This is Chapter 1 – DNA & Proteins for the Year 12 Biology course.

This chapter takes students into the molecular foundations of life, examining how genetic information is stored, copied, expressed and altered. It builds on the basic DNA knowledge developed in earlier Biology courses, but introduces a much greater level of detail and requires students to connect molecular structures with their biological consequences.

We begin by comparing the organisation of DNA in prokaryotic and eukaryotic cells, including the role of histone proteins in packaging genetic material. Students then examine the structure of nucleotides and the weak hydrogen bonds that allow DNA to separate and replicate through a semi-conservative process.

Protein synthesis brings together DNA, messenger RNA, transfer RNA and ribosomal RNA through transcription and translation. Students will transcribe and translate genetic sequences using codon tables before investigating how an amino acid sequence determines the final three-dimensional structure of a protein. Enzymes provide an important example of the close relationship between structure, specificity and biological function.

Epigenetics introduces the idea that gene expression can change without altering the underlying DNA sequence. Students explore how DNA methylation, histone modification and environmental factors can affect gene activity, the cell cycle and an organism’s characteristics. Mutations are also examined in detail, including their causes, different forms and possible consequences for individuals and future generations.

The chapter concludes with DNA technology and biotechnology. Students investigate PCR, gel electrophoresis, DNA profiling, restriction enzymes and CRISPR-Cas9 while considering their applications and ethical, social and economic implications.

These ideas are central to medicine, genetics, biotechnology, forensic science, agriculture and biomedical research.

Subtopics:

• A: DNA Structure and Replication

• B: Protein Synthesis and Structure
• C: Enzymes
• D: Epigenetics
• E: Mutations
• F: DNA Technology
• G: Biotechnology

By the end of this topic, students will be able to explain DNA replication and gene expression, connect protein structure with function, and evaluate how mutation, epigenetics and biotechnology affect organisms and society.