Nucleotide

Definition

A nucleotide is the basic building block of nucleic acids, such as DNA and RNA, consisting of three components: a phosphate group, a sugar molecule, and a nitrogenous base. These structures are vital for the storage and transmission of genetic information, as they form the repeating units in the DNA and RNA strands that encode the instructions necessary for life.

5 Must Know Facts For Your Next Test

1. Nucleotides are composed of one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G) in DNA, and uracil (U) replaces thymine in RNA.
2. Nucleotides are linked together by covalent bonds between the phosphate group of one nucleotide and the sugar of another, forming a sugar-phosphate backbone.
3. The sequence of nucleotides in DNA determines the genetic code, which dictates how proteins are made and ultimately influences an organism's traits.
4. Nucleotides also play roles beyond genetic information; they are involved in energy transfer within cells, such as ATP (adenosine triphosphate), which powers various cellular processes.
5. Mutations can occur when there are changes in the nucleotide sequence, potentially leading to variations in traits or diseases.

Review Questions

• How do nucleotides contribute to the structure and function of DNA?
  • Nucleotides are essential to the structure of DNA as they form the basic units that make up the DNA strands. Each nucleotide consists of a phosphate group, a sugar molecule, and a nitrogenous base. The sequence of these nucleotides encodes genetic information that is crucial for various biological functions. Additionally, the specific pairing of nucleotides through hydrogen bonds between complementary bases helps stabilize the double helix structure of DNA.
• Analyze the role of nucleotides in both DNA and RNA and how their differences impact genetic function.
  • Nucleotides serve as the fundamental components of both DNA and RNA; however, there are key differences that affect their functions. In DNA, nucleotides contain deoxyribose sugar and use thymine as one of their bases. In contrast, RNA contains ribose sugar and uses uracil instead of thymine. These differences contribute to distinct structural properties and functions: DNA is primarily involved in long-term storage of genetic information, while RNA plays various roles in protein synthesis and gene regulation.
• Evaluate the consequences of mutations at the nucleotide level on an organism's phenotype.
  • Mutations at the nucleotide level can lead to significant changes in an organism's phenotype by altering the genetic code. These mutations can be substitutions, deletions, or insertions of nucleotides within a gene. Depending on where they occur and their nature, these changes can disrupt normal protein function or expression levels, leading to various effects on traits or even causing diseases. Understanding these mutations is crucial for fields like genetics and medicine, as they can inform treatment options for genetic disorders.

Related terms

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

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

base pairing: The specific hydrogen bonding between nitrogenous bases in nucleic acids; adenine pairs with thymine (or uracil in RNA) and cytosine pairs with guanine.