Basic Human Genetics - First Year of Baccalaureate

Introduction

• Topic: Basic Human Genetics
• Understanding biological instructions in cells (DNA)

Genetic Information

• DNA: Contains sequences (genes) encoded as nitrogenous bases.
• Genes: Serve as templates for functional products (RNA or proteins).
• Alleles: Variants of genes affecting product features.
• Genotype: Totality of alleles within cells.
• Phenotype: Observable characteristics derived from expressed genes.

Chromosomes

• DNA is packaged in structures called chromosomes.
• Specific regions of chromosomes containing genes are known as loci.

Inheritance Mechanisms

• Traits believed hereditary; Mendel's 1865 pea plant study foundational.
• Mendelian Genetics: Rediscovered in 1900, leading to Mendel's Laws.
• Chromosomal Theory: Alleles located on chromosomes (Boveri & Sutton).
• Genes: Term introduced in 1909 by Wilhelm Johansen.

Human Genome Project

• Initiated in 1990, concluded in 2003.
• Goal: Sequence entire human genome.

Chromosomal Inheritance

• Humans: 23 pairs of chromosomes.
  • Autosomes: 22 pairs for general body functions.
  • Sex Chromosomes: 1 pair (X and Y) for sex characteristics.
• Karyotype: Chromosome examination tool for identifying anomalies.

Chromosomal Anomalies

• Numerical Anomalies: Different number of chromosomes (e.g., Down syndrome).
• Structural Anomalies: Chromosome fragment alterations.

Sex-linked Inheritance

• X-linked Inheritance: Men inherit traits based on single X chromosome.
• Example: Color Blindness (recessive X-linked condition).

Alleles and Dominance

• Homozygous: Identical alleles for a gene.
• Heterozygous: Different alleles for a gene.
• Dominant vs. Recessive: Dominant allele masks recessive allele unless recessive is homozygous.

Multiple Alleles

• Codominance and Incomplete Dominance: Multiple alleles express different traits.
• Example: ABO Blood Group System (Codominance).

Applications of Genetics

• Understanding and combating diseases.
• Agriculture: Crop improvement and animal breeding.

Key Concepts Recap

• Genes: Units of inheritance containing coded information.
• Chromosomes: DNA packaging structures.
• Inheritance Patterns: Include sex-linked traits and multiple alleles.

Conclusion

• Genetics is crucial for medical, agricultural, and scientific advancements.
• Importance of continuous learning and adherence to health measures.