DNA

Definition

DNA, or deoxyribonucleic acid, is the hereditary material in all known living organisms and many viruses, containing the genetic instructions essential for growth, development, functioning, and reproduction. It is composed of two long strands forming a double helix structure, where sequences of nucleotides encode the information necessary for building proteins, which play crucial roles in various biological processes.

5 Must Know Facts For Your Next Test

1. The structure of DNA was first described by James Watson and Francis Crick in 1953, revealing its double helix shape formed by two strands twisted around each other.
2. DNA replication is a fundamental process where DNA makes a copy of itself before cell division, ensuring that each new cell receives the complete set of genetic instructions.
3. Each strand of DNA is composed of four types of nucleotides, identified by their nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G), with A pairing with T and C pairing with G.
4. Mutations in DNA can lead to changes in protein synthesis, which may result in various genetic disorders or contribute to the evolution of species over time.
5. DNA is organized into chromosomes within the nucleus of eukaryotic cells, with humans having 23 pairs of chromosomes that contain thousands of genes.

Review Questions

• How does the structure of DNA relate to its function in storing genetic information?
  • The double helix structure of DNA plays a crucial role in its ability to store genetic information. The sequence of nucleotides along the strands encodes the instructions needed to synthesize proteins. The complementary base pairing between adenine and thymine, as well as cytosine and guanine, ensures accurate replication and transcription processes, allowing genetic information to be reliably passed on during cell division.
• Discuss the significance of DNA replication in the context of cell division and genetic fidelity.
  • DNA replication is vital for cell division as it ensures that each daughter cell receives an identical copy of the parent cell's genetic material. This process involves unwinding the double helix and synthesizing new complementary strands for each original strand. Accurate replication is critical for maintaining genetic fidelity; errors during this process can lead to mutations, potentially resulting in diseases or contributing to evolutionary changes.
• Evaluate the impact of mutations in DNA on protein synthesis and how this relates to biological diversity.
  • Mutations in DNA can significantly affect protein synthesis by altering the nucleotide sequence that codes for specific proteins. These changes may lead to nonfunctional proteins or entirely new proteins with different functions. Over time, such mutations contribute to biological diversity within populations, providing the raw material for natural selection. This process is fundamental to evolution, as advantageous mutations may enhance survival and reproduction in changing environments.

Related terms

RNA:

Ribonucleic acid (RNA) is a molecule similar to DNA that plays essential roles in coding, decoding, regulation, and expression of genes.

Nucleotide: A nucleotide is the basic building block of DNA and RNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base.

Chromosome: Chromosomes are long, thread-like structures made of DNA and proteins that carry genetic information; they are found in the nucleus of eukaryotic cells.