🧬 Genetics
Heredity, genes, inheritance patterns and population genetics.
Genetics has 54 topics on LearnViz, graded from Beginner to Advanced. Pick a topic below to read its explanation, examples, FAQs and related links.
What is Genetics?
Genetics studies how traits are inherited and how genes work. It covers Mendel's laws, DNA as the carrier of hereditary information, how genes are expressed, and how variation arises through mutation and recombination.
Beginner topics (17)
Heredity
The passing of traits from parents to offspring through genetic material.
🧬 GeneticsGene
A segment of DNA that carries the instructions for making a particular protein or RNA.
🧬 GeneticsAllele
One of the alternative versions of a gene found at the same position on a chromosome.
🧬 GeneticsGenotype and Phenotype
Genotype is an organism's allele makeup; phenotype is its observable traits resulting from genes and environment.
🧬 GeneticsDominant and Recessive
A dominant allele shows its effect when present in one copy; a recessive allele only shows when two copies are present.
🧬 GeneticsHomozygous and Heterozygous
Homozygous means two identical alleles for a gene; heterozygous means two different alleles.
🧬 GeneticsChromosomes
Thread-like structures of DNA and protein carrying genes; humans have 46 in 23 pairs.
🧬 GeneticsMendel's Pea Experiments
Gregor Mendel crossed pea plants to discover the basic laws of inheritance in the 1860s.
🧬 GeneticsLaw of Segregation
The two alleles for a trait separate during gamete formation so each gamete carries only one.
🧬 GeneticsLaw of Independent Assortment
Alleles of different genes are distributed to gametes independently when the genes lie on separate chromosomes.
🧬 GeneticsPunnett Squares
A grid used to predict the possible genotypes and probabilities of offspring from a cross.
🧬 GeneticsMonohybrid Cross
A cross following one gene with two alleles, giving a 3:1 phenotype ratio in the F2 generation.
🧬 GeneticsSex Chromosomes
X and Y chromosomes determine biological sex in humans; XX is typically female and XY male.
🧬 GeneticsKaryotype
An organised picture of an individual's chromosomes arranged by size, used to detect abnormalities.
🧬 GeneticsMutations
Permanent changes in the DNA sequence that can be harmless, harmful or occasionally beneficial.
🧬 GeneticsGenetic Variation
Differences in DNA among individuals, arising from mutation, recombination and sexual reproduction.
🧬 GeneticsInherited Disorders
Conditions caused by faulty genes passed through families, such as cystic fibrosis and sickle cell disease.
🧬 GeneticsIntermediate topics (20)
Dihybrid Cross
A cross following two genes at once, giving a 9:3:3:1 phenotype ratio when genes assort independently.
🧬 GeneticsTest Cross
Crossing an unknown dominant phenotype with a homozygous recessive to reveal its genotype.
🧬 GeneticsIncomplete Dominance
The heterozygote shows an intermediate phenotype, such as pink flowers from red and white parents.
🧬 GeneticsCodominance
Both alleles are fully expressed in the heterozygote, as in the AB blood type.
🧬 GeneticsMultiple Alleles
More than two allelic forms of a gene exist in a population, like the ABO blood group alleles.
🧬 GeneticsPolygenic Inheritance
A trait controlled by many genes producing continuous variation, such as height and skin colour.
🧬 GeneticsPleiotropy
A single gene influences several apparently unrelated traits, as in Marfan syndrome.
🧬 GeneticsEpistasis
One gene masks or modifies the expression of another gene at a different locus.
🧬 GeneticsSex-Linked Inheritance
Genes on the X chromosome show different patterns in males and females, as with red-green colour blindness.
🧬 GeneticsLinked Genes
Genes close together on the same chromosome tend to be inherited together instead of assorting independently.
🧬 GeneticsCrossing Over
Exchange of segments between homologous chromosomes in prophase I that creates new allele combinations.
🧬 GeneticsPedigree Analysis
Family trees that trace a trait across generations to infer dominant, recessive or sex-linked inheritance.
🧬 GeneticsNondisjunction
Failure of chromosomes to separate in meiosis, producing gametes with extra or missing chromosomes.
🧬 GeneticsDown Syndrome
A condition caused by an extra copy of chromosome 21, also called trisomy 21.
🧬 GeneticsTurner and Klinefelter Syndromes
Sex chromosome aneuploidies: Turner is XO and Klinefelter is XXY.
🧬 GeneticsChromosomal Mutations
Large structural changes including deletions, duplications, inversions and translocations of chromosome segments.
🧬 GeneticsPoint Mutations
Changes to a single nucleotide, classed as silent, missense or nonsense depending on the effect on the protein.
🧬 GeneticsFrameshift Mutation
Insertion or deletion of nucleotides not in multiples of three that shifts the reading frame of the codons.
🧬 GeneticsHardy-Weinberg Principle
Predicts that allele and genotype frequencies stay constant in an idealised population, following p squared plus 2pq plus q squared.
🧬 GeneticsGene Pool
The total collection of alleles in all individuals of a breeding population.
🧬 GeneticsAdvanced topics (17)
Genetic Drift
Random changes in allele frequency that have strong effects in small populations, including the founder effect and bottleneck.
🧬 GeneticsGene Flow
The movement of alleles between populations through migration and interbreeding, reducing differences between them.
🧬 GeneticsQuantitative Trait Loci
Regions of the genome statistically associated with variation in continuous traits.
🧬 GeneticsHeritability
The proportion of phenotypic variation in a population attributable to genetic differences.
🧬 GeneticsGenomic Imprinting
Parent-of-origin-specific gene expression caused by epigenetic marks, as seen in IGF2 and H19.
🧬 GeneticsX-Chromosome Inactivation
One X chromosome in each female cell is silenced as a Barr body to equalise gene dosage.
🧬 GeneticsEpigenetics
Heritable changes in gene activity, through DNA methylation and histone modification, without altering the DNA sequence.
🧬 GeneticsMitochondrial Inheritance
Mitochondrial DNA is passed almost exclusively from the mother, giving maternal inheritance patterns.
🧬 GeneticsTrinucleotide Repeat Disorders
Diseases such as Huntington's caused by unstable expansion of three-base repeats.
🧬 GeneticsGenetic Linkage Mapping
Uses recombination frequencies between genes to build maps measured in centimorgans.
🧬 GeneticsTransposable Elements
Mobile DNA sequences that jump within the genome, discovered by Barbara McClintock in maize.
🧬 GeneticsGenome-Wide Association Studies
Scan many genomes for variants statistically linked to a trait or disease.
🧬 GeneticsPopulation Genetics Models
Mathematical models using selection, mutation, drift and migration to predict allele frequency change.
🧬 GeneticsPenetrance and Expressivity
Penetrance is the fraction of carriers showing a phenotype; expressivity is how strongly it appears.
🧬 GeneticsGenetic Counselling
Professional guidance that helps families understand inherited disease risk and testing options.
🧬 GeneticsHybrid Vigour
Heterosis, where crossbred offspring outperform both inbred parents in growth or yield.
🧬 GeneticsMendelian Randomisation
A method that uses genetic variants as natural experiments to infer causal effects of exposures.
🧬 GeneticsUse cases
- Medical genetics: Genetic testing identifies carriers of inherited conditions such as cystic fibrosis and helps families understand their risk.
- Agriculture: Breeders use inheritance patterns to select crops and livestock with higher yield or better disease resistance.
- Forensics: DNA profiling compares short tandem repeats to link a sample to an individual.
- Conservation: Measures of genetic diversity help decide which populations need protection.
Frequently asked questions
How many topics are covered in Genetics?
Genetics has 54 topics on LearnViz: 17 Beginner, 20 Intermediate and 17 Advanced. Each one has its own page with an explanation, use cases, FAQs and related topics.
Where should a beginner start in Genetics?
Start with the Beginner topics, such as Heredity, Gene, Allele. Once those terms feel familiar, move on to the Intermediate topics.
What are the most advanced topics in Genetics?
The Advanced level includes Genetic Drift, Gene Flow, Quantitative Trait Loci, Heritability, Genomic Imprinting. Read the Beginner and Intermediate topics first, because the Advanced ones build on them.
Can I test my knowledge of Genetics?
Yes. The Genetics quiz asks questions generated from the topic explanations, and the timed tests on LearnViz cover the same material.
What is the difference between a gene and an allele?
A gene is a segment of DNA that codes for a trait. An allele is one of the alternative versions of that gene. Most people carry two alleles for each gene, one from each parent.
Why do real results sometimes differ from a Punnett square?
A Punnett square predicts probabilities, not exact outcomes. Small families and chance fertilisation events can give ratios that differ from the expected one, especially in small samples.
Are all traits controlled by a single gene?
No. Many traits are polygenic, meaning several genes contribute, and the environment can also shape them.