Crash Course Biology - Genetics and Inheritance Overview

Introduction

• Part of the Crash Course series focused on Biology for GAMSAT Section 3.
• Targeted at non-science background students, but beneficial for science students as well.
• Emphasizes key skills and problem-solving in genetics and inheritance.
• Resources page with a checklist for study focus areas.

Key Topics Covered

1. Genes

• Definition: DNA segments that code for proteins.
• Function: Expression of genes results in physical traits.
• Chromosomes: Humans have 46 chromosomes; genes are located on these chromosomes.

2. Alleles as Gene Variants

• Alleles: Variants of a gene coding for different traits (e.g., hair color).
• Gene Variants: Different alleles produce different traits (e.g., brown, blonde, black, red hair).
• Chromosome Pairs: Individuals carry pairs of alleles for each gene.

3. Genotypes and Phenotypes

• Genotypes: Combination of alleles in an individual's genetic makeup.
  • Examples: BB (homozygous dominant), Bb (heterozygous), bb (homozygous recessive).
• Phenotypes: Physical expression of traits (e.g., brown hair, red hair).

4. Punnett Squares

• Purpose: Tool to predict possible genetic outcomes of a cross between two individuals.
• Mono-hybrid and Di-hybrid Crosses: Show inheritance patterns of one or two traits, respectively.

5. Dominance Patterns

• Complete Dominance: One allele completely masks another.
• Incomplete Dominance: Alleles blend traits (e.g., red and white = pink).
• Co-dominance: Both alleles are expressed equally.

6. Sex-linked Traits

• X-linked Traits: Traits located on the X chromosome, more common in males.
• Y-linked Traits: Traits located on the Y chromosome, male-specific.

7. Test Crosses

• Objective: Determine the genotype of an unknown individual using a homozygous recessive mate.

Application and Problem Solving

Sample GAMSAT Questions

• Question Focus: Analyze genetic crosses, inheritance patterns, and probabilities.
• Understanding Alleles: Recognize which parent alleles contribute to offspring traits.
• Genetic Mutations: Assess probability and impact on traits.

Conclusion

• Importance of understanding basic genetics for GAMSAT problem-solving.
• Future Topics: Basics of Cell Biology, Cell Membrane, Structure of DNA, and Body Systems.
• Emphasis on practical application and strengthening understanding through example questions.

Tips for Study

• Utilize provided resources and checklists for guided study.
• Focus on understanding processes and terminologies.
• Practice with sample questions to familiarize with GAMSAT style problems.

These notes encapsulate the main ideas and topics discussed in the lecture, providing a foundation for further study and application in GAMSAT preparation.