Nucleotide

Definition

A nucleotide is the basic building block of nucleic acids, such as DNA and RNA, composed of three components: a phosphate group, a five-carbon sugar, and a nitrogenous base. These components work together to form the structure of DNA and RNA, enabling the storage and transmission of genetic information.

5 Must Know Facts For Your Next Test

1. Nucleotides are linked together by phosphodiester bonds to form long chains in nucleic acids.
2. Each nucleotide consists of one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G) in DNA; and adenine (A), uracil (U), cytosine (C), or guanine (G) in RNA.
3. The sequence of nucleotides in a DNA or RNA strand determines the genetic code and ultimately dictates how proteins are synthesized.
4. Nucleotides also serve other important roles in cellular metabolism, such as ATP (adenosine triphosphate) which provides energy for biochemical reactions.
5. Mutations can occur when there is a change in the nucleotide sequence of DNA, potentially leading to changes in protein function and expression.

Review Questions

• How do nucleotides contribute to the overall structure and function of DNA?
  • Nucleotides are the fundamental units that compose DNA. Each nucleotide contains a phosphate group, a sugar, and a nitrogenous base. The sequence of these nucleotides encodes genetic information, while their arrangement forms the double helix structure through base pairing. This structure allows DNA to store genetic information securely and replicate accurately during cell division.
• Discuss the role of nucleotides in protein synthesis and how they relate to the genetic code.
  • Nucleotides play a critical role in protein synthesis through messenger RNA (mRNA), which is transcribed from DNA. Each sequence of three nucleotides, known as a codon, corresponds to a specific amino acid in the growing polypeptide chain. This process ensures that the information encoded in the DNA is translated into functional proteins. Thus, nucleotides directly link genetic information to protein synthesis.
• Evaluate how mutations in nucleotide sequences can impact an organism's phenotype and evolution.
  • Mutations in nucleotide sequences can lead to changes in the amino acid sequence of proteins, potentially altering their function. This can result in phenotypic changes that affect an organism's fitness and survival. If these mutations provide an advantage or disadvantage in the environment, they can drive evolutionary changes over generations. Therefore, understanding nucleotide variations is essential for studying genetics and evolution.

Related terms

DNA: Deoxyribonucleic acid, a molecule that carries genetic instructions for the development, functioning, growth, and reproduction of all known living organisms.

RNA: Ribonucleic acid, a molecule essential in various biological roles, including coding, decoding, regulation, and expression of genes.

base pairing: The specific hydrogen bonding between nitrogenous bases in DNA or RNA that holds the two strands of the nucleic acid together.