Overview
This lecture introduces the basics of heredity by explaining DNA, chromosomes, genes, and how traits are inherited in living organisms.
Introduction to Heredity
- Heredity is the passing of traits from parents to offspring.
- Traits include characteristics like patterns, size, eye color, and disease risk.
- Some traits are influenced by both genetics and environment (e.g., nutrition affecting size).
DNA: Structure and Function
- DNA (deoxyribonucleic acid) is found in most cells' nuclei and contains genetic information.
- DNA is made of building blocks called nucleotides, each with a sugar (deoxyribose), a phosphate, and a base.
- The sequence of bases (A = adenine, T = thymine, C = cytosine, G = guanine) codes for traits.
- Base pairing: A pairs with T ("apples in the tree"), C pairs with G ("car in the garage").
- DNA has two strands forming a double-helix, held together by hydrogen bonds.
Genes and Proteins
- Genes are sections of DNA that can code for proteins.
- Proteins produced by genes express traits such as eye color and also perform other roles (transport, structure, enzyme activity, protection).
- Not all DNA codes for proteins; some portions are noncoding.
- Cells use gene regulation to turn specific genes on or off.
Chromosomes and Inheritance
- DNA is organized into chromosomes with the help of proteins.
- Humans have 46 chromosomes in most cells; sperm and egg cells have 23 each.
- Offspring inherit half their chromosomes from each parent, forming their genetic code.
Recap: Organization of Genetic Material
- Chromosomes contain genes, genes are made of DNA, and DNA is made of nucleotides.
- The sequence of DNA bases determines how traits are coded and inherited.
Key Terms & Definitions
- Heredity — the passing of traits from parents to offspring.
- Trait — a characteristic coded by genes (e.g., eye color).
- DNA (Deoxyribonucleic Acid) — the molecule that carries genetic instructions.
- Nucleotide — basic unit of DNA, composed of a sugar, phosphate, and base.
- Base Pairing — A pairs with T, C pairs with G in DNA.
- Gene — a section of DNA that codes for a protein or function.
- Protein — molecule coded by genes, responsible for various cell functions.
- Chromosome — DNA packaged and organized with proteins in cells.
- Gene Regulation — mechanisms controlling whether genes are active or inactive.
Action Items / Next Steps
- Watch the heredity playlist covering reproduction, pedigrees, Punnett squares, and inheritance types.
- Review the video on gene regulation for more details.