Pcr

Explanation of PCR Steps:

Denaturation (95°C):

• DNA strands separate (heat-dependent, no enzyme required)
• Non-enzymatic process

Annealing (50-65°C):

• Primers bind to template DNA
• Non-enzymatic process (hydrogen bonding)

Extension (72°C):

• Taq DNA polymerase adds nucleotides to synthesize new DNA strands
• Only enzyme-dependent step in PCR

Thus, the correct option is D: Extension only.

PCR (Polymerase Chain Reaction) is a technique used to amplify (make millions of copies of) a small amount of DNA, making it sufficient for analysis like DNA fingerprinting.

• (A) Electrophoresis: Separates DNA fragments by size but does not amplify DNA.
• (B) Chromatography: Separates molecules based on chemical properties but cannot replicate DNA.
• (D) DNA probing: Identifies specific DNA sequences using labeled probes but does not increase DNA quantity.

Thus, PCR (C) is the only technique that solves the problem of insufficient DNA samples.

The question asks for the full form of the acronym PCR, which is mentioned alongside Rapid Antigen Test and RT-PCR as diagnostic tools for COVID-19.

PCR is a foundational technique in molecular biology used to amplify (make many copies of) a specific segment of DNA. RT-PCR (Reverse Transcription PCR) is a variation used for RNA viruses like SARS-CoV-2 (the virus causing COVID-19), where the viral RNA is first reverse transcribed into DNA, which is then amplified by PCR.

The acronym PCR stands for:

• P - Polymerase: Refers to the enzyme (DNA polymerase, often Taq polymerase) that synthesizes new DNA strands.
• C - Chain: Refers to the repetitive, cyclical nature of the process where the products of one cycle serve as templates for the next, leading to exponential amplification.
• R - Reaction: Refers to the biochemical process occurring in the test tube.

Therefore, PCR stands for Polymerase Chain Reaction.

Comparing this to the options:

• Polymerase chain reaction - Correct.
• Polymerase chain reagent - Incorrect. 'R' stands for Reaction.
• Physiological chain reaction - Incorrect. 'P' stands for Polymerase.
• Physiological chain reagent - Incorrect. 'P' stands for Polymerase and 'R' stands for Reaction.

PCR Acronym

The question asks for the full form of the acronym PCR, which is mentioned alongside Rapid Antigen Test and RT-PCR as diagnostic tools for COVID-19.

PCR is a foundational technique in molecular biology used to amplify (make many copies of) a specific segment of DNA. RT-PCR (Reverse Transcription PCR) is a variation used for RNA viruses like SARS-CoV-2 (the virus causing COVID-19), where the viral RNA is first reverse transcribed into DNA, which is then amplified by PCR.

The acronym PCR stands for:

• P - Polymerase: Refers to the enzyme (DNA polymerase, often Taq polymerase) that synthesizes new DNA strands.
• C - Chain: Refers to the repetitive, cyclical nature of the process where the products of one cycle serve as templates for the next, leading to exponential amplification.
• R - Reaction: Refers to the biochemical process occurring in the test tube.

Therefore, PCR stands for Polymerase Chain Reaction.

Comparing this to the options:

• Polymerase chain reaction - Correct.
• Polymerase chain reagent - Incorrect. 'R' stands for Reaction.
• Physiological chain reaction - Incorrect. 'P' stands for Polymerase.
• Physiological chain reagent - Incorrect. 'P' stands for Polymerase and 'R' stands for Reaction.