Gene Symbols And Punnett Squares Notes What is

Gene Symbols And Punnett Squares Notes

What is Genetics? Genetics is the scientific study of heredity. Heredity is the passing of traits from parents to offspring.

What is a trait? A trait is a specific characteristic that varies from one individual to another. Examples: Brown hair, blue eyes, tall, short, curly, straight All organism have at least two genes for every trait. They receive at least one from each parent.

What is an allele? Alleles are the different possibilities for a given trait. Every trait has at least two alleles. One from the mother and one from the father. Example: Eye color Symbol(s) – Letters are used to represent the alleles. The letters help predict the traits of the offspring. Ex. BB, Bb or bb

What are symbols? Capital letter(s) - Capitals are used to represent dominant trait. Ex. Bb or BB Dominant – mask the other trait; the trait that shows if present. BB is homozygous dominant. Lower case letter(s) - Lowercase are used to represent a recessive trait. Ex. Bb or bb Recessive – an organism with a recessive alleles for a particular trait will only exhibit that trait when the dominant allele is not present. Recessive alleles only show if both alleles are present. bb is homozygous recessive. Hybrid or heterozygous – a term used to refer to an organism that has two different alleles for the same trait Ex. Tt

What is a genotype and phenotype? Genotype- The genetic makeup of an organism; The gene or allele combination an organism has. Ex. Tt, ss or GG. Phenotype – The physical characteristics of an organism. The way an organism looks. Ex. Curly hair, straight hair, blue eyes and brown eyes. In a pea plant round or wrinkled.

What is a Punnett square? Punnett Square is a way to predict heredity by using a chart or diagram. A Punnett square shows the probability of inheriting a particular trait. The Punnett square consists of four boxes inside a square that shows the possible gene combinations. The parent’s genes or alleles are placed outside of the square. Each square represents possible offspring.