NON-MENDELIAN INHERITANCE 3

• Genetics


  A branch of biology concerned with the study of genes, genetic variation, and heredity in organisms
• Inheritance


  The process by which genetic information is passed on from parents to child
• Variation


  Any difference between cells, individual organisms, or groups of organisms of any species
• Gene


  A unit of heredity, a section of DNA that codes for a specific trait
• Genotype


  The genetic makeup of an organism, the combination of two alleles
• Phenotype


  The physical appearance, feature or trait of an organism
• Homozygous


  Having two identical alleles
• Heterozygous


  Having two different alleles
• Punnett square


  A graphical representation of the possible genotypes of an offspring arising from a particular cross or breeding event
• Gregor Mendel is considered the father of genetics for his principles that form the base for the understanding of heredity and variation
• Non-Mendelian inheritance


  A type of inheritance where the patterns of phenotypes do not coincide with those presented in Mendelian laws of inheritance
• Incomplete dominance


  • One allele does not completely dominate another allele, resulting in a new or third phenotype
• Incomplete dominance


  • Red snapdragon flower crossed with white snapdragon flower results in pink snapdragon flower
• Codominance


  • Both alleles are expressed equally in the phenotype of the heterozygote
• Codominance


  • Red flower crossed with white flower results in red and white flower
• Multiple alleles


  A gene that is controlled by more than two alleles
• Sex chromosomes


  The 23rd pair of chromosomes that determines gender, with females having XX and males having XY
• Sex-linked traits


  • Inherited through the X chromosomes
• Sex-linked trait


  • Pattern baldness
• Sex determination


  If an egg is fertilized by a sperm carrying a Y chromosome, the baby will be male. If an egg is fertilized by a sperm carrying an X chromosome, the baby will be female.
• 50% of children would be expected to be male and 50% female
• Sex-influenced traits


  • Phenotypes are different between males and females with the same genotype, expressed more frequently in one sex
• Sex-limited traits


  • Traits can only be expressed in one sex or the other, not found on the X and Y chromosomes