The dominant allele is the allele that is expressed when an individual has one copy of that allele. It masks the expression of the recessive allele when present. In genetic terms, the dominant allele is represented by a capital letter, while the recessive allele is represented by a lowercase letter. When an individual has two copies of the dominant allele or one copy of the dominant allele and one copy of the recessive allele, the dominant trait will be expressed. **

The gene pool refers to the total collection of genes in a population, including all the different alleles for each gene. Allele frequency, on the other hand, refers to the proportion of a specific allele in a population's gene pool. In other words, allele frequency is a measure of how common a particular version of a gene is within a population. Therefore, while the gene pool encompasses all the genetic variation in a population, allele frequency specifically focuses on the frequency of individual alleles within that gene pool. **

Selection refers to the process by which certain traits or alleles become more or less common in a population over time. Selection pressure refers to the environmental factors that influence the fitness of individuals with different traits, leading to differential survival and reproduction. When the allele frequency increases, it means that a particular allele becomes more common in the population. This can occur as a result of natural selection favoring individuals with that allele, leading to its increased prevalence in the population over successive generations. **

Allele frequency is calculated by counting the number of times a specific allele appears in a population and dividing it by the total number of alleles for that gene in the population. This can be represented as a fraction or a percentage. For example, if there are 200 individuals in a population and 300 alleles of a specific gene, and 100 of those alleles are the "A" allele, the frequency of the "A" allele would be 100/300 = 0.33 or 33%. **

A dominant allele is a genetic variant that is expressed when present in a single copy in an individual's genotype. It masks the expression of the corresponding recessive allele. On the other hand, a recessive allele is only expressed when an individual has two copies of it in their genotype. In a heterozygous individual (having one dominant and one recessive allele), the dominant allele will be expressed, while the recessive allele will be masked. This is the basis of Mendelian genetics and inheritance patterns. **

The term "sick allele" refers to a specific variant of a gene that is associated with a disease or disorder. This allele may result in a malfunctioning or non-functioning protein, leading to the development of a particular illness. In genetic terms, a sick allele is considered a pathogenic or disease-causing variant. Understanding the presence of sick alleles can be crucial for diagnosing and treating genetic disorders. **

Allele designation refers to the specific label or symbol used to represent a particular version of a gene. Each allele designation is typically represented by a letter or combination of letters, such as A, B, or AB. These designations are used to distinguish between different variations of a gene that can produce different traits or characteristics. For example, in the ABO blood group system, the alleles for blood type are designated as A, B, and O. **

An allele pair refers to the two forms of a gene that an individual inherits from their parents. Each allele in the pair can be the same (homozygous) or different (heterozygous), and they determine the specific trait or characteristic that is expressed in an organism. Allele pairs are important in genetics as they influence the phenotype, or physical appearance, of an individual. **