Topic 3: Genetics – GCSE Edexcel Higher Biology revision notes

What this topic covers

Topic 3: Genetics has 5 subtopics:

• Reproduction
• Variation and evolution
• Cell division
• The development of understanding of genetics and evolution
• Additional inheritance patterns

Topic 3: Genetics lessons by subtopic

25 lessons, grouped by subtopic.

Reproduction

• Gametes in Sexual Reproduction
• Sexual vs Asexual Reproduction and Cell Division
• What is Meiosis?: Understand how meiosis produces gametes with half the number of chromosomes through two divisions, creating genetically different cells in reproductive organs.
• Fertilisation and Development: Learn how meiosis halves chromosome number in gametes, fertilisation restores the full number, and how the new cell develops through mitosis and differentiation.
• Sexual vs Asexual Reproduction: Types and Advantages: Explore the key differences between sexual and asexual reproduction, examining the advantages of each type including variation production, energy efficiency, and survival benefits through natural selection.
• Reproduction Strategies in Nature: Investigate how different organisms use sexual and asexual reproduction strategies, including examples from parasites, fungi, and plants, and understand how organisms can switch between methods depending on circumstances.
• DNA Structure and the Genome
• Applications of Genome Research
• The Structure of DNA: Explore DNA as a polymer made from nucleotides, understanding the four bases (A, C, G, T) and how the sugar-phosphate backbone forms with bases attached. Learn about complementary base pairing and the overall structure of DNA strands.
• From DNA Code to Protein Synthesis: Understand how DNA sequences code for proteins, including the triplet code system where three bases code for one amino acid. Learn the basic process of protein synthesis and how DNA structure affects the proteins made.
• Genetic Variation and Mutations: Explore how genetic variants and mutations can influence phenotype through changes in coding and non-coding DNA. Understand how mutations affect protein structure and function, and how non-coding DNA regulates gene expression.
• Genetic vocabulary and basic inheritance (Part 1/2)
• Genetic vocabulary and basic inheritance (Part 2/2)
• Genetic crosses and Punnett squares
• Multiple gene inheritance
• Understanding Inherited Disorders: Explore how genetic disorders are passed from parents to offspring, including the difference between dominant and recessive inheritance patterns using polydactyly and cystic fibrosis as examples.
• Ethical Issues in Embryo Screening: Examine the economic, social and ethical considerations surrounding embryo screening for inherited disorders, developing skills to make informed judgements on these complex issues.
• Sex Chromosomes and Genetic Crosses: Students learn about human sex chromosomes (XX for females, XY for males), the 23 pairs of chromosomes in human cells including the sex-determining pair, and how to carry out genetic crosses to show sex inheritance using ratios and proportions.

Variation and evolution

• Causes of Variation: Explore how genetic factors, environmental conditions, and their combination create variation in organisms. Learn about genetic diversity in populations and how the genome interacts with environment to determine phenotype.
• Mutations and Phenotype Changes: Understand how mutations continuously occur and their effects on phenotype. Discover how rare beneficial mutations can lead to rapid evolutionary changes when they suit environmental conditions.

Cell division

• Chromosomes, DNA and Genes

The development of understanding of genetics and evolution

• Mendel's Revolutionary Discovery
• From Chromosomes to Gene Theory

Additional inheritance patterns

• Protein synthesis and gene variants: Understand how DNA sequences code for proteins, including the triplet code system where three bases code for one amino acid. Learn the basic process of protein synthesis and how DNA structure affects the proteins made.
• ABO blood groups and sex-linked inheritance: Cover codominance, multiple alleles and sex-linked inheritance explicitly for Edexcel Topic 3.

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More in this course

Go back to the full GCSE Edexcel Higher Biology topic list, or practise this topic with past-paper questions.