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DNA Questions and Answers (Q&A)

The correct answer to this question is option D – It can ACT as an exonuclease to cut single stranded DNA Taq DNA polymerase also as Taq pol is a DNA polymerase commonly used in PCR to amplify segments of DNA. The optimal level of activity of Taq pol is seen at approximately 72 degrees Celsius.

This means it functions at extremely high temperature (option A). It functions to add nucleotide triphosphates to form a new DNA strand (option B). For Taq pol to work, PCR must be done in a buffer (salt) environment. This help create a suitatable chemical environment for Taq pol to function (option C) Taq pol does not have 3’ to 5’ exonuclease activity. It only exhibits 5’ exonuclease activity.

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The correct answer to this question is option A – Extension or elongation The extension/elongation phase is where nucleotide triphosphates 9dNTPs) are added to the growing DNA strand. This is the final phase of PCR. The temperature is increased to about 72 degrees Celsius. This is the optimal temperature required for the activity of Taq DNA polymerase.

Taq DNA pol is the enzyme that added new DNA. A buffer is also required to create the right chemical environment for the function of Taq DNA polymerase. The annealing phase is the second phase in PCR. It is the phase before the extension phase. Temperature is lowered as this phase and primers attach to a specific segment of the DNA. The first phase of PCR is the Denaturation/ Separation phase. Temperature is increased to the hydrogen bonds between DNA strands.

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The correct answer is option B – AUUCGUAAGGCUC. The corresponding sequence to the DNA sequence (TAAGCATTCCGAG) as a result of transcription is AUUCGUAAGGCUC. This question is testing your knowledge of base pairing, specifically in transcription. Transcription is the process whereby the DNA sequence of a gene is copied to produce mRNA, which is needed for protein synthesis.

DNA sequence uses the complementary base pairing of guanine and cytosine, thymine, and adenosine, while on the mRNA produced, you have nucleotides such as adenine, Uracil, cytosine, and guanine. Thymine is replaced by Uracil. Since the DNA sequence is complementary to mRNA produced, a on the DNA on the DNA sequence will be matched by U on mRNA, and G on DNA sequence is matched by C on mRNA.

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The correct answer to this question is option C – Reverse transcriptase The enzyme needed to convert the RNA sequence back to its complementary DNA sequence is called reverse transcriptase. Reverse transcriptase is also known as RNA directed DNA polymerase. This enzyme is seen in retroviruses to synthesize DNA from RNA. RNA polymerase (option A) is incorrect because RNA polymerase is an enzyme used in transcription to copy DNA sequence into RNA sequence.

DNA polymerase (option B) is incorrect because DNA polymerase is an enzyme that works to synthesize new DNA during DNA replication. Ligase (option D) is incorrect because Ligase is an enzyme that joins fragments of DNA strands together. It is mostly used in DNA replication and in DNA repair.

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Techs do not terminate an incident, they ASSIST in terminating the incident

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Code for different protein. If there is a change in DNA molecule, the most likely effect will be that a different protein will be coded for. The mutation is the process whereby a change occurs in the DNA molecules; this causes a change in mRNA transcribed and, ultimately, the protein that will be translated.

If the change codes for the same amino acid as all amino acids have more than one codon, this type of mutation is known as silent mutation. If the change causes a change in amino acid, either a missense or nonsense mutation has happened. This is used to determine the functionality of the protein produced.

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There are a few common examples of DNA fingerprinting which you have probably seen even if you did not realize it. Everyone has a unique DNA fingerprint (just like actual fingerprints) so this can be used to compare with other DNA fingerprints, study a disease that someone might have, or to prove that a suspect was at a crime scene.

A common example is when detectives take a swab from a suspect's cheek. This is to collect the cheek cells and compare the suspect's DNA fingerprint to that of the DNA found at a crime scene.

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The correct answer is option C – Father. The gender of an offspring is determined by the father. The sperm carries the XY chromosome, and only one of the two is transferred to the offspring. Bear in mind that the female egg carries XX chromosomes, and only one X is transferred to the offspring. The Y chromosome is the male determine factors. It carries a gene that encodes for testis determining factor.

If an offspring gets the Y chromosome from the father, the offspring is likely to be a male with the XY chromosome. If the X chromosome is transferred from the father, the child has XX chromosomes, and it is most likely a girl child. The chromosomal sex is determined from the time of fertilization.

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The correct answer is – Replication. The process by which DNA copies itself is known as REPLICATION. The process starts with the unwinding of the double helix structure by the enzyme known as helicase. Helicase works by breaking the hydrogen bonds between the complementary base pairs. The unwinding of the DNA double helix creates the Y shaped known as the replication fork. The leading strand is the strand positioned in the 3’ to 5’ direction, and the lagging strand is oriented in 5’ to 3’ direction.

The enzyme primase adds RNA primer, which acts as the start point for DNA synthesis. DNA polymerase adds a new complementary nucleotide to the new strand made on the leading strand. The new strand is made in a 5’ to 3’ strand. On the lagging strand, RNA primers are added at different points for DNA to be synthesized. The fragments of DNA produced are called Okazaki fragments. In the end, RNA primers are removed, and DNA ligase joins the fragments of DNA together.

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The correct answer is option C – Denature DNA, Anneal Primers and Extend DNA. Polymerase Chain Reaction (PCR) is a lab technique that occurs in 3 steps. It is used in generating thousands to million copies of a specific section of DNA. In Polymerase Chain Reaction (PCR), there are three major steps. These are the denaturation of DNA, annealing primer, and the extension (elongation) step. In the denaturation step, the temperature is raised to 92 degrees Celsius.

The heat causes the breakdown of hydrogen bonds. In the annealing step, the temperature is lowered to about 50 to 60 degrees Celsius. This will allow primers to attach to specific regions on the DNA through hydrogen bonding. The annealing step takes about 10 to 20 seconds to complete. The elongation step is the final step. The temperature is raised again for the synthesis of new DNA strands.

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