Mendelian Inheritance:
Gregor Mendel’s experiments on pea plants.
Law of Dominance: In a heterozygote, one allele can express itself and mask the expression of the other.
Law of Segregation: Alleles segregate independently during gamete formation.
Law of Independent Assortment: Alleles for different traits assort independently of each other.
Incomplete Dominance & Co-dominance:
Incomplete Dominance: Neither allele is completely dominant, resulting in an intermediate phenotype (e.g., Snapdragon flower color).
Co-dominance: Both alleles are fully expressed (e.g., AB blood type in humans).
Sex Determination:
In humans: XX (female), XY (male).
Birds: ZZ (male), ZW (female).
Honeybees: Haplo-diploidy system (unfertilized eggs become males; fertilized eggs become females).
Mutation: Sudden change in genetic material. Can be beneficial, neutral, or harmful.
Point Mutation: Change in a single base pair (e.g., Sickle Cell Anemia).
Chromosomal Disorders:
Down Syndrome: Trisomy of 21st chromosome.
Klinefelter Syndrome: XXY condition in males.
Turner’s Syndrome: Only one X chromosome in females (XO).
Genetic Disorders:
Autosomal Dominant: Huntington’s Disease.
Autosomal Recessive: Cystic fibrosis, Sickle Cell Anemia.
Sex-linked Recessive: Colour blindness, Hemophilia.
Pedigree Analysis: A chart representing family history of inheritance of a particular trait.
Molecular Basis of Inheritance:
DNA: Double helix structure (proposed by Watson and Crick). Replication mechanism.
RNA: Types (mRNA, tRNA, rRNA) and their functions in protein synthesis.
Genetic Code: Triplet code (codon) specifying amino acids.
Genome and Human Genome Project:
Genome: Complete set of genes in an organism.
Human Genome Project (HGP): Sequencing the entire human genome. Identified approx. 20,500 genes.