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In genetics, alleles are different forms of a gene. These variations lead to diversity in traits, like eye color or traits in animals such as fleece type. When discussing alleles, it's vital to understand the concept of dominance. A **dominant allele** is one that expresses itself visibly in the organism, even if there is only one copy. In our example with the sheep, the allele for lustrous fleece (\(L\)) is dominant. This means any sheep with at least one \(L\) allele will display a lustrous fleece.

On the other hand, a **recessive allele** requires two copies to express the trait it governs. If only one recessive allele is present, its trait remains hidden by the dominant allele. For the sheep's normal fleece trait, denoted as \(l\), it becomes visible only if the sheep inherits two \(l\) alleles (

• one from each parent).

Understanding these basic interactions between dominant and recessive alleles helps explain why only specific traits are passed on to offspring.

Heredity is the process through which traits and genetic information are passed from parents to their offspring. Every organism inherits half of its genes from each parent. In our exercise with the sheep, heredity is at play when examining the fleece type of the lamb.

The adult female sheep (ewe) displays lustrous fleece. Her offspring's wool type depends on the alleles she passes on. Because each parent contributes one allele for a trait, the ram must pass one \(l\) allele for normal fleece as he displays this phenotype. The offspring ends up with two \(l\) alleles, demonstrating this trait.

• The way traits are inherited demonstrates Mendel's basic laws of inheritance.
• By examining the phenotypes of parents and offspring, geneticists make deductions about their genotypes.

This illustrates how heredity operates in genetic inheritance, shaping traits across generations.

In genetics, distinguishing between genotype and phenotype is crucial.
**Genotype** refers to the genetic makeup of an organism—the specific alleles it possesses. In the sheep exercise, genotypes like \(LL\), \(Ll\), and \(ll\) reflect different genetic combinations for fleece.

A sheep with a genotype of **\(LL\)** or **\(Ll\)** will display a lustrous fleece phenotype, whereas a **\(ll\)** genotype leads to normal fleece.
These expressions are referred to as the **phenotype**, or the observable traits. Phenotyping is straightforward in cases where the dominant trait is expressed with the presence of a dominant allele.

• Studying both genotype and phenotype aids geneticists in predicting and understanding traits.
• The interaction between genotype and environment further influences the phenotype.

Connecting these concepts is crucial for drawing conclusions about genetic inheritance, as shown when determining the ewe's possible genotype based on the lamb's phenotype.