DNA Questions
- DNA stands for deoxyribonucleic acid. This DNA is important because it contains the information for how proteins are made. The proteins, in turn, create the cells which are the most basic unit of life, according to the Cell Theory.
- There are living organisms on this planet that primarily use genetic material that is not DNA. RNA also contains genetic information that some archaea use as their main genetic material. Viruses can also be considered by some to be alive and they primarily use RNA as well.
- One important property of DNA is that it is shaped like a twisted ladder. This allows it to be split down the middle and helps with replication. DNA also is comprised of adenine, thymine, cytosine, and guanine, where each base only pairs with one other base. Adenine only pairs with thymine and cytosine only pairs with guanine, and they make up rungs of the ladder. When DNA is split down the middle, complementary bases can be added to the separate strands thus allowing for replication. Finally, DNA can be compacted enough to fit a large amount of information into a very small cell.
- The size of the DNA molecule does not determine the complexity of the organism itself. For example, the marbled lungfish has 40 times the number of base pairs in their genome than humans, but humans are more complex than marbled lungfish. This suggests that the genome size does not clearly indicate the complexity of the organism.
- The strands of DNA are made up of sugar groups, phosphate groups, and the four different nitrogen bases. These four nitrogen bases are adenine, thymine, guanine, and cytosine. All of these combined make up DNA.
- L.U.C.A. is the hypothesis that there was a first organism, a first cell, that all other cells came from. The answer from question five makes the L.U.C.A. hypothesis less likely. There are so many different combinations for DNA, and so there are many different types of genes. These genes can be lost or swapped, and so it makes it hard for us to know the genes that were in L.U.C.A. if there was even a single common ancestor at all.
Strawberry DNA Lab
The lab we did in class started with our groups putting strawberries in a Ziplock bag and mushing them up. We then proceeded to pour 20ml of a soapy/salty solution into the bag, and mix that together. Next, we pressed the solution through cheesecloth to strain out the chunks of strawberry and get just the solution into the vial. We then poured chilled ethanol into the vial, and a stringy, slippery substance rose from the strawberry solution, and it was the strawberries' DNA. It was interesting to see the DNA like that as we knew that DNA is shaped like a double helix, or twisted ladder, and the DNA we extracted did not look the same.
DNA is stored inside the nucleus in tightly wound strands called chromosomes. These strands sometimes come in groups, and this is called polyploidy. Inside our cells, our chromosomes are paired with each other for a total of 23 pairs of chromosomes, while strawberries' chromosomes are grouped in groups of three, called triploidy. Having larger groups of chromosomes means the DNA is easier to pull out.
- The processes we went through with the strawberry solution corresponded to extracting and isolating the DNA of the strawberries. The initial smashing and grinding of the strawberries served to break open the cells. The second step of mushing the strawberries with the salty/soapy solution served to break up the proteins and dissolve the cell. The third step of filtering the strawberry mush through the cheesecloth separated the components of the cell. The addition of the ethanol precipitated the DNA from the solution and that was the fourth and final step.
- The DNA as it came out of the strawberries appeared as a while, filmy, stringy substance. This is in contrast to how I know the chemical structure of DNA to be which is a double helix that looks similar to a twisted ladder. These two differing looks of DNA is attributed to the detain in which we observed the DNA. The substance that came out of the strawberries was lots of DNA and we couldn't see the finer details of DNA, where as if we had a very strong microscope we would be able to see the real structure of the DNA molecule.
- In the final step of our lab, we poured cold ethanol in the vial with the strawberry solution, and the DNA rose to the surface of the ethanol. This is because DNA is soluble in water and not soluble in ethanol. Solubility is the ability of a substance, a solute, to dissolve in another substance, a solvent. So DNA dissolves and creates a solution in water, but when we poured the ethanol in, DNA could not dissolve in it, so it began to float around and we were able to take it out of the vial.
- The analogy of a single cotton thread being like an individual strand of DNA and a rope made of thousands of strands of cotton like the large ball of DNA we extracted from the strawberries is a very suiting analogy. A single strand of DNA is very hard to see like a single strand of cotton, but when bound together like the cotton into a rope, we are able to see the DNA better. Although we can see the DNA, we still cannot see its true double helix structure just as in the rope you could not pick out a single strand of cotton and see its basic structure.
- It is important for scientists to be able to extract DNA because one, it allows for easier viewing of the DNA strands as opposed to trying to look at DNA when it is coiled up inside the nucleus of the cell, and two, this visible DNA can be used to study individual genes and find genetic diseases. Not only is DNA useful when it is extracted, it is also a neat thing to do at home. The DNA is most. Useful because the individual genomes can be studied to copy or to determine genetic diseases.
- In many types of food there is DNA, but not in all food. Organic food that comes from the ground has DNA in it because it was alive at some point. Before you eat an apple, it was once the fruit of an apple tree, and so it is made up of cells which contain inside genetic information to make that apple. But food that is not organic and doesn't come from the ground does not contain DNA. Hard candies that are made from sugar and synthetic colors and flavor were never alive and are not made up of cells so they do not have DNA.
DNA is stored inside the nucleus in tightly wound strands called chromosomes. These strands sometimes come in groups, and this is called polyploidy. Inside our cells, our chromosomes are paired with each other for a total of 23 pairs of chromosomes, while strawberries' chromosomes are grouped in groups of three, called triploidy. Having larger groups of chromosomes means the DNA is easier to pull out.