Understanding Inheritance (Modeling Inheritance (Punnett Square (Model…
What controls traits?
Genes and Alleles
Gene - Section of the chromosome that has genetic information for one trait
Alleles - different forms of genes
Genotype and Phenotype
Symbols for Geneotypes
Uppercase letters represent dominant alleles and lowercase letters represent recessive alleles.
Homozygous and Heterozygous
Homozygous - When the two alleles of a gene are the same.
Heterozygous - When the two alleles of a gene are different.
Phenotype - How a trait appears of is expressed.
Genotype - The two alleles that control phenotype of a trait.
One factor from each Parent controls each trait.
Chromosomes contain genetic information that controls traits.
Model used to predict possible genotypes and phenotypes of offspring.
Analyzing a Punnett Squares
If there are any capital letters in a box of a punnett square the genes for that box going to be dominant. If there are two lower case letters in a box of a punnett square the genes for that box is going to be recessive.
Using Ratios to Predict
Ratios simplify information on a punnett square make it easier to see the chances of a dominant or recessive trait being passed down to offspring.
A pedigree shows phenotype of genetically related family members and can help determine genotype.
Models are used to predict traits of offspring.
Complex Patterns of Inheritance
Types of Dominance
Incomplete dominance - when the offspring's phenotype is a combination of the parents' phenotypes
Condominance - When both alleles can be observed in a phenotype
The presence of one dominant allele produces a dominant phenotype but not all allele pairs have a dominant-recessive interaction.
Some genes have more than two alleles like human blood.
Polygenic inheritance occurs when multiple genes determine the phenotype of a trait.
Genes and the Environment
Scientists have learned that genes are not the only factors that affects phenotype but the environment plays a roll too.