This achievement standard involves the description of the role DNA has in relation to gene expression and the determination of phenotype.

The role of DNA includes DNA structure and replication, the control of gene expression, protein synthesis, and the determination of phenotype.

The structure of DNA includes the molecular components and their role in carrying the genetic code. The replication of DNA includes the processes involved in replication and the role that enzymes have in producing accurate copies.

Control of gene expression is limited to factors that operate at transcription level:

• feedback in prokaryotes (repressors, inducers)
• enhancers and transcription factors in eukaryotes.

Protein synthesis includes the role of DNA in determining the structure of a protein and how that protein is produced (transcription and translation).

The determination of phenotype includes:

• allele interactions: dominance, incomplete dominance, co-dominance, multiple alleles, lethal alleles
• linkage and sex linkage
• gene-gene interactions: epistasis, collaboration, polygenes
• pleiotropy
• mutations: gene mutations, chromosomal mutations
• control of metabolic pathways by gene expression.