Rucete ✏ Campbell Biology In a Nutshell
Unit 1 THE CHEMISTRY OF LIFE — Concept 5.5 Nucleic Acids Store, Transmit, and Help Express Hereditary Information
Nucleic acids are vital macromolecules responsible for the storage, transmission, and expression of genetic information in living organisms. They come in two primary forms: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
1. Types of Nucleic Acids
DNA (Deoxyribonucleic Acid): Holds the genetic blueprint for the development, functioning, and reproduction of organisms.
RNA (Ribonucleic Acid): Plays a crucial role in converting the genetic information from DNA into proteins, facilitating various biological processes.
2. Structure of Nucleotides
Each nucleotide, the building block of nucleic acids, comprises:
Nitrogenous Base: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G) in DNA; in RNA, Uracil (U) replaces Thymine.
Pentose Sugar: Deoxyribose in DNA and ribose in RNA.
Phosphate Group: Links the sugars, forming the backbone of the nucleic acid structure.
3. DNA Double Helix
DNA's iconic double helix structure consists of two strands running in opposite directions (antiparallel), connected by complementary base pairing:
Adenine pairs with Thymine (A-T)
Cytosine pairs with Guanine (C-G)
This precise pairing ensures accurate replication and transmission of genetic information.
4. RNA's Versatility
Unlike DNA, RNA is typically single-stranded and comes in various forms, each serving distinct functions:
Messenger RNA (mRNA): Conveys genetic information from DNA to the ribosomes for protein synthesis.
Transfer RNA (tRNA): Brings the appropriate amino acids to the ribosome during protein assembly.
Ribosomal RNA (rRNA): Combines with proteins to form ribosomes, the sites of protein synthesis.
5. Gene Expression Process
The flow of genetic information follows a central dogma:
Transcription: DNA is transcribed into mRNA.
Translation: mRNA is translated into a specific protein sequence at the ribosome.
This process ensures that genetic information is accurately expressed, leading to the proper functioning of cells and organisms.
In a Nutshell
Nucleic acids, DNA and RNA, are fundamental for storing and expressing genetic information.
Nucleotides, composed of a nitrogenous base, a pentose sugar, and a phosphate group, are the monomers of nucleic acids.
DNA's double helix structure and RNA's various forms facilitate the accurate transmission and execution of genetic instructions.