Introduction to Genetics and Heredity

Vocabulary-style flashcards covering the fundamentals of human genetics, Mendelian inheritance, non-Mendelian patterns, and chromosomal disorders based on the lecture notes.

$$Heredity$$

the passing of characteristics from parent to offspring through their genes

$$Phenotype$$

the outward appearance and behavior of an individual

$$Genotype$$

an organism’s genetic composition for a particular trait

$$Epigenetics$$

how factors outside of the genome influence phenotypes

$$Homozygous$$

An individual possessing two of the same alleles for a particular gene (e.g., PP for dominant or aa for recessive).

$$Heterozygous$$

An individual possessing two different alleles for a particular gene, with one dominant and one recessive allele (e.g., Bb).

$$Dominant\,allele$$

An allele that masks the effect of a recessive trait when an individual carries both versions of a trait.

$$Selective\,Breeding\,/\,Artificial\,Selection$$

The process of observing heredity to produce preferred traits, exemplified by the development of cabbage, kale, and broccoli from the Wild Mustard Plant ($Brassica\,oleracea$).

$$True-breeding$$

Distinct populations of organisms that always produce offspring with the same variant of the trait as the parents.

$$Mendel’s\,Law\,of\,Segregation$$

The principle that each gamete receives only one allele for each gene, which occurs during meiosis I.

$$Mendel’s\,Law\,of\,Independent\,Assortment$$

The principle that one trait does not influence the inheritance of another trait because different genes are located on different chromosomes which align randomly at the metaphase plate.

$$Dihybrid$$

An individual who is heterozygous for two different traits.

$$Punnett\,Square$$

A useful tool for determining the possible genetic outcomes and predictions of a cross between two individuals.

$$Tay-Sachs\,disease$$

A currently incurable condition where an enzyme is not produced and fatty substances build up in the central nervous system, leading to blindness, paralysis, and death.

$$Test-cross$$

A mating procedure used to reveal an unknown genotype by crossing an individual with an unknown genotype with a homozygous recessive individual.

$$Pedigree$$

A chart used to decipher and predict the inheritance patterns of genes, such as determining if a trait like a widow’s peak is dominant or recessive.

$$Complete\,dominance$$

A situation where the appearance of offspring always matches one of the two parental varieties.

$$Incomplete\,dominance$$

A situation where the phenotype of a heterozygote is an intermediate blend or 'in-between' the phenotypes of the two homozygotes.

$$Hypercholesterolemia$$

A human example of incomplete dominance where having one mutant FH allele results in half the normal amount of LDL receptors and increased cardiovascular risk.

$$Codominance$$

A situation where a heterozygous individual shows features of both homozygotes simultaneously, such as in AB blood types.

$$Multiple\,allelism$$

A case where a single gene has more than two possible alleles, exemplified by the ABO blood groups in humans.

$$Antigens$$

Signposts or markers in the immune system that identify whether a cell belongs in the body.

$$Antibodies$$

Immune system molecules in the bloodstream that attack foreign invaders based on antigens the individual does not possess.

$$Rh\,Markers$$

Cell surface markers determined by a single gene with two alleles ($Rh-positive$ and $Rh-negative$) that are separate from the ABO multiple allelism.

$$Sex-linked\,trait$$

A trait produced by a gene carried on the X chromosome, which results in different patterns of expression in males and females.

$$Linked\,genes$$

Genes located close together on the same chromosome that are sometimes inherited together in one bundle.

$$Polygenic\,traits$$

Continuously varying traits, such as height, that are influenced by many different genes.

$$Additive\,effect$$

The cumulative contribution of multiple genes to the ultimate phenotype of a polygenic trait.

$$Pleiotropy$$

A phenomenon where one gene influences multiple, unrelated traits, such as the allele for sickle-cell disease.

$Phenylketonuria\,(PKU)$,

A condition where a mutated gene produces a malfunctioning enzyme unable to convert phenylalanine into tyrosine, demonstrating interaction between genes and environment.

$$Chromosomal\,Aberrations$$

Alterations in entire sections of a chromosome, including deletions, relocations, or duplications of genes.

$$Cri-du-chat$$

A genetic disorder caused by a missing part of chromosome 5.

$$Translocation$$

A structural rearrangement where parts of a chromosome are exchanged with a different non-homologous chromosome.

$$Inversion$$

A structural rearrangement where a piece of a chromosome breaks and is reattached in the opposite orientation.