As we move into our new unit on genetics, let's take a closer look at our own DNA and how that relates to what we know about cell theory.
Directions: Today you and your shoulder partner will be working together to extract samples of one person's DNA. In order to do this you and your partner need to first read the background and procedures.
First, copy these questions in your journal about the background, qualitative observations and self-reflection. Label the page DNA Phenomena Lab. You will answer these as you read and conduct the lab.
Questions:
What are the three parts of cell theory?
What type of cells do humans have and what do they contain?
What is DNA?
Write your qualitative data based on what you observe during the lab. Write notes during each step, and be sure to be descriptive.
Self-reflection: how can observing the phenomena of human DNA extraction help you remember the meaning of these terms above? Give two reasons using your observations.
Background:
Yesterday we learned cell theory. Cell theory tells us three important things about cells:1) All living things are made up of cells.2) A cell is the smallest unit in a living thing.3) All cells come from other cells.
Cells found within animals and plants (and you!) are called eukaryotic cells. Eukaryotic cells have a nucleus and organelles contained within the membrane. As we know from our last unit, the nucleus functions as the control center for the cell. Within each nucleus, chromosomes contain DNA. When DNA works correctly, it helps keep the body functioning properly. DNA helps cells to make the substances called proteins, which the cells need to live. DNA also allows living things to reproduce. The genes in DNA pass along physical traits from parents to offspring.
Materials:
paper cup
Gatorade
rubbing alcohol
pineapple juice
1 wood skewer
jar
Procedures:
When we are ready as a class, take the mouthful of sports drink and vigorously swish it around in your mouth like mouth wash. Keep going for at least 2 minutes. This takes some stamina — it’s harder than it sounds to swish for that long! It also helps if you scrape the insides of your cheeks a little with your teeth. No blood, please; we are after the DNA from your cheek cells, not your blood type!
Spit the sports drink and cheek cell solution into a small paper cup, then pour it into your jar until it is about one-third full.
Add liquid dish soap until your container is about half full. Put the lid on and mix the contents by rocking the container and turning it upside down several times. Be gentle, your goal is to mix the contents but to avoid causing bubbles from the soap.
Add a few drops of pineapple juice or meat tenderizer solution. Repeat the gentle mixing.
Gently add alcohol to the solution (Mr. Hodges will help with this part.)
Now it’s time to get that icy cold alcohol out of the freezer. Take the lid off of your cheek cell solution and tilt the container in one hand. I come to you and gently trickle a small amount of alcohol down the inside of the jar so that the alcohol forms a layer floating on top of the cell solution. Return the container to its upright position and set it aside for 1 minute.
After a minute, look carefully at the place where the alcohol makes a layer floating on top of the cheek cell solution. Write what you see. Gently put the skewer down into the container so that the tip touches this material. Carefully twirl the skewer in one direction only; if you are lucky the stuff will wind around the skewer so that you can lift it out through the alcohol layer to look more closely.
Behold your own DNA!
8. At the end of class, finish up your questions. Have one person dispose of the DNA jar contents in the the sink located on the left side of the counter up against the wall. Place all other materials in the center of your table. If necessary wash your hands.