bio 9

• Character


  A detectable, inheritable feature
• Trait


  Variant of a character
• Gene


  A region on a chromosome that encodes a protein
• Allele


  A variant form of a gene
• Prior to early 1900's inheritance was thought to be blend of two individuals
• Gregor Mendel identified that traits can also be inherited in discrete units as opposed to a simple blending of parental traits
• Gregor Mendel


  • Lack of "complex" traits
  • Short generation times
  • Fewer "linked" traits
• "Chance favours the prepared mind"
• Mendel kept very accurate observations and records
• There must be 2 copies of each gene
• The white trait was recessive to the purple trait (2 copies are required for the white trait)
• Purple flower is dominant so only one copy of it is needed to express the trait

  
• Locus


  A specific location on a chromosome (genes are at specific loci)

  
• Different alleles are DNA variations at a specific gene locus
• Dominant alleles mask recessive alleles
• Diploid organisms inherit 2 alleles for every character (one from each parent)
• Monohybrid Cross


  Used to track the inheritance of a single character
• Phenotype


  Observable traits of organism
• Genotype


  Allelic combinations present within an organism
• Homozygous


  Both alleles are the same
• Heterozygous


  Two different alleles
• Punnett Square


  Visual aid to help calculate offspring genotypes and phenotypes based on parental gametes
• Phenylketonuria (PKU) is a childhood developmental disorder caused by the inability to breakdown 1 of our 20 amino acids
• Mutated gene encodes an enzyme that breaks down amino acid phenylalanine
• PKU can be prevented with early detection and dietary management
• Dihybrid Cross

  Used to track the inheritance of 2 characters
• Mendel's second law: Law of Independent Assortment - Characters are independently sorted from each other (inherited separately)
• Genes (on chromosomes) separate independently during gamete formation
• Paternal genes do not have to stay together / maternal genes do not have to stay together
• Alleles that were inherited together do not have to be passed on together
• Meiotic basis of Independent Assortment

  1. During metaphase I of meiosis paternal and maternal chromosomes do not have to align on the same side to be pulled to the same gamete during anaphase

  2. Each gamete has a 50/50 chance of getting the maternal or the paternal chromosome