Genetics Vocabulary List

Gregor Mendel - An Austrian monk who is known as the "father of genetics." He published his findings in 1866 on inheritance patterns in pea plants, though his work was not widely understood until 1900.

Heterozygous/Heterozygote - An organism with two different alleles for a particular gene (e.g., Aa). A heterozygous genotype contrasts with a homozygous genotype, where both alleles are the same (e.g., AA or aa).

Autosomal - Refers to genes located on any chromosome that is not a sex chromosome. Autosomal traits are inherited regardless of the individual's sex.

Chromatin - The form that DNA takes when it is loosely wrapped around histones, allowing for gene expression. When tightly wrapped, the DNA is less accessible for transcription and gene activity is reduced.

Epigenetics - The study of changes in gene expression caused by mechanisms other than changes in the DNA sequence. Environmental factors like diet, stress, and toxins can activate or deactivate genes.

Gene - A segment of DNA that contains the instructions to make a specific protein.

Genotype - The genetic makeup of an organism, representing the combination of alleles for a given gene. The genotype influences the phenotype.

Allele - A version of a gene. New alleles arise through mutations that alter the DNA sequence.

Allele Relationships:

• Codominant - Both alleles are expressed equally (e.g., AB blood type).

• Dominant - An allele that masks the effect of a recessive allele in a heterozygous genotype.

• Incomplete Dominant - A blending of traits occurs in heterozygous individuals (e.g., red and white flowers producing pink offspring).

• Recessive - An allele that is only expressed in the absence of a dominant allele (e.g., aa genotype).

Histones - Proteins around which DNA winds, helping to organize and compact the genetic material. Loosely wrapped DNA allows genes to be more active, while tightly wrapped DNA reduces gene expression.

Homozygous/Homozygote - An organism with two identical alleles for a particular gene (e.g., AA or aa). This contrasts with a heterozygous genotype (e.g., Aa).

Mendelian Trait - A trait that follows Mendel's laws of inheritance, typically involving one gene with dominant and recessive alleles.

Non-Mendelian Trait - Traits that do not follow Mendel's inheritance patterns. The five types we covered are:

Phenotype - The observable characteristics of an organism, influenced by its genotype and environmental factors.

Sex Chromosomes - Chromosomes that determine an individual's sex. Typically, individuals assigned male at birth have XY chromosomes, while those assigned female at birth have XX chromosomes. This pattern is true for most mammals.