BIOLOGY
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This week you need to watch the brief video on thermophilic organisms below and then do some other stuff (described after the video): Youtube http://www.youtube.com/watch?v=g80bqHnR08Y
Research the thermophilic prokaryotic organism Thermus aquaticus, the polymerase chain reaction (PCR), and the role of Thermus aquaticus in PCR.
(1) What does DNA polymerase do in our cells (really, in all cells)?
(2) Describe the steps of PCR. What does the DNA polymerase enzyme of this organism (called “Taq polymerase” by scientists) do in the PCR?
(3) What is it about Taq polymerase that has made it useful in PCR? Your answer should focus on why the PCR process works better with heat-tolerant DNA polymerase.
(4) How has PCR revolutionized the field of crime scene forensics?
Your main response should be at least 150 words and include references to all information sources used. Two substantial response posts are also needed. As part of one of your replies search for and share a video, tutorial or web site that helps you and your classmates’ better understand enzymes, especially the DNA polymerase enzyme.
A. Proteins are the most structurally and functionally diverse class of biological molecules. Explain the basis for this diversity
B. Factors Affecting Enzymes (Watch Video and Comment)
C. Here is another camouflage story that of a real fish – enjoy! (Watch video and Comment
Respond to the postings below:
1. DNA Polymerase is an enzyme that is essential to DNA replication. It creates two new strands of DNA so that when a cell divides, there is a copy of the DNA in each of the two daughter cells. Polymerase Chain Reaction (PCR) has three main steps. In the first step, the temperature is raised so the hydrogen bonds break, then the two strands of DNA can be separated. In the seconds step, the temperature is brought down so that a primer can bond to each strand of DNA, and in the last step new strands of DNA are made using the original strands as templates, and DNA Polymerase Enzymes join with free nucleotides. Taq Polymerase works well for PCR because it is extracted from the thermos aquaticus which can withstand the high temperatures needed to preform PCR. In crime scene investigations, DNA samples are limited. PCR can duplicate existing DNA so that there is a bigger sample size.
2. DNA polymerases assist in cell reproduction by “assembling nucleotides” to duplicate DNA molecules for transmission from parent to daughter cell, thereby preserving the genome from one generation to the next (Mandal, 2019). Helicase unpacks the DNA for assessment, then polymerase identifies the structure of the DNA to be replicated, and the primase enzyme provides the “pre-existing 3′-OH group” to which polymerase adds the nucleotides (Mandal, 2019). Polymerase Chain Reaction (PCR) enables scientists to recreate this process by adding the nucleotides and manufacturing DNA fragments on their own. This process requires a heat-stable primer, for which Thermus aquaticus was ideal. Taq polymerase is combined with triphosphates (dNTPs) and heated to 94 degrees Celsius. This creates the conditions necessary for unpacking the DNA (which is why heat-stable Thermus aquaticus was necessary), at which point it is then cooled to 55 degrees C, thereby prompting primers to “anneal to the part of the DNA that needs to be replicated” (Dotson, 2020). It is then heated to 72 degrees C to maximize the capacity of Thermus aquaticus to create new strands, “and the helix reforms” (Dotson, 2020). This process has enabled forensic scientists to isolate DNA fragments from small samples of DNA left at crime scenes that can thereby be used to positively identify and convict criminals.