Exploring DNA and Cell Functions

What is the first step in the DNA replication process?

• Unwinding of the DNA double helix

• Formation of the replication fork

• Proofreading of the new DNA strand

Answer explanation

The first step in DNA replication is the unwinding of the DNA double helix. This process separates the two strands, allowing the replication machinery to access the genetic information for copying.

Which enzyme is primarily responsible for adding new nucleotides during DNA replication?

• Helicase

• DNA polymerase

Answer explanation

DNA polymerase is the enzyme that adds new nucleotides to the growing DNA strand during replication, ensuring accurate copying of the genetic material. Other enzymes like helicase and ligase have different roles.

What is the basic structural unit of a chromosome?

• Nucleotide

• Chromatid

• Nucleosome

Answer explanation

The basic structural unit of a chromosome is the nucleosome, which consists of DNA wrapped around histone proteins. This structure helps package DNA into a compact form, allowing it to fit within the cell nucleus.

Which of the following best describes the role of DNA in cells?

• DNA stores genetic information.

• DNA transports nutrients within the cell.

• DNA acts as a structural component of the cell membrane.

Answer explanation

DNA stores genetic information, which is essential for the development, functioning, and reproduction of all living organisms. The other options incorrectly describe the functions of DNA.

During which stage of cell differentiation do cells become specialized in structure and function?

• Proliferation

• Differentiation

Answer explanation

During differentiation, cells undergo changes that lead to their specialization in structure and function, making this the correct stage for cell specialization.

What is the shape of the DNA molecule?

• Single helix

• Double helix

• Triple helix

• Linear strand

Answer explanation

The DNA molecule is shaped like a double helix, which consists of two intertwined strands. This structure is crucial for its function in storing and transmitting genetic information.

Which part of the chromosome is responsible for holding the two sister chromatids together?

• Telomere

• Centromere

• Chromatin

Answer explanation

The centromere is the region of the chromosome that holds the two sister chromatids together, ensuring proper separation during cell division. Other options like telomeres, chromatin, and histones serve different functions.

What is the function of helicase in DNA replication?

• Unzipping the DNA strands

• Adding nucleotides to the growing DNA strand

Answer explanation

Helicase plays a crucial role in DNA replication by unzipping the DNA strands, separating the double helix into two single strands. This allows other enzymes to access the DNA for replication.

Which of the following is NOT a function of DNA?

• Encoding genetic information

• Catalyzing chemical reactions

• Directing protein synthesis

Answer explanation

DNA encodes genetic information, directs protein synthesis, and replicates itself. However, it does not catalyze chemical reactions; that role is typically performed by proteins called enzymes.

What is the primary function of DNA polymerase during DNA replication?

• Unwinding the DNA double helix

• Adding nucleotides to the new DNA strand

• Sealing gaps between Okazaki fragments

Answer explanation

The primary function of DNA polymerase during DNA replication is adding nucleotides to the new DNA strand, ensuring accurate synthesis of the new DNA complementary to the template strand.