Quizlet Vocabulary Game, M7
Videos, etc. for M7
Whew! Talk about something over my head! Well, I
think I got it, thanks to Apologia's teachers being willing to email back and forth with answers to my questions. =)
Thank. you. Andrea! (I don't know who she is, but she has to be the most patient person ever!)
Last week we did
experiment 7.1, DNA Extraction.
What??? Extracting DNA!?! Yep.
But of course it was in clumps, or we'd never have been able to see anything.
In fact, it takes a powerful microscope to even be able to see the
chromosomes, which are long strands of DNA in the nucleus that are coiled up and compacted. S
ee image. (
source)
Let's see... how big is a chromosome?
Well,
two thousand average cells can fit in a line across your fingernail.
Breaking that down,
each cell of humans has 46 chromosomes.
One chromosome is made of a single strand of DNA, that when stretched out, is about 6 feet long!
And there are 46 of those in each cell!!! (um... 46 x 6 x 2,000 = mind boggled)
Ummm... evolution did not do this. God is our Creator, and he did not need to use evolution. =)
Experiment 7.1, DNA Extraction
--We put dried split peas in very cold salt water, and ran it thru my food processor. This was to expose the cells. Salty water will help the DNA solidify and appear in the alcohol later. We used cold water to help keep the DNA intact during the extraction process. (More about that in a minute.)
After running the food processor for several minutes, the peas still did not really grind up or anything, but the water did turn light green (but was not see-through). I wasn't sure if it should have been ground up more, but the experiment worked!
--Then we poured the pea liquid through a small strainer and added 2 Tbs. of clear, liquid hand soap, and stirred very slowly. (Supposed to work better than dish soap.)
But
why add soap? Well, what does soap do? It breaks down fats and grease. The plasma membrane of a cell and the nuclear membrane are made up of
phospholipids. Lipids are fats. The soap allows the cell and nucleus to open to expose the DNA. The cell's contents will now be mixed together.
We allowed it to sit awhile -- longer than the book recommended because we were going over some other stuff. Maybe 30 minutes!
--Then we added a little
meat tenderizer, again stirring slowly. The DNA strands are wound around proteins, and certain enzymes in meat tenderizer help break these down. When we used cold water, it was to keep the DNA intact from the enzymes that are
already present in the cytoplasm of the cell. The cold slows down the enzymatic reactions. (The purpose of enzymes being present in the cytoplasm is to destroy the DNA of viruses that may enter the cell.)
But at this step, we were now ready to break down the DNA proteins with enzymes, so we added the meat tenderizer.
--Then we finally added refrigerator-cold, rubbing alcohol. I found some 91% isopropyl alcohol. Yay! I'd read that a higher percentage would do better, and also that it would do better if the alcohol was cold.
We tilted the glass, and slowly poured the alcohol down the side (yes, the
inside, lol), so that it would not mix with the green pea mixture.
We had instant results! Clumps of DNA! =) These clumps also contain RNA.
After waiting maybe 20 or 30 minutes more, we checked the glass again and this is what we had.
See the thin strings near the bottom? Those are not
single strands of DNA. They are tangled strands of DNA.
I found a lot of this information on this page of
FAQ's, and of course some was in the biology textbook. Those FAQ's had said for better results to allow more time for each step, which we unintentionally did! =)
Here are
instructions (
PDF version) if any other blog readers need them, and an instructional
video. Neither are exactly like the textbook, but close.
I've found that if I look up the experiments we are going to do, I can find a tip here and there that might give me more insight as to the
why of some things, and also maybe help prevent common mistakes. (Yes, I am prone to those!)
We also learned about DNA and RNA (of which there is more than one kind). Two kinds are messenger RNA (mRNA) and transfer RNA (tRNA). We learned about transcription and translation, the processes by which DNA makes proteins.
We learned about mitosis (asexual reproduction of cells) and meiosis (sexual reproduction), and about diploid and haploid cells.
We learned a little about how a virus uses human (or animal) cells to reproduce the virus, since a virus cannot reproduce itself.
This was a very interesting and complex module. I've said this before, but I am
always amazed at God's awesome creation, and how intricate it all is! =)