Introduction to Genetics - Miss Angler's Biology Class

Introduction

• Welcome to an introduction to genetics.
• New content is posted every Tuesday and Thursday for grades 8-12.
• Membership offers exclusive videos, live lessons, and Q&A sessions.

Overview of Genetics

• Purpose: Introduction to basic genetics concepts.
• Detailed content available in the Grade 12 playlist on topics like monohybrid and dihybrid crosses, sex-linked disorders, etc.

Basics of Chromosomes

• Every cell has a chromatin network found in the nucleus.
• During cell division (meiosis or mitosis), the chromatin network condenses into chromosomes.
• Chromosome: A collection of DNA (humans have 46 chromosomes).
• DNA is the code of life, responsible for protein coding.

Genes and Alleles

• Gene: Section of DNA coding for a specific characteristic (e.g., height, hair color).
• Physical traits expressed by genes are called phenotypes.
• Allele: Variation of a gene (e.g., blue-eyed allele, brown-eyed allele).
• Homologous chromosomes carry alleles for the same genes.

Inheritance

• Humans have 46 chromosomes forming homologous pairs.
• Chromosomes are inherited from parents (maternal from mother, paternal from father).
• Each individual has two alleles for every gene, one from each parent.
• During meiosis, maternal and paternal chromosomes separate, passing only one allele.

Dominant and Recessive Alleles

• Dominant Alleles: Represented by a capital letter (e.g., B). They mask recessive alleles.
• Recessive Alleles: Represented by a lowercase letter (e.g., b). Require two for the trait to be expressed.

Genotypes and Phenotypes

• Genotype: Genetic makeup of an individual.
• Phenotype: Physical expression of genes.
• Genotype examples:
  • Homozygous Dominant: Two capital letters (BB).
  • Heterozygous: One capital and one lowercase letter (Bb).
  • Homozygous Recessive: Two lowercase letters (bb).

Terminology Recap

• Chromatin Network: DNA structure visible during interphase.
• Chromosomes: Structures carrying DNA.
• Genes: DNA segments coding for traits.
• Alleles: Variations of a gene.
• Dominant/Recessive Alleles: Determine which traits are expressed.
• Homozygous/Heterozygous: Refers to allele pairings.

Conclusion

• Regular updates on the channel with new content.
• Encourage participation in membership for additional support.