Genes

1
Genes Chromosomes
2
Chromosome Theory of Heredity

• The factors (genes) that affect the expression of
  traits are found on chromosomes.
• The chromosome theory of heredity states That
  genes are located on the chromosome and each gene
  occupies a specific place on that chromosome.
  Each chromosome contains just one allele for each
  of its genes.

3
Crossing-Over

• Crossing-Over The exchange of a section of DNA
  between chromosomes.
• Recombinants Individual organism with a new
  combination of genes due to crossing-over.

4
Mutations

• Mutation Change in genetic material.
• Chromosomal Mutation Change in number or
  structure of chromosomes.
• Nondisjunction Failure of chromosomes to
  separate.
• Polypoidy Extra set of chromosomes.
• Gene Mutation Change in the nucleotides of DNA.
• Point mutations Single nucleotide.
• Frameshift mutation The addition or deletion of
  a base, altering DNA from the point of mutation
  on.

5
Sex Linkage

• Discovered by Nettie Stevens.
• Sex Chromosome Chromosome that is different in
  males (XY) and females (XX), determine the sex of
  an organism.
• Autosomes Chromosomes that are the same in males
  and females.
• Sex-Linked Trait that is determined by a gene
  located on a sex chromosome.

6
Regulation of Gene Expression

• Incomplete Dominance Inheritance in which an
  active allele does not entirely compensate for an
  inactive allele, results in a mixed phenotype
  (blended trait).
• Ex. Red Flower White Flower Pink Flower
• Co-dominance Condition in which both alleles of
  a gene are expressed.
• Ex. A person with one blue eye and one green eye.
• Polygenic Inheritance A trait that is controlled
  by a multiple alleles of a genes (3 or more).