Bio1334 Genetics - Molecular Genetics - Genetic Engineering (Lecture Five)

The final step of PCR, extension, occurs at a temperature of 72 degrees Celsius. This temperature is necessary for the DNA polymerase enzyme to extend the primers and synthesize new DNA strands. At this temperature, the DNA strands are denatured, allowing the primers to anneal and the polymerase to add nucleotides to the growing DNA chain. This step is crucial for amplifying the target DNA sequence in PCR.

The second step of PCR, annealing, occurs at a temperature of 50 degrees Celsius. During this step, the DNA primers bind to the specific target sequences on the DNA template strands. The annealing temperature is crucial as it determines the specificity and efficiency of primer binding. If the temperature is too low, nonspecific binding can occur, leading to false results. Conversely, if the temperature is too high, the primers may not bind efficiently, resulting in incomplete amplification. Therefore, maintaining an annealing temperature of 50 degrees Celsius is important for successful PCR amplification.

Denaturation is the first step of PCR, where the double-stranded DNA template is heated to separate the two strands. This process occurs at a temperature of 95 degrees Celsius. At this high temperature, the hydrogen bonds holding the DNA strands together break, causing the DNA to denature into single strands. This step is crucial for subsequent steps in PCR, such as primer annealing and DNA amplification.

Transgenics refers to the process of introducing genes from one species into the genome of another species. This can be achieved by inserting a gene from an alternative species into the genome of a different species. Therefore, the correct definition of transgenics is "Genes between species, i.e. a species with an inserted gene from an alternative species."

Primers are short, single-stranded nucleic acid sequences used in PCR (polymerase chain reaction) to mark the beginning and end of a section of DNA that needs to be amplified. They serve as the starting point for DNA replication and allow the DNA polymerase enzyme to bind and initiate the amplification process. The primers are designed to be complementary to the specific DNA sequence of interest, ensuring that only the desired section of DNA is amplified.

DNA ligase is an enzyme that is responsible for joining or ligating DNA fragments together. It plays a crucial role in DNA replication and repair processes by sealing the gaps between Okazaki fragments on the lagging strand during DNA replication and by repairing DNA damage. Ligase, on the other hand, is a general term used to describe enzymes that catalyze the joining of two molecules by forming a covalent bond. In the context of DNA, DNA ligase specifically refers to the enzyme that joins DNA fragments. Therefore, both DNA ligase and Ligase are correct answers for the given question.

DNA ligase forms phosphodiester bonds in the joining of DNA. Phosphodiester bonds are formed between the phosphate group of one nucleotide and the sugar group of another nucleotide, creating a backbone for the DNA molecule. In this process, ATP is required as a source of energy to drive the formation of the bond. Therefore, the correct answer is phosphodiester, phosphodiester bond, phosphodiester bonds.

The correct definition of synthetic biology is being inspired by, but not found in, nature. This means that synthetic biology involves creating new biological systems or modifying existing ones by taking inspiration from natural systems, but not directly copying them. It involves designing and constructing novel biological parts, devices, and systems that do not occur naturally.

Restriction endonucleases are enzymes that can cut DNA at specific recognition sequences. These enzymes play a crucial role in genetic engineering and molecular biology techniques such as DNA cloning and DNA fingerprinting. They recognize specific DNA sequences and cleave the phosphodiester bonds within the DNA molecule, resulting in the generation of smaller DNA fragments. The correct answer includes both the singular form "restriction endonuclease" and the plural form "restriction endonucleases," as there are multiple types of these enzymes with different specificities.

In gel electrophoresis, a potential difference or voltage is applied along the gel. This creates an electric field that allows charged molecules, such as DNA or proteins, to move through the gel matrix. The potential difference or voltage provides the driving force for the movement of these molecules towards the opposite electrode. By applying a potential difference, the molecules can be separated based on their size and charge, allowing for the analysis and characterization of biological samples.

DNA movement in gel electrophoresis depends on its conformation (shape) and size. The shape of DNA can affect its ability to move through the gel matrix, as more compact or rigid structures may experience more resistance. Additionally, larger DNA fragments tend to migrate more slowly than smaller ones due to their increased size and mass. Therefore, both the shape and size of DNA molecules play crucial roles in determining their movement towards the positive electrode during gel electrophoresis.