Chapter 12

1. Chapter 12 Inheritance Patterns and Human Genetics

2. Sex Determination -Thomas Hunt Morgan experimented with fruit flies -Each had four pairs of homologous chromosomes -X and Y chromosomes are discovered -All other chromosomes are called autosomes -XX = Female XY = Male Chromosomes and Inheritance

3. Sex Linkage -Morgan Hypothesized that more chromosomes could be carried by the X chromosome than the Y chromosome -Genes found on the Y Chromosomes are ‘Y Linked Genes’, genes found on the X chromosome are ‘X Linked Genes’

4. Linkage Groups -Linkage groups are genes located on one chromosome -Morgan’s demonstrations the existence of linkage groups by: Crossing GGLL (Grey,Long Winged) with itself to create F1 generation. Afterwards, he crossed heterozygous GgLl with GgLl to produce the F2 generation Phenotypic ration turned out to be 9:3:3:1 -A few of his experiments on linkage groups came out wrong because of mutations

5. Chromosome Mapping -Genes distance determines likelihood of the gene crossing over -The more offspring showing traits, the farther apart they are located on the chromosome -A chromosome map is a diagram that shows the linear sequence of genes on a chromosome -A map unit is the distance for a 1 percent crossover rate and is used in making chromosome maps.

6. Mutation -A mutation is a change of a cell. A germ cell mutation is a mutation occurring in a germ cell also know as a gamete. -Somatic mutation occur in a organism body cells and can affect the organism itself. -Lethal mutations are mutations that often cause death before birth. -Chromosome Mutations: Change in the structure of the chromosome -Gene Mutation: DNA is mutated

7. Chromosome Mutation -A deletion is the loss of a chromosome piece -Inversion is when the chromosome detaches and reattaches itself -Nondisjunction is the failure of a chromosome to separate from its homologue during meiosis. -This causes the gamete to receive an extra copy of the chromosome. This will cause life challenging disorders.

8. Gene Mutations -Point Mutation is the substitution, addition, or removal of a single nucleotide. This creates a new codon. -Common examples of point mutations are Substitution mutation is when a protein is replaced by another one Deletion is when one or more nucleotides are lost Addition is the adding of a nucleotide -Frame shift mutation the addition or removal of a continuously erroring codon.

9. Pedigree Analysis A pedigree is a family record showing a single trait and how it moves around in the family. Repeated phenotypes arecalled patterns of inheritance

10. Genetic Traits and Disorders -Genetic Disorders are genetically based disorders -One example is Huntington disease. Mild forgetfulness, irritable, muscle control loss, spasms, mental health degrades. -Single allele traits are overlarge amounts of traits controlled by a single allele. -A genetic marker is a section of DNA that has a relation to another nearby strand of DNA -Multiple allele traits are groups are three alleles that control just one gene. -Blood type is determined by multiple allele traits

11. Polygenic Traits, and X Linked Traits -A Polygenic trait is a a trait controlled by two or more genes. Skin colour is the best example, where six different genes mix together to produce the correct pigment. -Colour-blindness is a X linked trait. -Haemophilia is also X linked and prevents blood clotting in its victims. -There are many other X Linked traits that cause diseases, though most the traits are not dangerous.