Recording-2025-03-06T17:43:26

Genes and Alleles

• Gene: A single recipe for one protein.

• Alleles: Different versions of a gene (e.g., flower color in peas).

• Examples include variations in human traits such as hair texture (straight vs. curly).

Mendelian Genetics

• Mendel's Laws: Describe how genetic information segregates into gametes.

• Genotype: The genetic makeup (homozygous or heterozygous).

• Phenotype: The physical expression of the genotype (e.g., purple flowers vs. white flowers).

Punnett Squares

• Used to predict offspring genotypes from parental gametes.

• Dominant traits show in the F1 generation; recessive traits may reappear in F2.

• Genotypic Ratios in F2 Generation: 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive.

Mendelian Inheritance Patterns

• Traits often show a dominant/recessive relationship (e.g., purple is dominant over white).

• Genetic traits can be inferred from the proportions of offspring characteristics.

• Human Examples: Freckles (dominant) vs. no freckles (recessive).

Genetic Disorders

• Recessive Disorders: Albinism, cystic fibrosis, and Tay-Sachs disease often require two copies of the recessive allele to express.

• Dominant Disorders: Achondroplasia, Huntington's disease are often less common due to lower survival rates.

Genetic Testing and Pedigrees

• Used to determine inheritance patterns and risks of genetic disorders in families.

• New technologies have made genetic testing less invasive.

Codominance and Incomplete Dominance

• Incomplete Dominance: Intermediate phenotype expression (e.g., pink flowers from red and white parents).

• Codominance: Both phenotypes are equally expressed (e.g., AB blood type).

Conclusion

• Genetic inheritance follows Mendelian principles with variations like incomplete dominance and codominance.

• Understanding these patterns helps in predicting traits and assessing genetic disorders.