Presentation on theme: "Organisms have thousands of genes, organized into chromosomes, which determine what the animal looks like and what it can do."— Presentation transcript:
Organisms have thousands of genes, organized into chromosomes, which determine what the animal looks like and what it can do.
In RoboRiot each robot has one gene with two “alleles”. Each robot contributes one “allele” to the recycler.
In humans each gene has two alleles. Each parent contributes one allele for a trait.
Heredity: An offspring gets one allele related to a trait from each of its parents. The two alleles are responsible for that trait in the offspring. Alleles determine trait
When the two alleles in a gene are different for a trait, the gene is heterozygous. When the two alleles in a gene are the same for a trait, the gene is homozygous.
When an organism has two alleles that are the same for a trait, both determine the trait. When an organism has two different alleles for a trait, only one trait is expressed.
The allele that is not expressed as a trait is called recessive. Trait: brown eyes The allele that determines the trait is called dominant. dominant recessive
The appearance of an organism is called its phenotype. All the information in the genes, both dominant and recessive, defines an organism’s genotype.
For the trait of brown or blue eye-color in humans, there are three possibilities: GenotypePhenotype homozygous brown homozygous blue heterozygous brown Because brown is dominant and blue is recessive. brown eyes blue eyes brown eyes
Eye-color Genotype Possibilities Mother’s GenotypeFather’s GenotypeOffspring’s Genotype Possibilities homozygous blue heterozygous brown heterozygous brown heterozygous brown homozygous brown homozygous brown homozygous blue homozygous blue homozygous brown heterozygous brown heterozygous brown homozygous blue heterozygous brown heterozygous brown homozygous brown homozygous blue homozygous brown homozygous blue homozygous brown
The alleles in some genes are neither dominant nor recessive. Both alleles are expressed when the genotype is heterozygous. This is called co-dominance. Blood Type BB B AA A
When alleles are co-dominant: ABAB AABB The genotype is always heterozygous The phenotype is the result of both alleles AA BB
A species is defined as organisms that resemble one another, can mate, and produce offspring that can reproduce. etc…