Chapter 11

What are the key criteria for genetic material?

1. Information: Must contain necessary information to construct an entire organism. 2. Replication: Must be able to accurately copy itself. 3. Transmission: Needs to be passed from cell to cell and generation to generation. 4. Variation: Must allow for changes to account for diversity in species.

What are the building blocks of DNA?

Nucleotides, which consist of a phosphate group, a deoxyribose sugar, and a nitrogenous base.

How is DNA structured?

DNA consists of a double helix formed by two strands of nucleotides linked by hydrogen bonds.

What forms the backbone of DNA?

The sugar-phosphate connections along each strand.

What holds the two strands of DNA together?

Hydrogen bonds between complementary bases.

Which bases pair together in DNA?

Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).

How many hydrogen bonds are formed between A-T pairs?

Two hydrogen bonds.

How many hydrogen bonds are formed between C-G pairs?

Three hydrogen bonds.

Who discovered the double-helix structure of DNA?

James Watson and Francis Crick.

What contribution did Rosalind Franklin make to the understanding of DNA?

She provided critical X-ray diffraction data that helped in the understanding of the DNA structure.

What is semiconservative replication?

Each new DNA molecule contains one original strand and one newly synthesized strand.

Why is semiconservative replication important?

It ensures accurate transmission of genetic material to daughter cells.

What happens during the initiation phase of DNA replication?

DNA unwinds, and replication origins are established, with helicase separating the DNA strands.

What role does primase play in DNA replication?

Primase synthesizes RNA primers to start the replication process.

What is the function of DNA polymerase during DNA replication?

DNA polymerase attaches new nucleotides to the growing strand, following the base-pairing rules.

How is the leading strand synthesized during DNA replication?

The leading strand is synthesized continuously.

How is the lagging strand synthesized during DNA replication?

The lagging strand is synthesized in Okazaki fragments.

What happens during the termination phase of DNA replication?

RNA primers are replaced with DNA, and fragments are joined by DNA ligase to form two new DNA molecules.

What is chromatin?

DNA wrapped around histone proteins, forming nucleosomes.

How are chromosomes further packaged in eukaryotic cells?

Chromatin is further coiled and folded to form compact chromosomes.

What does each eukaryotic chromosome contain?

Each eukaryotic chromosome contains a single, long molecule of DNA tightly packaged.

What is the role of histones in DNA structure?

Histones are proteins around which DNA wraps to form nucleosomes.

How does DNA replication ensure fidelity?

By following strict base-pairing rules and utilizing DNA polymerase for proofreading.

What role do Okazaki fragments play in DNA replication?

Okazaki fragments are segments of the lagging strand synthesized discontinuously during replication.

What is the difference between leading and lagging strands in DNA replication?

The leading strand is synthesized continuously, while the lagging strand is synthesized in fragments.

What is a replication fork?

The area where the DNA strands are separated to allow for replication.

What enzyme is responsible for unwinding the DNA during replication?

Helicase.

What happens to nucleosomes when DNA is replicated?

They are temporarily reorganized to allow access to the DNA strands.

In what phase of the cell cycle does DNA replication occur?

During the S phase (synthesis phase) of interphase.

What is the significance of hydrogen bonding in base pairing?

It provides specificity and stability to the DNA structure.

How does DNA's structure relate to its function as genetic material?

The double-helix structure allows for efficient storage and transmission of genetic information.

What did the Meselson-Stahl experiment demonstrate?

It provided evidence for the semiconservative model of DNA replication.

How do mutations occur in DNA?

Mutations can occur due to errors in replication, environmental factors, or spontaneous changes.

What is the role of DNA ligase in DNA replication?

DNA ligase joins Okazaki fragments on the lagging strand and seals nicks in the DNA.

What is the overall process involved in DNA replication?

Initiation, elongation, and termination.

Why is the replication of DNA considered a highly regulated process?

To prevent errors and ensure proper division of genetic material during cell division.