Mendelian Genetics Terms and Definitions

Mendelian Genetics Terms and Definitions

• Unaffected male: does not express the trait
• Unaffected Female: does not express the trait
• Affected Male: expresses the trait
• Affected Female: expresses the trait
• Mating: the act of breeding between two organisms
• Progeny: offspring produced from the mating
• Deceased: individual has died
• Date of death: denoted by the date D. 0000
• Unspecified Sex: individual's sex is unknown
• Parents closely related by blood: parents are related (for example, first cousins)
• Adoption: the act of taking another person's child into one's family
• Siblings: brothers and sisters
• Roman numerals: indicate generational numbers (I, II, III, etc.)
• Arabic Numbers: indicate individual within their generation (1, 2, 3, etc.)

Gene Expression and Allele Types

• Gene product: the functional molecule encoded by a gene, typically a protein or RNA
• Gene expression: process of producing a gene's functional product, which involves transcription and translation
• Allele: different versions of a gene
• Substitution mutation: a change in a single nucleotide
• Indel mutation: a short insertion or deletion of nucleotides, including a single nucleotide
• Missense mutation: results in a single amino acid change
• Nonsense mutation: changes an amino acid encoding codon to a stop codon
• Frameshift mutation: insertion or deletion that alters the reading frame, affecting downstream amino acids
• Coding mutation: mutations within the coding sequence of a gene
• Regulatory mutation: affects the activity of regulatory elements like promoters, enhancers, or splicing, altering gene expression
• Loss of function allele: reduces or eliminates the functional product
• Null allele or amorphic allele: no functional activity
• Partial loss of function / hypomorphic allele: reduced functional activity
• Conditional allele: only lose function under specific conditions, such as temperature-sensitive alleles
• Temperature-sensitive allele: functional only at certain temperatures
• Gain of function allele: increases or changes the functional activity
• Hypermorphic allele: increased functional activity
• Neomorphic allele: new functional activity, or the same product is expressed in a new location or time
• Dominant negative allele: a product that interferes with the wild-type product's function
• Haplosufficiency: a gene for which a single functional allele produces sufficient activity for a wild-type phenotype
• Haploinsufficiency: a gene that requires two functional alleles to produce a wild-type phenotype
• Co-dominance: both alleles' phenotypes are expressed in the heterozygote
• Incomplete dominance: heterozygote phenotype is an intermediate between the two homozygotes
• Lethal mutation: can alter Mendelian ratios in crosses
• Pleiotropy: one allele or gene can produce multiple phenotypes

Genetic Interactions

• Genetic interaction: occurs when alleles of different genes interact to produce a phenotype
• Epistasis: one gene's alleles mask the phenotypic effects of a second gene
• Recessive epistasis: a recessive allele masks the expression of another locus
• Dominant epistasis: a dominant allele masks the expression of another locus
• Complementary gene action (mutual recessive epistasis): both genes are required for a correct phenotype
• Redundancy (mutant dominant epistasis): multiple genes perform the same function
• Modifier gene: alleles that modify another gene's phenotypic effect
• Genetic complementation: observation of a wild-type phenotype when two different mutations are present in an organism
• Genetic complementation analysis: comparing mutants to determine if they complement each other, producing wild-type

Forward Genetic Screens

• Purpose: identify genes involved in a specific process or trait
• Mutagenesis: creating mutations using mutagens
• Mutagens: agents that cause mutations including radiation and chemicals
• Screening for recessive mutations: identifying mutations that only show their phenotype when homozygous
• Screening for dominate mutations: identifying mutations that show phenotype in both homozygotes and heterozygotes

CRISPR & Reverse Genetics

• CRISPR/Cas9: a bacterial immune system adapted for targeted genome editing
• Reverse genetics: starting with a gene and producing mutations to analyze their effect on phenotypes

Test your understanding of the key terms and definitions in Mendelian genetics with this comprehensive quiz. From affected individuals to gene expression, evaluate your knowledge of genetic concepts and terminology. Perfect for students studying genetics or biology.