Unit 5 Reflection

This unit was about DNA and what it does.  DNA contains the code for all life. It is made of a double helix that is connected by nucleotides. The nitrogen bases are purines (Adenine and Guanine), and pyrimidines (Thymine and Cytosine). Adenine (A) pairs up with thymine (T). Cytosine (C) and guanine (G) pair up.
DNA is unzipped by enzymes. DNA polymerase uses one of the strands as a template to add matching nucleotides to it. DNA codes for proteins. First, DNA is made into mRNA by RNA polymerase that matches spare nucleotides to make single stranded RNA. This is transcription. Second is translation. mRNA arrives at the ribosomes, which read codons to make amino acids which become proteins.
Sometimes there can be mutations. Point mutations change one or two bases. They can be substituted, inserted, or deleted. If the mutation occurs at the start then it is likely to be more harmful.
We also learned about gene regulation. The genes can be turned on or off based on when it needs to. It is extremely complex in human cells. In bacteria for lactose, a repressor molecule is attached to the operator to stop RNA polymerase from working. However, when lactose is present the repressor is detached and the gene for making lactase to break down lactose is created.
I found this unit to be relatively short and easy, however gene regulation is a little complicated and confusing. I tried using reading to learn by re writing key points on flashcards and quizzing myself. It worked quite well. I am a better student today because I understand more about previous unites, especially unit 4 and 3 which had to do with genetics and cells. I have a bunch of unanswered questions. Can we change someones DNA? How does the mRNA get to the ribosome? How do the ribosomes make the amino acids from the codons? What happens to the other DNA strand that does not take place in making mRNA?  Can we ever clone humans? \

A picture of extracted DNA 

DNA replication 

https://commons.wikimedia.org/wiki/File:0323_DNA_Replication.jpg

Protein synthesis conclusion

There are two major steps to make protein. First, transcription occurs. In this step, DNA is unzipped, and RNA matches the nucleotides to make a single stranded mRNA. Uracil replaces thymine. The mRNA leaves the nucleus for the cytoplasm. Second, translation occurs. The mRNA binds with a ribosome. The ribosome reads 3 bases (codons) at a time and determines with amino acid corresponds to that codon. The amino acids link together and eventually become a protein.

The mutation that causes the most harm is frameshift mutation. Substitution can be deadly, but rarely, because it only changes one amino acid and sometimes it may not change it at all. Where the mutation occurs is very important. If a deletion or insertion is made in the beginning, then all the codons in the DNA sequence after it will be moved forward or backwards. If the mutation happens towards the end, then only the codons after it will be affected. If the T we removed was near the end, then more codons would have been coded, and less would be affected. However, it was near the start, so many more codons were not coded.

The mutation I chose in step seven was a frameshift mutation, deletion, that took away the first codon.  This mutation affected the proteins the most out of all the mutations, because it took away the start codon, Met (AUG). None of the proteins were made because the ribosome(s) did not start to read them. It was really important that it was near the start. If it was near the middle, all codons would be read, but some would not necessarily be the right ones. If it was near the end, then all codons would be read, and a few would be the wrong ones.

A single mutation can greatly affect a person's life. Tay-Sachs disease is a rare inherited disorder that eventually destroys nerve cells in the brain and spinal cord. The most common form of Tay-Sachs disease is shown during infancy. Infants with this disorder usually appear normal until the age of 3 to 6 months, and their development slows and the muscles used for movement weaken. These infants lose necessary skills such as turning over, sitting, and crawling. They also experience intellectual disability and seizures. Children with this form of the disorder usually die during early childhood. 

Picture Links: 

http://www.bing.com/images/search?q=Baby+Boy+Crawling&view=detailv2&&id=28632541ED07699F5E9AF6849BE8531E657F9C69&selectedIndex=0&ccid=j9GcfQ24&simid=608050263347168714&thid=OIP.M8fd19c7d0db89dde16f628e748e24c18o0&ajaxhist=0

https://commons.wikimedia.org/wiki/File:Missense_Mutation_Example.jpg

DNA extraction

In this lab, we asked the question: How DNA be separated from cheek cells in order to study it? We found that DNA becomes visible during precipitation, when we gently poured alcohol into the Gatorade, it rises up from the Gatorade into the alcohol. First, we swished Gatorade in our mouth, after we gently scrapped the inside of our mouths, which was homogenization. Then, we spit it into the cup and added an enzyme (pineapple juice) and soap, which was lysis. Then precipitation occurred once we slowly poured cold alcohol into the Gatorade. Since DNA is polar and so is water, the DNA was dissolved in the water. Once it came in contact with the non polar alcohol, it was able to form into visible stringy clumps with oxygen. This supports our hypothesis, because we predicted the DNA would become visible during precipitation.

While our hypothesis was supported by our data, there could have been a few errors. First, the alcohol could have mixed with the Gatorade if you poured it too hard. That would cause the DNA to remain unseen because it would not rise to the top. Second, there could have been too much  Gatorade and/or too little cheek cells . That could have caused the DNA to not show up or not float up to the alcohol during precipitation. Due to these errors, in future experiments, I would recommend to have a measured amount of Gatorade and wipe the inside of the cheek with cotton around ten times. To solve the Gatorade and alcohol mixing, you should tilt the Gatorade test tube and let the alcohol trickle in.

This lab was done to demonstrate that DNA is found in all cells, and it is possible to make it visible during precipitation. From this lab I learnt that the protocol for DNA involves three steps: homogenization (where we added a protease and enzyme), lysis, and precipitation, which helps me understand the concept of DNA extraction that many scientists use. Based on my experience from this lab, I understand the basic methods scientists use to extract DNA, and a LOT or DNA is inside cells.