Question

Define the following terms: gene, allele, dominant, recessive, true-breeding, homozygous, heterozygous, cross-fertilization, and self-fertilization.

Short answer

Gene: A sequence of DNA responsible for producing a specific protein and determining traits or characteristics. Allele: A variant form of a gene that determines different traits. Dominant: An allele that masks the effect of a recessive allele, resulting in the expression of the dominant trait. Recessive: An allele that is masked by a dominant allele, only expressed when two copies are present. True-breeding: Organisms that produce offspring with the same traits as the parents, possessing homozygous alleles for a specific trait. Homozygous: An organism with two identical alleles for a specific gene, either homozygous dominant or homozygous recessive. Heterozygous: An organism with two different alleles for a specific gene, resulting in the expression of the dominant trait. Cross-fertilization: Combining genetic material from two different organisms to produce offspring, as in sexual reproduction. Self-fertilization: The process where an organism fertilizes its own eggs, resulting in genetically identical or recombined offspring.

Step-by-step solution

Define Gene

A gene is a sequence of DNA that contains the information necessary for a cell to produce a specific protein. It is the hereditary unit transmitted from parent to offspring, which determines the traits or characteristics of an individual.

Define Allele

An allele is a variant form of a gene, which results in different traits or characteristics. Each gene has two slots on a chromosome, and these slots are filled with alleles. An individual inherits one allele from each parent, and this combination of alleles determines their traits.

Define Dominant

A dominant allele is a variant of a gene that, when present, masks the effect of the recessive allele, resulting in the expression of the dominant trait. If an individual has at least one dominant allele, the dominant trait will be expressed.

Define Recessive

A recessive allele is a variant of a gene that is masked by the presence of a dominant allele. The recessive trait is only expressed when an individual has two copies of the recessive allele, one from each parent.

Define True-breeding

True-breeding is a term used to describe organisms that, when self-fertilized or cross-fertilized with another true-breeding organism of the same trait, produce offspring with the same traits as the parents. This occurs because both parents possess homozygous alleles for a specific trait.

Define Homozygous

Homozygous refers to an individual organism with two identical alleles for a specific gene. This can result in homozygous dominant (two dominant alleles) or homozygous recessive (two recessive alleles) genotypes.

Define Heterozygous

Heterozygous refers to an individual organism with two different alleles for a specific gene. In this case, the dominant allele will be expressed, and the recessive allele will be masked.

Define Cross-fertilization

Cross-fertilization is the process of combining the genetic material from two different organisms to produce offspring. This often occurs during sexual reproduction when sperm from one organism fertilizes the egg of another organism, resulting in a combination of alleles from both parents.

Define Self-fertilization

Self-fertilization is the process where an organism fertilizes its own eggs, such as in some plants and hermaphroditic organisms. This can result in offspring that are both genetically identical to the parent and offspring with recombined genetic material.