DNA Extraction Lab

January 15, 2006 at 5:13 am #3212

Participant

Hey guys-
I’m a freshman and I take honors biology. I’m told that this class is equivalent to junior/senior classes at other high schools. I had three labs this week and a question sheet for each of them. On top of that I have another worksheet with a bunch of impossible questions to answer! One of the labs we did this week had to do with DNA Extraction. We mixed shampoo, salt, water, and a banana/distilled water solution. We mixed that for about 5 minutes to get rid of the foam. After that we put it all into two test tubes. We put them both in a centrifuge for 5 minutes. Then we had to get rid of the foam at the top. After that we had to pour out the supernate (clear top part of the test tube) into a chilled test tube. Then we added alcohol and let it sit for about 2 minutes. Then we could see the DNA (of the banana I’m guessing). Now I have lab questions about this and I have no idea how to answer most of them! I only got a few of them answered. Here are the ones I can’t figure out:

Why does the isolated DNA appear to be stringy?
If you extracted DNA from your cells, would you expect to see a difference in the results? Why or why not? I’m guessing yes…but I have no clue why!
Explain how the shampoo, salt, and alcohol function to isolate the DNA.
What is the purpose of the centrifuge?
What step was done to the DNA so that it could be visible?
How would you revise the procedure to extract DNA from other organisms? What other cell structure(s) might need to be broken or removed to free the DNA?
Describe in detail three ways in which a scientist could use the extracted DNA.
Give the name of a laboratory that would extract and use DNA in your community. (I live in Omaha, Nebraska…there’s nothing here! lol I have no clue!)

Oh and just so you know…I’m totally not just asking cuz I’m lazy! It actually took a long time for me to type all that! lol I’m really confused and I have a horrible teacher! If any of you have a clue about any of those I would be really grateful!!!!!!!
Thanks for your time!
-Jamie

January 15, 2006 at 7:28 pm #37294

MrMistery

Participant

Ok, i have never done such a lab cause there is no place in my country where i am allowed to work with such instruments, but i can try to help you solve your problems.PS: don’t take my answers for granted, i am not sure they are correct

quote :

Why does the isolated DNA appear to be stringy?
If you extracted DNA from your cells, would you expect to see a difference in the results? Why or why not? I’m guessing yes…but I have no clue why!

I would say no. Dna is DNA, no matter where it came from. the only difference between 2 organisms would be the length. It appears stringy, because it basically is. Look up a picture in your textbook of DNA.

quote :

What is the purpose of the centrifuge?

In any experiment, the purpose of the centrifuge is to arrange substances by their molecular weight. The "heaviest" stuff is at the bottom

quote :

How would you revise the procedure to extract DNA from other organisms? What other cell structure(s) might need to be broken or removed to free the DNA?

well, in order to free DNA from an eukaryotic cell you would need to distroy both the cellular membrane and the nuclear envelope. How you would do this i do not know.

I realise it’s not much, but it was all i can think of

January 15, 2006 at 8:07 pm #37302

thelovepirate

Participant

thanks!
oh and btw-my cousin is from romania! whats it like there?

January 15, 2006 at 8:09 pm #37304

MrMistery

Participant

because i can not use obscene language here, let’s just say it is not that nice. What city is your cousin from?

February 3, 2006 at 1:46 am #39395

yankees26

Participant

I am also a freshman taking honors biology (general freshman course if earth science) and my class just did that experiment except with onions (except we only have one lab a week, a double period of biology) and I;m writing my lab report right now AND my name is also Jamie.

The shampoo breaks down dissolves the lipids and proteins in the cell membrane, hence breaking it down.

The salt covers up the negative phosphate ends which allows the DNA to come closer to each other. Otherwise the negative ends would repel each other.

Since DNA isnt soluble in alcohol, it is added so the rest of the mixture stays in the solution but DNA accumulates outside the alcohol layer.

February 3, 2006 at 6:11 am #39408

monotreme101

Participant

That teacher sounds crazy-hard, but it sounds fun at the same time!! (at least to me)

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