Introduction to Genetics - Miss Angler's Biology Class

Overview

• Introduction to basic genetics.
• Reminder to check grade 12 playlist for more detailed genetic topics.

Key Concepts

Genetic Material in Cells

• All cells contain a chromatin network within the nucleus.
• During cell division (mitosis or meiosis), the chromatin condenses into chromosomes.
• Humans have 46 chromosomes, which are condensed DNA pieces.

DNA and Genes

• DNA is the code for all proteins in the body.
• Genes: Sections of DNA coding for specific characteristics (e.g., height, hair color).
• Genes express themselves physically, referred to as phenotypes.

Alleles

• Variation of genes are called alleles (e.g., blue-eyed, brown-eyed).
• Homologous chromosomes carry alleles for the same gene.
• Humans inherit one chromosome (and thus alleles) from each parent.

Inheritance and Alleles

Chromosome Pairs

• Each person has 46 chromosomes in homologous pairs (one maternal, one paternal).
• During reproduction (meiosis), chromosomes separate, passing on one allele to offspring.
• Each gene has two alleles, one from each parent.

Dominance in Alleles

• Dominant alleles are represented by uppercase letters; recessive alleles by lowercase.
• Phenotype is determined by genotype (allele pairs).
  • Two dominant alleles (e.g., BB) result in dominant trait.
  • One dominant and one recessive (e.g., Bb) still express the dominant trait.
  • Two recessive alleles (e.g., bb) result in expression of the recessive trait.

Genotype Terminology

• Homozygous Dominant: Both alleles are dominant (BB).
• Heterozygous: One dominant and one recessive allele (Bb).
• Homozygous Recessive: Both alleles are recessive (bb).

Recap of Important Terms

• Chromatin Network: DNA strands that condense into chromosomes during cell division.
• Chromosomes: Structures carrying DNA; humans have 46.
• Genes: Segments of DNA coding for traits.
• Alleles: Variations of a gene (different traits like eye color).
• Paternal/Maternal Chromosomes: Inherited from father/mother, respectively.
• Dominant Alleles: Expressed with one presence (uppercase).
• Recessive Alleles: Require two for expression (lowercase).
• Homozygous: Two same alleles (either dominant or recessive).
• Heterozygous: One dominant and one recessive allele.

Conclusion

• Understanding basic genetic concepts and terminology is crucial for studying biology.
• For more detailed studies, refer to additional resources and videos on genetics.