Important Terms in Genetics

Overview

Students develop a precise vocabulary for genetics, inheritance and variation. They connect DNA, genes, alleles and chromosomes, then distinguish genotype (genetic information) from phenotype (observable characteristics) before applying key terms to a simple Punnett square.

Learning intentions

Students will:

• define and use important terms related to genetics and inheritance
• explain how DNA, genes, alleles and chromosomes are connected
• distinguish between genotype and phenotype, and between dominant and recessive alleles
• use a Punnett square to predict possible offspring genotypes and phenotypes
• recognise that variation can result from inherited differences and mutations

Success criteria

• I can explain the meaning of the key genetics terms in my own words.
• I can show the relationship between DNA, genes, alleles, chromosomes and the genome.
• I can correctly classify an example as a genotype or phenotype.
• I can complete and interpret a simple Punnett square.

Curriculum links

• Te Mātaiaho Science — Biological Science / Organism Diversity: inheritance of traits, DNA, variation and environmental influences.
• Te Mātaiaho Science — Biological Science / Genetic material and inheritance: connecting cells, chromosomes and DNA with inheritance and development.
• Te Mātaiaho Science — Biological Science / Organism Diversity: representing the relationship between DNA, genes and chromosomes using diagrams or physical representations.
• Science capabilities: interpreting patterns, using evidence, communicating scientific ideas and participating in collaborative inquiry.

Lesson structure (60 minutes)

1. 0–7 min · Engaging starter. Display two photographs of genetically similar organisms with noticeably different characteristics in the opening comparison slide and ask, “How can organisms be similar but not exactly the same?” Students make an individual prediction, then share ideas with a partner; record responses under “inherited”, “environmental” or “unsure”. Avoid asking students to disclose personal family or medical information.

2. 7–22 min · Explicit teaching. Use the genetics explanation slides to introduce and define the terms below, pausing for students to add concise notes to the genetics vocabulary and concept worksheet.

• Genetics: the study of inheritance and variation.
• Heredity/inheritance: the passing of genetic information and traits from parents to offspring.
• Variation: differences in characteristics among individuals of the same species.
• DNA: a molecule containing genetic information.
• Gene: a section of DNA that carries information contributing to a characteristic or biological function.
• Allele: an alternative version of a gene.
• Chromosome: a packaged structure of DNA found in cells; it contains many genes.
• Genome: all the genetic material of an organism.
• Genotype: the allele combination an organism has, often written with letters such as Bb.
• Phenotype: an observable characteristic, such as seed colour; it can be influenced by genotype and environment.
• Dominant: an allele expressed in the phenotype when at least one copy is present.
• Recessive: an allele expressed in the phenotype only when two copies are present, in a simple inheritance model.
• Homozygous: having two identical alleles, such as BB or bb.
• Heterozygous: having two different alleles, such as Bb.
• Mutation: a change in DNA; its effects may be harmful, helpful or neutral.
• Punnett square: a grid used to predict possible offspring allele combinations.

Emphasise the scale relationship: a genome contains chromosomes; chromosomes contain DNA; genes are sections of DNA; alleles are versions of genes. Clarify that “dominant” does not mean stronger, better or more common.

3. 22–32 min · Guided practice. Model a cross using B for a dominant allele and b for a recessive allele: Bb × Bb. Think aloud while placing one parent’s alleles across the top and the other parent’s alleles down the side. Students complete the same cross on the guided Punnett square section, first independently and then by comparing with a partner. Check that they identify BB, Bb, Bb and bb as genotypes, and the resulting dominant or recessive characteristics as phenotypes.

4. 32–47 min · Vocabulary sorting and matching. In groups of three or four, students use the vocabulary matching activity to match terms, definitions and examples, then arrange the DNA–gene–chromosome–genome relationship as a labelled sequence. The teacher circulates, asking, “Is this describing information inside cells, or something we can observe?” and “Is this an allele combination or a characteristic?” Groups justify one match to the class. Students may use the vocabulary activity and relationship diagram slides as a reference, but should attempt explanations without copying definitions.

5. 47–55 min · Consolidation challenge. Display the application questions. Students answer three questions in their books or on the worksheet: identify the genotype and phenotype in a scenario; classify BB, Bb and bb as homozygous or heterozygous; and explain one possible source of variation. Invite several students to explain their reasoning, correcting misconceptions that phenotype means “any visible feature” or that every mutation causes disease.

6. 55–60 min · Exit ticket. Finish with the five-minute exit ticket. Students answer: define gene and allele; explain genotype versus phenotype; state the relationship between DNA and chromosomes; identify whether Bb is homozygous or heterozygous; and complete one missing cell in a simple Punnett square. Collect responses as students leave and display the final recap slide for a final silent check.

Resources

• the genetics slide deck covering the hook, teaching diagrams, activity instructions, questions and recap
• the genetics vocabulary and concept worksheet
• Projector or interactive display
• Pens or pencils and highlighters
• Board and markers
• Optional coloured counters or mini-whiteboards for modelling alleles
• Safety notes: no practical materials are required; establish respectful discussion of inherited characteristics and do not invite personal genetic or health disclosures

Assessment

• Listen to starter explanations and group discussions for accurate use of “inheritance”, “variation”, “genotype” and “phenotype”.
• Check the guided Punnett square and vocabulary matches, using questioning to identify confusion between genes and alleles or dominant and recessive.
• Use the exit ticket as assessment evidence: students should correctly define terms, explain relationships and apply a simple inheritance model. Reteach any concept missed by several students in the next lesson.

Differentiation

• Provide a dyslexia-friendly version of the vocabulary and concept worksheet with a clear sans-serif font, generous spacing, short chunks of text, bold key terms and definitions separated from examples. Offer text-to-speech, teacher read-aloud, audio explanations and coloured overlays where helpful.
• Support learners with a partially completed relationship diagram, a visual word bank, paired talk before writing, sentence starters (“A genotype is…”, “A phenotype is…”) and pre-labelled Punnett square axes.
• Use mixed-support groups and accept oral, diagrammatic or written explanations. Check understanding privately and avoid using students’ own traits as examples.
• Extension: students create a mini concept map linking all 16 terms, explain why a dominant allele is not necessarily common, or compare how an environmental factor and a mutation could each contribute to phenotype variation.