DNA

Definition

DNA, or deoxyribonucleic acid, is a molecule that carries the genetic instructions essential for the growth, development, functioning, and reproduction of all living organisms. It is structured as a double helix, composed of two long strands of nucleotides running in opposite directions, which allows it to store and transmit biological information. The specific sequence of nucleotides within DNA encodes the instructions for building proteins, making it fundamental to cellular function and heredity.

5 Must Know Facts For Your Next Test

1. DNA is made up of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G), which pair specifically (A with T and C with G).
2. The double helix structure of DNA was discovered by James Watson and Francis Crick in 1953, providing insight into how genetic information is stored and replicated.
3. DNA replication occurs during the S phase of the cell cycle, ensuring that each daughter cell receives an identical copy of the genetic material.
4. Mutations in the DNA sequence can lead to changes in protein structure and function, which can contribute to diseases such as cancer.
5. In eukaryotic cells, DNA is located primarily in the nucleus, while prokaryotic cells contain their DNA in a region called the nucleoid.

Review Questions

• How does the structure of DNA contribute to its function in storing genetic information?
  • The structure of DNA as a double helix allows it to store genetic information efficiently due to its compact form. The specific pairing of nucleotide bases (adenine with thymine and cytosine with guanine) enables the accurate replication and transmission of genetic information during cell division. This structural integrity is crucial for maintaining genetic stability while allowing for variations through mutations that can drive evolution.
• Discuss the role of genes within DNA and how they influence an organism's traits.
  • Genes are segments of DNA that contain instructions for synthesizing proteins, which are critical for determining an organism's traits. The sequence of nucleotides in a gene dictates the amino acid sequence of a protein, ultimately influencing traits such as eye color, height, and susceptibility to certain diseases. Variations in genes can lead to differences among individuals, contributing to biodiversity within populations.
• Evaluate the implications of mutations in DNA on evolutionary processes and human health.
  • Mutations in DNA can have significant implications for both evolution and human health. On one hand, beneficial mutations may provide advantages that enhance survival and reproduction, thereby contributing to evolutionary adaptation over time. Conversely, harmful mutations can disrupt normal cellular functions and lead to health issues such as genetic disorders or cancer. Understanding these mutations helps scientists develop targeted therapies and comprehend evolutionary mechanisms that shape species.

Related terms

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

Gene: A specific segment of DNA that contains the instructions for producing a particular protein or functional RNA.

Chromosome: A structure made of DNA and proteins that organizes and packages DNA into a compact form for cell division.