HW#1 (9/19/2018) Medical Biotechnology 45/70463, Fall 2018 Name: starts note tha
ID: 149744 • Letter: H
Question
HW#1 (9/19/2018) Medical Biotechnology 45/70463, Fall 2018 Name: starts note that a hard copy of the homework should be submited before our class DNA polymerases catalyze the formation of polynucleotide chains through the addition of successive nucleotides derived from deoxynucleoside triphosphates. The polymerase reaction takes place only in the presence of an this reaction in the absence of primer. (3 pt) appropriate DNA template and primer. State the reason why DNA polymerase cannot initiate 2. Describe two types of chemical bonding that DNA polymerase can catalyze during the DNA synthesis.(2p0) 3. The TATA box is the area in promotors of eukaryotes, where the DNA string first starts denaturing so that the transcription machinery can get access. The TATA box mainly consists of A-T basepairs. Why is this an advantage, considering that the DNA string should denature? (3 pt) When Kary Mullis developed his original PCR protocol, the repeated heating between cycles inactivated the DNA polymerase so it had to be added again after each cycle. How was this problem later remedied? (2 pt) 4. What makes the gene-specific transcription factors to be specific for transcription over other numerous proteins in the cell? (3 pt) 5.Explanation / Answer
Answere :
1. DNA polymerase can synthesized new DNA strand through primer because it needs an existing strand of DNA for attachment of nucleotide i.e. primer. There should be a free 3'OH group. DNA polymerase cannot start from scratch by adding nucleotides to a free single-stranded DNA strand.
2. Two type of bonding required for DNA synthesis by DNA polymerase are :
i. Hydrogen bonding : it is required for specific base pairing between nucleotides of the two DNA strands.
ii. Phosphodiester bonding : it is required for bonding between two adjacent nucleotides in a single DNA strand.
3. TATA box is the region at which the double helix opens to form the open promoter complex. TATA box consist of AT base pair, this is advantageous becuase AT base pair possess double hydrogen bonds as compare to GC base pair ehich possess triple hydrogen bonds. So, it is easy to denature AT rich region.
4. Repeated heating and cooling in the process of PCR causes inactivation of ordinary DNA polymerase. To overcome such problems, special heat stable DNA polymerase are isolated. Example is Taq polymerase isolated from Thermus acquaticus. Such enzymes are stable at high temprature and ideally suited to use in PCR.
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