Alleles Affect After Inheritance

Genotype and Phenotype Definitions

• Alleles

  • Different variants of a gene that can determine traits in an organism, such as eye color (brown, green, blue).

Dominant vs. Recessive Alleles

• Dominant Allele

  • A trait represented by a dominant allele will always show up in an organism if that allele is present.

  • Example: The allele for brown eyes is dominant and can be denoted as a capital letter (e.g., N for brown eyes).

• Recessive Allele

  • A trait represented by a recessive allele will only manifest when both alleles are recessive.

  • Example: The allele for blue eyes is recessive and can be denoted as a lowercase letter (e.g., b for blue eyes).

Genetic Influences and Environmental Factors

• Traits can be influenced by both genetic predispositions and environmental factors.

  • Genetic Factors: Variability in traits like muscle mass, height, and body fat.

  • Some individuals may be predisposed genetically to have more muscle mass, while others may have a naturally lighter body composition.

  • Environmental Factors: Such as diet, exercise, and social support systems can influence physical traits and abilities.

Mendelian Genetics

• Gregor Mendel: Known as the father of modern genetics, Mendel conducted experiments on pea plants to understand inheritance patterns.

  • His work established principles of heredity and how traits are passed along to offspring.

Punnett Squares

• Definition: A diagram used to predict the genetic makeup of offspring from two parents.

  • Components of Punnett squares will be covered in further detail to understand how traits are inherited in mammals.

Allele Writing Conventions

• When writing traits genetically, the following conventions apply:

  • Capital Letters: Represent dominant alleles (e.g., capital N for brown eyes).

  • Lowercase Letters: Represent recessive alleles (e.g., lowercase b for blue eyes).

Parental Alleles

• Each individual inherits two alleles for every trait, one from each parent.

• Two alleles can be:

  • Purebred: Two identical alleles (either two dominant or two recessive alleles).

  • Example: Two capital N alleles (NN) or two lowercase b alleles (bb).

  • Hybrid: Two different alleles (one dominant and one recessive).

  • Example: One capital N and one lowercase b (Nb).

Implications in Breeding and Pet Ownership

• The concept of being purebred is often referenced in animals like cats and dogs, where certain breeds may be more sought after due to their genetic purity.

• Hybrid Dogs: Many dogs are hybrids and may not conform to a single breed, impacting their registration and potential value.