Lecture 13.3

• The chromosome theory of inheritance says that genes are located on chromosomes at a particular location.
• Sex chromosomes were first discovered in mealworms by Nettie Stevens.
• X linked inheritance are genes on the x chromosome.
• Y linked inheritance is when genes are on the y chromosome.
• linkage is the tendency for genes to be inherited together, and for genes to be inherited in pairs.
• Linked chromosomes are not inseparable, because crossing over can occur.
• Linked genes are more likely to sepparate if they are farther appart from eachother.
• You can have multiple alleles that code for the same gene. (blood type)
• Codominance is when you have both alleles are expressed in the gene.
• Incomplete dominance is when the phenotype of the heterozygote is intermediate between the phenotypes of the homozygous parents
• two or more genes can control a single trait.
• Epistasis is the interaction between two genes that affects the phenotype of the offspring
• Discrete traits are clearly different from one another
• quantitative traits very continously.
• a pedigree is a family tree
• Autosomal recessive traits are not sex linked and are reccesive.
• Sex linkage cannot be confirmed by a pedigree.
• X- linked recessive and and usually skip a generation.
• X-linked dominant traits are rare