one half of one half, or one fourth of your genes came from your mother's mother. (25%)

The answer to #4 is: Your mother and father each give you half of their genes. It is random which half you got. You could have a sister who gets exactly the same genes from each parent and she would be identical to you. Or you could have a brother who gets all the genes you do not. So the answer is more complex than the other answers. (The correct answer to #4 is anywhere from 100% down to 0%.)

Thanks for asking,
Dr. Pat

I e-mailed you before and was wondering if you could answer a few more questions for me....
1) When was the first discovery of DNA?
2) How did scientists know for a fact that you get 25% from each parent... What did they have to do to find that out?
3) If someone said clone this person... Do we have the right tools and enough technology for that to be possible?  And, if not, how long until scientists can do that?
4) Is it true that likes and dislikes have been passed down through genes?  An example would be if a Mom really enjoys doing something or eating something or has some little habit, could that be passed down?
5) What other than testing to see if a baby is your biological baby, is DNA testing used for?
6) How much DNA is in your body?
7) Does anything else have DNA besides Mammals?  Like, do plants?

Well, that's all the questions I can think of today !  Thank you for your help !!!
Thanks,  Amanda

Hi again Amanda,
More great questions. You could be an excellent scientist. I will do my best to answer them.

1)  DNA was first discovered in 1869 by a Swiss biochemist named Friedrich Miescher. It was not until the 1940's that the DNA was proven to be the genetic material.

2)  You get 50% of your DNA from each parent and 25% of your DNA from each grandparent. It took a long time and many scientists to prove all of this. But the first to suggest that genes were passed on from one generation to the next was the Austrian monk Gregor Mendel. He was in charge of the monestary's garden. He made records of the traits of his pea plants that were passed on by the peas. He found this same 50/50 chance of the next generation having the color or size, etc. of the mother or father plant. More and more data like this had to be collected by many scientists before these numbers were accepted. They also needed to connect the heredity material to DNA, which did not happen for a long time.

3)  We probably have almost all the theory to do it, but need time and experience to put together the exact details. How long it takes will depend upon how many scientists refuse to do such a thing because of their view of the ethics of it. What would you do?

4)  This is an unsolved question left for future scientists to determine exactly. Many people have an opinion, but little hard proof on the inheritability of 'personality' traits. Much of the work has been done by studying twins, who have exactly the same DNA, but whose personal likes and dislikes can be quite different. This whole area of debate is called: "nature vs. nurture"; meaning is it from your genes or from how you were raised.

5)  Right now heritage can be extended back many generations.  For instance, scientists have just recently shown that Sally Hemmings' decedents are also related to Thomas Jefferson.  DNA can also be used to show that a specific person is likely to have left evidence at a crime scene. DNA is used by paleontologists to determine how related different types of extinct animals were to each other, and what kinds of food they had in their bellies when they died.  DNA testing can determine if a person carries a gene for a genetic disease that they either might come down with or that they might pass down to their kids.  I am probably missing some current uses, and scientists are always inventing more.

6)  There is about 1% of a cell's weight that is from DNA. It is a rough number, but about 1% of your body weight is DNA.

7)  All living things have DNA. Plants, bacteria, animals.

Hope these answers help. Remember, the only stupid question is the one unasked.
Dr. Pat

I just want to thank you! you helped a lot!
Thank again!   Amanda


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