DNA double helix

Definition

The DNA double helix is the structural formation of DNA, consisting of two long strands of nucleotides that twist around each other to form a helical shape. This unique structure is essential for the storage and transmission of genetic information, allowing for accurate replication and coding of biological instructions within living organisms.

5 Must Know Facts For Your Next Test

1. The DNA double helix was first described by James Watson and Francis Crick in 1953, building on the X-ray diffraction images produced by Rosalind Franklin.
2. Each strand of the DNA double helix runs in opposite directions, known as antiparallel orientation, which is crucial for replication and function.
3. The sugar-phosphate backbone provides structural support to the DNA strands, while the nitrogenous bases are positioned on the inside, protected from environmental factors.
4. Hydrogen bonds between complementary base pairs stabilize the double helix structure, making it both strong and flexible for various biological processes.
5. The sequence of nitrogenous bases along the DNA strands encodes genetic information that determines an organism's traits and functions.

Review Questions

• How does the structure of the DNA double helix facilitate its function in storing genetic information?
  • The DNA double helix structure allows for efficient storage of genetic information due to its compact and stable formation. The specific arrangement of nucleotide sequences along the strands encodes the instructions necessary for building proteins and regulating cellular processes. Additionally, the helical shape enables easy access for enzymes during replication and transcription, ensuring that genetic information can be accurately copied and expressed.
• Discuss the significance of base pairing in maintaining the integrity of the DNA double helix during replication.
  • Base pairing is critical for maintaining the integrity of the DNA double helix during replication because it ensures that each new strand is an exact copy of the original. The specific pairing between adenine and thymine, and cytosine and guanine, allows for precise hydrogen bonding that stabilizes the structure. When DNA replicates, each strand serves as a template for synthesizing a complementary strand, thus preserving the genetic code across generations.
• Evaluate how discoveries about the DNA double helix have advanced our understanding of genetics and biotechnology.
  • Discoveries about the DNA double helix have revolutionized our understanding of genetics and biotechnology by providing insights into how genes are structured, replicated, and expressed. This foundational knowledge has enabled advancements such as gene editing technologies like CRISPR, which allow scientists to modify specific genes for research or therapeutic purposes. Furthermore, understanding DNA's structure has paved the way for developments in fields like forensic science, personalized medicine, and genetic engineering, demonstrating its profound impact on modern biology.

Related terms

Nucleotide: The basic building block of DNA and RNA, composed of a phosphate group, a sugar molecule, and a nitrogenous base.

Base pairing: The specific hydrogen bonding between nitrogenous bases in DNA, where adenine pairs with thymine and cytosine pairs with guanine.

Replication:

The process by which DNA is copied to produce two identical DNA molecules, ensuring that genetic information is passed on during cell division.