D1.1 SL DNA Replication

What is the primary purpose of DNA replication?

• To repair damaged tissues in the body.

• To synthesize proteins for cell function.

• The primary purpose of DNA replication is to ensure accurate transmission of genetic information to daughter cells.

• To produce energy for cellular processes.

Answer explanation

The primary purpose of DNA replication is to ensure accurate transmission of genetic information to daughter cells, allowing for proper cell division and maintenance of genetic continuity.

Explain the semi-conservative nature of DNA replication.

• DNA replication is semi-conservative because each new DNA molecule contains one original strand and one new strand.

• Each new DNA molecule consists of two original strands.

• DNA replication is conservative, with both strands being newly synthesized.

• DNA replication involves the complete breakdown of the original DNA strand.

Answer explanation

DNA replication is semi-conservative because each new DNA molecule contains one original strand and one new strand. This ensures genetic continuity, as half of the original DNA is preserved in each new molecule.

How does complementary base pairing contribute to DNA replication accuracy?

• Complementary base pairing has no effect on DNA replication accuracy.

• Complementary base pairing decreases DNA replication accuracy by allowing random base pairing.

• Complementary base pairing increases DNA replication accuracy by ensuring specific base pairing and enabling error correction.

• Complementary base pairing only affects RNA synthesis, not DNA replication.

Answer explanation

Complementary base pairing increases DNA replication accuracy by ensuring that adenine pairs with thymine and cytosine pairs with guanine, which minimizes errors. Additionally, it allows for error correction mechanisms to fix mismatches.

What role does helicase play in DNA replication?

• Helicase synthesizes new DNA strands.

• Helicase repairs DNA damage.

• Helicase unwinds the DNA strands.

• Helicase transports DNA to the nucleus.

Answer explanation

Helicase unwinds the DNA strands by breaking the hydrogen bonds between the base pairs, allowing the replication machinery to access the single strands for synthesis. This is crucial for accurate DNA replication.

Describe the function of DNA polymerase during DNA replication.

• DNA polymerase removes RNA primers from the DNA strand.

• DNA polymerase repairs damaged DNA strands.

• DNA polymerase unwinds the DNA double helix.

• DNA polymerase synthesizes new DNA strands by adding nucleotides complementary to the template strand.

Answer explanation

DNA polymerase is essential for DNA replication as it synthesizes new DNA strands by adding nucleotides that are complementary to the template strand, ensuring accurate duplication of genetic information.

What are the key steps involved in the polymerase chain reaction (PCR)?

• Denaturation, Annealing, Extension

• Separation, Binding, Synthesis

• Initiation, Elongation, Termination

• Replication, Transcription, Translation

Answer explanation

The key steps in PCR are Denaturation (separating DNA strands), Annealing (binding primers to the target sequence), and Extension (synthesizing new DNA strands). This process amplifies specific DNA segments effectively.

How do temperature changes affect the PCR process?

• PCR requires a constant temperature throughout the process.

• Temperature changes have no effect on PCR.

• Temperature changes are essential for denaturation, annealing, and extension in PCR.

• Higher temperatures are only needed for the final product stabilization.

Answer explanation

Temperature changes are crucial in PCR as they facilitate the three main steps: denaturation (separating DNA strands), annealing (binding primers), and extension (synthesizing new DNA). Without these changes, PCR cannot occur.

What is the significance of primers in PCR?

• Primers serve as a source of energy for the PCR reaction.

• Primers are used to amplify RNA instead of DNA.

• Primers are essential for initiating DNA synthesis and defining the target region in PCR.

• Primers are optional and do not affect the PCR process.

Answer explanation

Primers are crucial in PCR as they bind to specific sequences on the DNA template, providing a starting point for DNA polymerase to synthesize new DNA strands, thus defining the target region for amplification.

Explain the role of Taq polymerase in PCR.

• Taq polymerase is responsible for denaturing the DNA strands.

• Taq polymerase synthesizes new DNA strands during the extension phase of PCR.

• Taq polymerase acts as a primer for DNA synthesis.

• Taq polymerase is used to amplify RNA during PCR.

Answer explanation

Taq polymerase is crucial in PCR as it synthesizes new DNA strands during the extension phase, allowing for the amplification of the target DNA. It does not denature DNA, act as a primer, or amplify RNA.

What is gel electrophoresis used for in molecular biology?

• To culture bacterial cells

• To visualize cell structures

• To amplify DNA sequences

• Gel electrophoresis is used for separating and analyzing biomolecules such as DNA, RNA, and proteins.

Answer explanation

Gel electrophoresis is a technique used to separate and analyze biomolecules like DNA, RNA, and proteins based on their size and charge, making it essential for various applications in molecular biology.