DNA

Definition

DNA, or deoxyribonucleic acid, is the hereditary material in nearly all living organisms, containing the instructions necessary for development, functioning, growth, and reproduction. This molecule is composed of two long strands that form a double helix, held together by base pairs of nucleotides. It serves as a blueprint for biological structures and processes, connecting it to other organic compounds like proteins and nucleic acids that play vital roles in life.

5 Must Know Facts For Your Next Test

1. DNA is made up of four types of nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The specific sequence of these bases encodes genetic information.
2. The double helix structure of DNA was first described by James Watson and Francis Crick in 1953, which revolutionized our understanding of genetics.
3. DNA replication is a critical process that occurs before cell division, allowing genetic information to be accurately passed on to daughter cells.
4. Mutations in DNA can lead to changes in protein synthesis and can be the cause of genetic disorders or contribute to evolutionary changes over time.
5. DNA is not only found in the nucleus of eukaryotic cells but also in mitochondria and in the case of prokaryotes, it exists in the cytoplasm as a circular chromosome.

Review Questions

• How does the structure of DNA relate to its function in living organisms?
  • The structure of DNA as a double helix allows it to store vast amounts of genetic information in a compact form. The complementary base pairing between adenine-thymine and cytosine-guanine ensures accurate replication during cell division. This precise pairing mechanism also enables the transmission of genetic information from one generation to the next, making it essential for inheritance and the proper functioning of biological systems.
• Discuss the role of nucleotides in the formation and function of DNA.
  • Nucleotides are the fundamental units that make up DNA. Each nucleotide consists of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases. The sequence of these nucleotides encodes the genetic information necessary for the development and functioning of an organism. The arrangement of nucleotides determines how genes are expressed and influences traits, making them critical for both heredity and biology as a whole.
• Evaluate the implications of DNA mutations on an organism's phenotype and its evolutionary significance.
  • DNA mutations can lead to alterations in the amino acid sequence of proteins, which may result in changes to an organism's phenotype. Some mutations can cause diseases or dysfunctions, while others may confer advantages that enhance survival or reproduction. Over time, beneficial mutations can accumulate within populations, driving evolution and contributing to the diversity of life forms. Understanding this relationship between DNA mutations and evolution is crucial for comprehending biological adaptation and species development.

Related terms

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

Chromosome: A structure within cells that contains DNA tightly coiled around proteins, which helps organize and manage the DNA during cell division.

RNA:

Ribonucleic acid, a molecule that plays several roles in the coding, decoding, regulation, and expression of genes, serving as a messenger between DNA and protein synthesis.