Human Genetics: Concepts and Applications Review

Comprehensive vocabulary flashcards covering fundamental human genetics, molecular biology, inheritance patterns, genetic technology, chromosomal abnormalities, single-gene disorders, multifactorial traits, and population genetics.

Human Genome

The complete set of genetic information encoded in DNA, consisting of all chromosomes and their genes.

DNA (Deoxyribonucleic Acid)

A double-helix molecule consisting of two coiled strands of nucleotides that stores the genetic blueprint directing cell development and function.

Nucleotide

The fundamental building block of DNA, composed of a deoxyribose sugar, a phosphate group, and a nitrogenous base.

Gene

The basic physical and functional unit of heredity; a sequence of DNA that encodes instructions for synthesizing proteins or RNA molecules.

DNA Replication

The process by which DNA is copied prior to cell division to guarantee that each new cell receives a complete complement of genetic instructions.

Transcription

The process occurring in the nucleus whereby a specific DNA sequence is copied into RNA by RNA polymerase.

Translation

The cellular process occurring at the ribosome where the nucleotide sequence of mRNA directs the assembly of amino acids into proteins.

Central Dogma

The foundational principle explaining the directional flow of genetic information: DNA $\rightarrow$ RNA $\rightarrow$ Protein.

Ribosome

The cellular organelle composed of ribosomal RNA (rRNA) and proteins that serves as the site for translation and protein synthesis.

Mitochondria

Organelles responsible for generating cellular energy in the form of ATP via cellular respiration; they contain their own maternally inherited DNA.

Rough Endoplasmic Reticulum

A membrane-bound organelle studded with ribosomes that participates in protein synthesis and protein folding.

Smooth Endoplasmic Reticulum

An organelle dedicated to lipid synthesis and the detoxification of harmful cellular substances.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for storage or export outside the cell.

Lysosome

A membrane-bound organelle containing digestive enzymes that break down cellular waste materials and debris.

Peroxisome

A cellular organelle containing enzymes that break down fatty acids and detoxify substances such as hydrogen peroxide.

Cytoskeleton

A network of protein fibers that provides structural support, maintains cell shape, and facilitates internal movement.

Centrioles

Organelles in animal cells that organize spindle fibers to assist with chromosome movement during cell division.

Alleles

Alternative versions or variant forms of a specific gene that account for variations in inherited traits.

Homozygous

A genotypic state characterized by possessing two identical alleles at a specific locus.

Heterozygous

A genotypic condition involving two different alleles at a given gene locus.

Codominance

A pattern of inheritance where two different alleles are simultaneously and equally expressed in the phenotype, as seen in AB blood type.

Carrier

An individual who carries a single recessive disease-causing allele without displaying clinical symptoms of the disorder.

Pedigree Chart

A diagram displaying family relationships and tracking the transmission of phenotypes across generations.

Point Mutation

A genetic mutation involving an alteration, insertion, or deletion of a single nucleotide base in DNA.

Missense Mutation

A point mutation that alters a codon, resulting in the substitution of one amino acid for another in the synthesized protein.

Nonsense Mutation

A mutation that converts an amino-acid-specifying codon into a premature stop codon, leading to an abnormally truncated protein.

Silent Mutation

A base substitution that does not change the specified amino acid sequence due to genetic code redundancy, leaving protein function unaffected.

Frameshift Mutation

A mutation caused by the insertion or deletion of nucleotides in numbers not divisible by three, disrupting the downstream triplet reading frame.

Proteome

The complete collection of proteins expressed by a cell, tissue, or organism under specified conditions.

Epigenetics

The study of stable, heritable changes in gene expression or cellular phenotype that occur without alterations to the underlying DNA sequence.

DNA Methylation

An epigenetic modification involving the chemical addition of methyl groups to DNA (commonly cytosines), typically silencing gene transcription.

Histone Acetylation

An epigenetic mechanism that alters chromatin structure into an open, relaxed state, allowing transcription factors access to initiate expression.

RNA Interference (RNAi)

A regulatory mechanism utilizing non-coding RNA molecules, such as siRNA, to target specific messenger RNAs for degradation, silencing expression post-transcriptionally.

Penetrance

The percentage of individuals carrying a specific genotype who visibly or measurably express the corresponding clinical phenotype.

Variable Expressivity

The range or degree of severity to which a phenotype is expressed among different individuals harboring the identical genotype.

Pleiotropy

A genetic phenomenon wherein a mutation in a single gene causes multiple, seemingly unrelated phenotypic traits or manifestations.

Epistasis

A gene interaction whereby the phenotypic expression of one gene is masked or modified by alleles of another separate gene.

Polymerase Chain Reaction (PCR)

A molecular biology technique used to generate millions of copies of a targeted, specific DNA sequence in vitro.

Gel Electrophoresis

A laboratory method that separates macromolecules, such as DNA fragments, based on molecular size and charge using an electric field.

CRISPR-Cas9

A precise gene-editing system modeled after bacterial immune defenses that uses a guide RNA to direct the Cas9 enzyme to cut target DNA.

Pharmacogenomics

The study of how an individual's genetic profile influences their response to pharmacological treatments and medications.

Aneuploidy

A chromosomal abnormality characterized by the presence of an atypical number of chromosomes, such as having an extra or missing chromosome.

Down Syndrome

A chromosomal condition typically caused by trisomy 21 (three copies of chromosome 21), leading to intellectual disability and distinctive physical features.

Turner Syndrome

A genetic condition in females caused by monosomy X ($45,X$), resulting from the absence of all or part of one X chromosome.

Klinefelter Syndrome

A genetic disorder affecting males characterized by the presence of an extra X chromosome, resulting in an $XXY$ chromosomal constitution.

Cystic Fibrosis

An autosomal recessive disorder caused by mutations in the CFTR gene, leading to disrupted chloride ion transport and thick, sticky mucus production.

Huntington's Disease

An autosomal dominant neurodegenerative disorder linked to trinucleotide repeat expansion in the HTT gene, manifesting in mid-adulthood with progressive chorea and cognitive decline.

Tay-Sachs Disease

An autosomal recessive lysosomal disorder caused by mutations in the HEXA gene and hexosaminidase A deficiency, causing GM2 ganglioside accumulation in neurons.

Multifactorial Inheritance

The transmission of traits or diseases that arise from the cumulative effects of multiple susceptibility genes interacting with environmental influences.

Threshold Model

A concept in multifactorial genetics proposing that a disease phenotype manifests only when cumulative genetic and environmental liabilities exceed a critical threshold.

Heritability

A statistical parameter estimating the proportion of phenotypic variation in a population that is attributable to genetic variation.

Genome-Wide Association Study (GWAS)

An analytical approach that scans complete genomes from large cohorts to identify single nucleotide polymorphisms (SNPs) associated with complex diseases or traits.

Single Nucleotide Polymorphism (SNP)

A widespread form of human genetic variation occurring when a single nucleotide at a specific locus in the DNA sequence differs among individuals.

p53 Gene

A critical tumor-suppressor gene that regulates the cell cycle and triggers apoptosis in cells harboring irreparable DNA damage to prevent tumorigenesis.

Natural Selection

The evolutionary mechanism by which heritable traits that improve an organism's survival and reproductive output become increasingly prevalent across generations.

Genetic Drift

Random fluctuations in allele frequencies within a gene pool from one generation to the next, having a particularly pronounced impact in small populations.

Founder Effect

A subtype of genetic drift occurring when a small subset of individuals establishes a new isolated colony, carrying only a restricted fraction of the original population's genetic diversity.

Gene Flow

The movement and exchange of genetic material between distinct populations of the same species through migration and interbreeding.

Hardy-Weinberg Equilibrium

A mathematical model stating that allele and genotype frequencies in a population remain stable across generations in the absence of evolutionary influences such as mutation, selection, and migration.

Gene Pool

The total aggregation of all alleles across every gene locus present within an interbreeding population at a given time.