Introduction to Genetics - Miss Angler's Biology Class

Overview

• Introduction to genetics, covering the basic concepts.
• Recommended for more detailed study, check Miss Angler's Grade 12 playlist.
• Focus on key terms: genes, alleles, homologous chromosomes, dominant & recessive traits.

Chromatin Network and Chromosomes

• Chromatin Network: Found inside the nucleus, condenses into chromosomes during cell division (meiosis/mitosis).
• Chromosomes: Humans have 46 chromosomes, condensed DNA pieces.
  • DNA: Codes for proteins, characteristics like skin, hair, etc.

Genes and Alleles

• Gene: A section of DNA coding for a specific characteristic (e.g., height, hair color).
• Alleles: Variations of a gene.
  • Example: Eye color gene can have blue, brown, green alleles.

Homologous Chromosomes

• Pairs of chromosomes (one maternal, one paternal) carrying alleles for the same gene.
• Each gene has two alleles: one from each parent.
• Alleles are located at the same position on homologous chromosomes.

Inheritance of Alleles

• 46 chromosomes come in homologous pairs.
• During meiosis, homologous chromosomes separate, ensuring offspring inherit a mix of maternal and paternal alleles.
• Alleles are passed on separately (one allele per gene).

Dominant and Recessive Alleles

• Alleles represented by letters:
  • Dominant: Capital letters (e.g., B for brown eyes).
  • Recessive: Lowercase letters (e.g., b for blue eyes).

Phenotype vs. Genotype

• Phenotype: Physical appearance influenced by genotype.
• Genotype: Allele combinations influencing phenotype.
  • Homozygous Dominant: Two dominant alleles (e.g., BB).
  • Heterozygous: One dominant and one recessive allele (e.g., Bb).
  • Homozygous Recessive: Two recessive alleles (e.g., bb).

Key Terminology Recap

• Chromatin Network: Structure containing DNA, condenses into chromosomes.
• Chromosomes: Carry DNA; 46 in humans.
• Genes: Code for traits; sections of chromosomes.
• Alleles: Variations of genes (e.g., eye color variations).
• Dominant Alleles: Expressed with one present.
• Recessive Alleles: Require two to be expressed.
• Homozygous: Two identical alleles (dominant or recessive).
• Heterozygous: One dominant, one recessive allele.

Additional Resources

• For more in-depth study: Monohybrid, dihybrid crosses, sex-linked disorders.
• Flashcards for studying terminology.

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