My internship in laboratory on 2025.12.16

Morning: DNA Amplification (PCR)
A standard PCR reaction typically consists of five basic components:

1. Template DNA: Contains the target DNA fragment to be amplified.
2. Primers: A pair of artificially synthesized short single-stranded DNA fragments (usually 18–25 nucleotides) that are complementary to the sequences at the 3' ends of the two strands of the target fragment. Primers determine the specificity and location of amplification.
3. Taq DNA Polymerase: A heat-resistant DNA polymerase that catalyzes the synthesis of new strands at high temperatures (approximately 72°C).
4. Deoxyribonucleotide Triphosphates (dNTPs): The building blocks for DNA strand synthesis, including dATP, dTTP, dCTP, and dGTP.
5. Buffer Solution: Provides the optimal working environment for the enzyme, usually containing Mg²⁺ (an essential cofactor for Taq polymerase).

Components 3, 4, and 5 are typically premixed in one solution, which is then combined with component 2 to form a ready-to-use master mix.
The prepared master mix is dispensed in fixed amounts into PCR tubes, followed by the addition of the DNA template. The tubes are then placed into the PCR machine.

The PCR process involves repeating the following three steps, typically for 25–40 cycles:

1. Denaturation: High temperature breaks the hydrogen bonds of the double-stranded template DNA, separating it into two single strands.
2. Annealing: The temperature of the reaction system is lowered, allowing the primers to bind specifically to complementary sequences on the single-stranded template DNA.
3. Extension: The polymerase starts from the 3' end of the primers and synthesizes complementary new strands following the template sequence.

All three steps are carried out automatically within the PCR machine.

Afternoon: Fungal Sampling
Place three small steel beads into each centrifuge tube. Then, carefully extract a small portion of each sample without exposing it to air and transfer it into the corresponding centrifuge tube.
The prepared samples are then sent for mechanical grinding (using the steel beads) via shaking.