Human Genetics Quiz (ODS Learning Outcomes)

Basic Principles of Human Genetics

• Chromosomes: Genetic material organized into structures; humans have 23 pairs (46 total); one pair determines sex (XX = female, XY = male).

• Genes: Segments of DNA; code for specific proteins/functions; humans have approximately 20,000-25,000 genes.

• Alleles: Alternative forms of a gene; occupy the same position on a chromosome; can be dominant or recessive. Examples of alleles might code for different eye colours or other traits.

• Genotype/Phenotype: Genotype = genetic makeup; phenotype = observable characteristics. Phenotype is influenced by both genetic and environmental factors.

• Dominance/Recessiveness: Dominant alleles mask recessive alleles in heterozygous individuals; homozygous individuals have two identical alleles.

• Mutation: Changes in DNA sequence; some inherited, others spontaneous; can affect traits.

• Polygenic Traits: Traits influenced by multiple genes and environment; show a range of expressions (e.g., height, eye color, skin color).

• Genetic Disorders: Result from mutations or abnormalities in genetic material; examples include Down syndrome, cystic fibrosis, sickle cell anemia.

• Genetic Variation: Essential for adaptation and evolution; occurs via recombination during meiosis and random mutation.

Impact of Gene Mutation in Humans

• Mutations: Changes in DNA sequence, occurring during cell division; can cause genetic illnesses (e.g., cancer) or aid in adaptation.

• DNA Damage: Endogenous reactive metabolites, medicines, and environmental mutagens (e.g., UV rays) continuously damage DNA; compromising its integrity.

• Types of Mutations: Chromosomal alterations (deletions, duplications, inversions) and point mutations (monogenic mutations at a single site).

• Inherited vs. Random Mutations: Genetic conditions arise when altered genes are inherited, increasing the risk; some mutations happen randomly.

• Examples of Genetic Disorders: Alzheimer's Disease, Cystic Fibrosis, Down Syndrome, Sickle Cell Disease.

Relevance of Human Genetics in Dentistry

• Genetic Influence on Teeth: Genes influence tooth form, size, and susceptibility to diseases (e.g., gum disease, tooth decay).

• Anomalies: Variations in tooth-development genes can cause missing teeth, crowding, misalignment.

• Anodontia/Hypodontia: Hereditary conditions; result in missing permanent teeth (congenitally); may include total or partial tooth absence.