week of 12/8/08

Monday:

on Monday we read about cells in our books.  I learned that mitochondria can have DNA, DNA is in the nucleus of all living things, lipids make up the cell membrane, and cellulose sugars make up the cell wall

Tuesday:

On Tuesday we started our crime investigation.  our suspects are:

me

Stephen 

Ellen

Nick

Jordan

Brian

notes from witnesses about suspects:

• student seen leaving room in Friday when no teacher was in the room
• witnesses claim that individual had dirty blond hair, was somewhat tall, and weighed approximately 80-120 lbs
• it was not noticed whether the person was a male or female or whether they had long or short hair due to the fact that they had a "hoodie" on

we want to find out who stole Mr. Finley's moon rock!!

Wednesday:

on Wednesday we started DNA testing.  we started out by making our own lysis buffer- 1/5 teaspoon salt, 1 teaspoon baking soda, water, and dish soap.

first we put the lysis into the test tube

second the suspects all swabbed their cheeks TWICE and gently rubbed it into the test tube

third we added one drop of pineapple juice to the test tube

fourth we put a cork on top

fifth we prepared our alcohol by putting it in ice so it would be cold

sixth we added the cold alcohol to the test tube

Thursday:

on Thursday we first took a quiz on cells.  then we went online to learn about gel electrophoresis  we filled out a worksheet about electrophoresis too.  electrophoresis is a process that sorts DNA by its size.  the longest DNA strands are pushed to the bottom, and the shortest ones stay on top.  

to do an electrophoresis, you first make the gel, then you set up the gel apparatus, then you load the DNA sample into the gel, then you hook up the electrical current and run the gel, and lastly you stain the gel and analyze the results

we also read an article on the website called "Can DNA demand a verdict?"  this article talked about DNA being used in crime investigations.  DNA can be used as evidence to prove someone guilty or innocent.  but sometimes when doing the DNA testing, you can mess up and the DNA results can come out wrong.  so sometimes it is good to use DNA for evidence, but sometimes you mess up the tests and can accuse someone or put someone in jail who is innocent, just because you messed up the test.

Friday:

on Friday we went over the sheet on electrophoresis and talked about more about DNA.  we also discussed the "can DNA demand a verdict?" article.  some main things we talked about were how everyone's DNA is 99.9% the same, and only 0.1% is unique.  we also talked about how identical twins have the exact same DNA.  Mr. Finley also told us about a t.v. show where a guy had a blood transfusion so when they tested his DNA, it came out as the person's who's blod was put inside him.  so technically you can change your DNA by getting a blood transfusion, because your DNA would come out differently

I thought these things were really interesting because i thought that everyone's DNA was different, but really everyone's DNA is pretty similar, and identical twins even have the exact same DNA,which i didn't think was possible

this week in science was pretty interesting, and i like learning about DNA.  can't wait till next week!

~*Mary*~