Double helix

Definition

A double helix is the structure formed by two strands of nucleotides twisted around each other, resembling a spiral staircase. This unique shape is crucial for the stability and functionality of DNA, allowing it to store genetic information effectively and enabling processes such as replication and transcription. The double helix formation plays a significant role in how genetic information is organized within cells and how it acts as the genetic material.

5 Must Know Facts For Your Next Test

1. The double helix structure was first described by James Watson and Francis Crick in 1953, based on data from Rosalind Franklin's X-ray diffraction images.
2. The two strands of the double helix are held together by hydrogen bonds between complementary base pairs, which provide stability and specificity to the genetic code.
3. Each turn of the double helix consists of about 10 base pairs, contributing to the overall compactness and organization of DNA within the nucleus of cells.
4. The double helical structure allows for easy unwinding during DNA replication and transcription processes, facilitating the access of enzymes to the genetic code.
5. Mutations can occur when errors happen during the replication of the double helix, which can lead to variations in genetic traits or diseases.

Review Questions

• How does the structure of the double helix contribute to its stability and functionality in storing genetic information?
  • The double helix structure contributes to its stability through complementary base pairing and hydrogen bonding between the strands. This specific pairing ensures that the genetic information is accurately maintained and transmitted during cell division. Additionally, the twisting nature of the double helix protects the internal bases from damage and allows for efficient packing within cellular structures.
• Discuss how base pairing in the double helix is essential for processes like DNA replication and transcription.
  • Base pairing in the double helix is critical because it allows for accurate copying of genetic information during DNA replication. Each strand serves as a template for synthesizing a new complementary strand based on base pairing rules. During transcription, the process also relies on base pairing where RNA polymerase matches RNA nucleotides to one of the DNA strands, facilitating accurate synthesis of mRNA that carries genetic information from DNA to ribosomes.
• Evaluate the implications of errors that occur in the double helix structure during replication, considering their potential effects on genetic information.
  • Errors in the double helix during replication can lead to mutations, which may result in altered protein production or function. These mutations can have various effects, ranging from neutral to harmful, depending on their nature and location within genes. Some mutations may lead to genetic disorders or increase susceptibility to diseases, highlighting the importance of accurate replication mechanisms in maintaining genetic integrity across generations.

Related terms

Nucleotide: The basic building block of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Base Pairing: The specific pairing of nitrogenous bases (adenine with thymine, and cytosine with guanine) that stabilizes the double helix structure.

Antiparallel: Referring to the opposite orientation of the two strands in the double helix, which run in opposite directions, critical for DNA replication.