Genetic inheritance

Biology (Separate Science) · GCSE · AQA · AQA GCSE Biology - Foundation (8461) · Specification point · 4.6.1.6 · Inheritance, variation and evolution · Reproduction

Monohybrid crosses using genetic diagrams

Genotype and phenotype in inheritance

Probability in genetic crosses

Chromosomal inheritance of genes and alleles

Allele dominance and zygosity

Molecular basis of genotype and phenotype

Single-gene and polygenic characteristics

Interpreting genetic family trees

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Learning Objectives

4.6.1.6 Genetic inheritance

Content	Key opportunities for skills development
$Students should be able to explain the terms: gamete chromosome gene allele dominant recessive homozygous heterozygous genotype phenotype. Some characteristics are controlled by a single gene, such as: fur colour in mice; and red-green colour blindness in humans. Each gene may have different forms called alleles. The alleles present, or genotype, operate at a molecular level to develop characteristics that can be expressed as a phenotype. A dominant allele is always expressed, even if only one copy is present. A recessive allele is only expressed if two copies are present (therefore no dominant allele present). If the two alleles present are the same the organism is homozygous for that trait, but if the alleles are different they are heterozygous. Most characteristics are a result of multiple genes interacting, rather than a single gene.$
$Students should be able to understand the concept of probability in predicting the results of a single gene cross, but recall that most phenotype features are the result of multiple genes rather than single gene inheritance.$

Content

Key opportunities for skills development

Students should be able to explain the terms: gamete chromosome gene allele dominant recessive homozygous heterozygous genotype phenotype. Some characteristics are controlled by a single gene, such as: fur colour in mice; and red-green colour blindness in humans. Each gene may have different forms called alleles. The alleles present, or genotype, operate at a molecular level to develop characteristics that can be expressed as a phenotype. A dominant allele is always expressed, even if only one copy is present. A recessive allele is only expressed if two copies are present (therefore no dominant allele present). If the two alleles present are the same the organism is homozygous for that trait, but if the alleles are different they are heterozygous. Most characteristics are a result of multiple genes interacting, rather than a single gene.

Students should be able to understand the concept of probability in predicting the results of a single gene cross, but recall that most phenotype features are the result of multiple genes rather than single gene inheritance.

Genetic inheritance (4.6.1.6) | AQA GCSE Biology - Foundation (8461) | KnowledgeSet