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A. Polymerase chain reaction (PCR).

AL-AYEN UNIVERSITY

is a laboratory technique used to amplify a specific segment of DNA. This method allows researchers to obtain multiple copies of a DNA sequence from a small sample, which can be used for various applications such as genetic testing, forensics, and research.
Principle:

PCR works by using a special enzyme called Taq polymerase, which can extend and replicate DNA strands. This enzyme, along with primers and nucleotides, is mixed with the DNA sample in a reaction tube. The sample is then subjected to a series of temperature changes that cause the DNA strands to separate and allow the primers to bind to their complementary sequences. The Taq polymerase then extends the primers, creating new copies of the DNA sequence.

The most commonly used temperature cycles in PCR include:

1. Denaturation: This is typically done at a temperature of 94-98°C, where the double-stranded DNA template is separated into two single strands.

This is necessary to allow the primers to bind to the target DNA
2) Annealing: This is typically done

at a temperature of 50-65°C, where the primers anneal or bind to their complementary sequences on the template DNA. This step is necessary for the amplification of the target DNA.
3) Extension: This is typically done

at a temperature of 72°C, where the DNA polymerase enzyme extends the primers to generate new DNA strands. This step is necessary for the amplification of the target DNA

Steps for using the PCR:

Steps to use PCR

1. Prepare the DNA sample, primers, Taq polymerase, and nucleotides for the reaction.


2. Mix the components in a reaction tube and place it in a thermal cycler.


3. Run the thermal cycler program, which typically includes cycles of denaturation, annealing, and extension. 3 Run electrophoresis or other techniques

Safety and care:

Safety and care

1. Follow safety guidelines and wear appropriate PPE, such as gloves and lab coat, when handling DNA samples and reagents


2. Use clean and sterile techniques to avoid contamination of the samples


3. Properly dispose of biohazardous waste and contaminated materials


4. Regularly clean and maintain the thermal cycler to ensure proper function and prevent contamination

B. Thermal cycler:

A thermal cycler, also known as a PCR machine, is a laboratory instrument used to amplify DNA samples through the polymerase chain reaction (PCR). It uses a precise temperature control system to carry out the temperature cycles required for PCR
Principle of work:

The thermal cycler works by cycling through a series of temperature

changes to facilitate the different stages of the PCR reaction. This involves heating and cooling the sample to specific temperatures to denature the

DNA, anneal the primers, and extend the DNA strands

C. VITEK II system:

c VITEK II system

Is an automated microbial identification and antimicrobial susceptibility testing system developed by bioMérieux. It is widely used in clinical microbiology laboratories to identify microorganisms and determine their susceptibility to various antibiotics
Principle of work:

The VITEK II system uses a combination of technologies including fluorescence, spectrophotometry, and turbidimetry to identify microorganisms and determine their susceptibility to antimicrobial agents. The system works by incubating microbial isolates with different antimicrobial agents in a series of wells on a specialized card. The growth and metabolic activity of the microorganisms in each well are monitored using various sensors and probes. The resulting data is analyzed by the VITEK II software, which compares the growth patterns of the microorganisms in each well to a database of known microbial species and their corresponding antimicrobial susceptibility patterns.