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.
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; Uracil (U) replaces Thymine in RNA.
- Pentose Sugar: Deoxyribose in DNA and ribose in RNA.
- Phosphate Group: Links the sugars, forming the nucleic acid backbone.
3. DNA Double Helix
DNA’s iconic double helix structure consists of two antiparallel strands held together 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
RNA is typically single-stranded and comes in several functional forms:
- Messenger RNA (mRNA): Conveys genetic information to the ribosome.
- Transfer RNA (tRNA): Delivers amino acids during protein synthesis.
- Ribosomal RNA (rRNA): Combines with proteins to form ribosomes.
5. Gene Expression Process
Gene expression follows the central dogma:
- Transcription: DNA is transcribed into mRNA.
- Translation: mRNA is translated into proteins at the ribosome.
This process ensures proper cellular function and organism development.
In a Nutshell
- Nucleic acids, DNA and RNA, are essential for storing and expressing genetic information.
- Nucleotides, composed of a base, sugar, and phosphate, are the monomers of nucleic acids.
- DNA's structure and RNA's versatility ensure precise transmission and expression of hereditary information.