DNA

Definition

DNA, or deoxyribonucleic acid, is the hereditary material in almost all living organisms that carries the genetic instructions essential for growth, development, functioning, and reproduction. It is composed of two long strands forming a double helix structure, made up of nucleotides that include a sugar, a phosphate group, and nitrogenous bases. The specific sequences of these bases encode the information needed to build proteins and regulate cellular activities.

5 Must Know Facts For Your Next Test

1. DNA is structured as a double helix, where two strands are twisted around each other, held together by hydrogen bonds between complementary bases.
2. The four nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G), with A pairing with T and C pairing with G.
3. DNA replication is a semi-conservative process, meaning each new DNA molecule consists of one original strand and one newly synthesized strand.
4. Mutations in DNA can lead to changes in protein production, which can affect an organism's traits and potentially lead to genetic disorders.
5. DNA is located primarily in the cell nucleus in eukaryotic cells but can also be found in mitochondria and chloroplasts, where it has distinct roles.

Review Questions

• How does the structure of DNA facilitate its function in encoding genetic information?
  • The structure of DNA as a double helix plays a critical role in its function. The complementary base pairing allows for the accurate replication of genetic information during cell division. Each strand serves as a template for creating a new complementary strand, ensuring that genetic instructions are faithfully passed on. Additionally, the sequence of bases along the DNA strands encodes the information necessary for building proteins, which are essential for cellular functions.
• Discuss the implications of mutations in DNA and how they can impact an organism's phenotype.
  • Mutations in DNA can result from various factors such as environmental influences or errors during replication. These mutations can lead to changes in the amino acid sequence of proteins, potentially altering their function. Depending on where they occur, some mutations may be benign while others can result in genetic disorders or contribute to diseases like cancer. Understanding these implications helps researchers develop targeted therapies and interventions for genetic conditions.
• Evaluate the significance of DNA replication and repair mechanisms in maintaining genetic stability across generations.
  • DNA replication is crucial for ensuring that genetic material is accurately transmitted from one generation to the next during cell division. The semi-conservative nature of replication helps maintain genetic stability by allowing each new cell to receive one original strand and one new strand. Additionally, cells have sophisticated repair mechanisms to correct errors that occur during replication or due to damage from environmental factors. These mechanisms are vital in preventing mutations that could lead to diseases and ensuring the integrity of the organism's genome throughout its life.

Related terms

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

Gene: A segment of DNA that contains the instructions for making a specific protein or set of proteins.

Replication: The process by which DNA makes a copy of itself before cell division.