Study guide
Genetics study guide
Genetics explains how traits are inherited and how allelic variation maps onto phenotypes. Use this hub for Mendelian foundations, then branch into molecular gene expression when you need mechanisms.
What you will learn
- Alleles, genotypes, and phenotypes
- Dominant and recessive inheritance patterns used in teaching models
- Punnett-square reasoning without overclaiming real-world simplicity
- Bridge from classical genetics to genes and chromatin regulation
Core lessons
Start with the primary article, then branch into closely related concepts.
- Gene — A gene is a DNA segment that contains information for a functional product, typically an RNA or protein.
- Allele — An allele is an alternative version of a gene found at the same locus on homologous chromosomes.
- Genotype — A genotype is an organism’s genetic makeup at one or more loci—the alleles it carries.
- Phenotype — A phenotype is an organism’s observable traits resulting from genotype and environment.
- Dominant allele — A dominant allele is expressed in the phenotype even when only one copy is present in a heterozygote.
- Recessive allele — A recessive allele determines phenotype only when two copies are present (in simple diploid Mendelian cases).
- Homozygous — Homozygous means having two identical alleles at a locus (AA or aa in simple notation).
- Heterozygous — Heterozygous means having two different alleles at a locus (Aa in simple notation).
- Punnett square — A Punnett square is a diagram that predicts offspring genotype probabilities from parental gametes.
- Mendelian genetics — Mendelian genetics describes inheritance patterns based on segregation and independent assortment of alleles.
- Inheritance — Inheritance is the transmission of genetic information from parents to offspring.
- Mutation — A mutation is a heritable change in DNA sequence that can create new alleles and affect phenotypes.
Comparisons
- Genotype vs phenotype — Genotype is allelic composition; phenotype is the observable trait outcome.
- Dominant vs recessive — Dominant alleles shape heterozygote phenotype; recessive alleles usually show only when homozygous.
- Homozygous vs heterozygous — Homozygous genotypes have two identical alleles; heterozygous genotypes have two different alleles.
- Gene vs DNA — DNA is the molecule; a gene is a functional information segment within DNA.
- Gene vs chromosome — A gene is a locus-scale information unit; a chromosome carries many genes as one packaged DNA molecule.
Interactive practice
Explorers
- Gene regulation explorer — Interactive conceptual map of promoters, enhancers, transcription factors, and chromatin accessibility.
Tools
Worksheets
- Genetics worksheets — Punnett squares, dihybrid crosses, Hardy–Weinberg, and genetics vocabulary.
- Punnett square worksheets — Monohybrid and dihybrid Punnett practice with explicit Mendelian assumptions.
Glossary terms
- Allele — An allele is an alternative version of a gene found at the same locus on homologous chromosomes.
- Genotype — A genotype is an organism’s genetic makeup at one or more loci—the alleles it carries.
- Phenotype — A phenotype is an organism’s observable traits resulting from genotype and environment.
Common questions
What is genetics?
Genetics is the study of genes, genetic variation, and heredity—how information is stored, transmitted across generations, and expressed as traits.
What is the difference between genotype and phenotype?
Genotype is an organism’s genetic makeup at relevant loci; phenotype is the observable trait or cellular/organismal outcome shaped by genotype plus environment and developmental context.