Genetics

• Genetics is the biology of hereditary (mechanism) and variation (diversity)
• Hereditary (inheritance) is the process of passing on of traits from parents to offspring from either sexual or asexual reproduction
• Traits (phenotype) are expressed characteristics of an individual inherited from one generation to another
• Genes (genotype) are a set of information from the DNA that encodes for specific trait or group of traits
• Generation is the descent of traits from parents to offspring
• Variation is the presence of different frequencies of traits among individuals or populations
• Genome are the organism’s complete set of genes
• Chromosome contains bundles of tightly coiled DNA located within the nucleus of every cell in the body
• Nucleosome is a subunit of chromosome where 2 turns of DNA is wrapped around a set of 8 proteins called histones
• DNA is a self-replicating macromolecule in every living organism
• Law of Segregation: only one allele is inherited from each of the parent since chromosomes separate during meiosis
• Law of Segregation uses monohybrid cross
• Law of Independent Assortment: genes of different trait do not affect other genes of different trait in expression
• Law of Independent Assortment uses dihybrid cross
• Allelic Interaction (1 gene only): interaction of alleles
• Gene Interactions is the different expressions of genes due to different interplay between genes
• Non-Allelic Interaction (2 genes): interaction of alleles in different genes
• Complete Dominance occurs when only one of the alleles is expressed in the phenotype by masking the expression of the recessive allele
• Incomplete Dominance occurs when the expression of the recessive gene is not completely masked by the expression of the dominant gene
• Co-Dominance occurs when the expression of the genes lacks dominance and recessiveness
• Overdominance occurs when the expression of the genes exceeds measurement
• Multiple Alleles: In ABO blood system, alleles A and B are co-dominant and both are dominant to O allele
• Complete Linkage between 2 chromosomes occur if they are so physically associated to each other making them physically impossible to exchange their segments with each other
• Incomplete Linkage between 2 chromosomes occur if there are crossing overs that occur during meiosis that result in different genes in offspring
• Novel Phenotype: complete dominance at both gene pairs, new phenotypes are produced from interaction between dominants and between both homozygous recessives
• Recessive Epistasis: complete dominance but recessive is epistatic, the modifier gene completely nulls the effect of the pther genes if it is recessive
• Dominant Epistasis: complete dominance but dominant is epistatic, the modifier gene completely nulls the effect of the other genes if it is dominant
• Complementary Genes: complete dominance at both gene pairs, but either gene when homozygous recessive, is epistatic to the effects of the other gene
• Duplicate Genes: complete dominance at both gene pairs, but either gene, when dominant is epistatic to the other
• Gregor Johann Mendel is known as the father of Genetics because his experimentation with pea plants lead to a great contribution to understanding heredity.