Introduction to Heredity and DNA

Lecture Overview

• Personal anecdote about the first week of teaching and introducing a class pet, Spike, the Texas rat snake.
• Transition to discussing heredity and DNA as foundational concepts in biology.

Classroom Anecdote

• Spike the Texas rat snake: Introduced as a classroom pet.
• Used as an example to make biology concepts (e.g., predation, mitosis) relevant and interesting.
• A student's question about Spike's parents leads to a discussion on heredity.

Heredity Basics

• Heredity: How traits are passed down from parent to offspring.
• Traits: Characteristics such as body patterns and size; influenced by DNA and environment (e.g., nourishment affecting size).

DNA Fundamentals

• DNA (Deoxyribonucleic Acid): Essential for coding traits; found in nearly all body cells.
• DNA Inheritance: Inherited from both parents; some species can reproduce asexually, inheriting DNA from one parent.
• Importance of DNA: Codes for traits (e.g., height, eye color, hair color); is present in most body cells.
• DNA in Crime Solving: DNA evidence can be used to identify individuals.

Structure of DNA

• Components:
  • Nucleotides: Building blocks of DNA with 3 parts.
    • Sugar (deoxyribose)
    • Phosphate
    • Base (Adenine, Thymine, Cytosine, Guanine)
• Base Pairing:
  • Adenine (A) pairs with Thymine (T)
  • Cytosine (C) pairs with Guanine (G)
• Mnemonic Aid: "Apples in the Tree" (A-T) and "Car in the Garage" (C-G)
• DNA Structure: Double-helix shape with bases held by hydrogen bonds.

Genes and Proteins

• Genes: Portions of DNA that code for proteins; play a significant role in trait expression.
• Protein Functions: Involved in transport, structure, acting as enzymes, protection, etc.
• Gene Regulation: Not all genes make proteins; genes can be turned on/off by various mechanisms.

Chromosomes

• Chromosome Organization: DNA compacted into units called chromosomes.
• Human Chromosome Count: 46 chromosomes in body cells, 23 in sperm/egg cells; inherited 23 from each parent.
• Genetic Code: 46 chromosomes form the complete genetic code for an individual.

Recap

• Big Picture: Chromosomes contain genes; genes are segments of DNA; DNA made up of nucleotides with specific base sequences that code for traits.
• Upcoming Topics: Dominant and recessive traits, alleles, Punnett squares (explored in heredity playlist).

Stay curious!