Notes on Bitesize GCSE Biology - DNA and the Genome

Overview

• Series: Bitesize GCSE Biology, Series 1: The Cell
• Episode: 4. DNA and the genome
• Release Date: 23 March 2023
• Duration: 9 minutes
• Focus: Key facts about DNA: what it is, how it's made, and how it works.

Key Concepts

DNA - Deoxyribonucleic Acid

• Definition: DNA is a molecule that carries the genetic instructions used in growth, development, functioning, and reproduction of all known living organisms.
• Structure: DNA is composed of two strands that coil around each other to form a double helix. The structure is often compared to a twisted ladder.

Components of DNA

• Nucleotides: The building blocks of DNA, consisting of a phosphate group, a sugar molecule (deoxyribose), and a nitrogenous base.
• Bases: Four types of nitrogenous bases in DNA:
  • Adenine (A)
  • Thymine (T)
  • Cytosine (C)
  • Guanine (G)
• Base Pairing: A pairs with T and C pairs with G, which are held together by hydrogen bonds.

Genome

• Definition: A genome is the complete set of DNA, including all of its genes, in an organism.
• Human Genome: Contains approximately 3 billion base pairs and about 20,000-25,000 genes.

Function of DNA

• Genetic Code: DNA contains the information needed to build and maintain an organism.
• Gene Expression: The process by which information from a gene is used to synthesize a functional gene product (often proteins).
• Replication: DNA can replicate itself, ensuring that each new cell receives a complete set of genetic instructions.

Importance of DNA

• Inheritance: DNA is responsible for heredity, passing genetic information from parents to offspring.
• Variability: Mutations in DNA can lead to genetic diversity within populations.

Conclusion

• DNA is fundamental to life, containing the instructions for the development and functioning of living organisms. Understanding DNA is crucial for fields such as genetics, medicine, and biology.