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SingaporeBiology

Molecular Genetics

7 dot points across 7 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How do cells switch genes on and off so that the right proteins are made at the right time?

Explain the control of gene expression in prokaryotes (the lac operon) and the principles of eukaryotic gene control
A focused answer to the H2 Biology Molecular Genetics outcome on gene control. The lac operon as a model of prokaryotic regulation, transcription factors and chromatin in eukaryotes, and why differential gene expression underlies cell specialisation.
9 min answer →

How is the structure of DNA suited to storing genetic information and copying it accurately?

Describe the structure of DNA and explain the semi-conservative mechanism of DNA replication
A focused answer to the H2 Biology Molecular Genetics outcome on DNA. The double helix and complementary base pairing, the antiparallel strands, and the semi-conservative mechanism of replication using helicase, DNA polymerase and ligase.
9 min answer →

How do the tools of molecular biology let us copy, cut, join and analyse DNA, and what are these techniques used for?

Describe the principles of recombinant DNA technology, PCR, gel electrophoresis and DNA sequencing and outline their applications
A focused answer to the H2 Biology Molecular Genetics outcome on DNA technology. Restriction enzymes and ligase in recombinant DNA, the polymerase chain reaction, gel electrophoresis, DNA sequencing, and applications from insulin production to genetic profiling.
9 min answer →

How is the genetic material organised within a genome, and what can genomics tell us about an organism?

Describe how DNA is organised into chromosomes and genomes and outline the applications of genome sequencing
A focused answer to the H2 Biology Molecular Genetics outcome on genome organisation. Histones and chromosome packaging, coding and non-coding DNA, the difference between the genome and the proteome, and the applications of genome sequencing.
8 min answer →

What types of mutation occur in DNA, and how do they affect the protein produced and the organism?

Describe the types of gene and chromosome mutation and explain their effects on protein structure and phenotype
A focused answer to the H2 Biology Molecular Genetics outcome on mutations. Substitution, insertion and deletion; silent, missense, nonsense and frameshift effects; chromosome mutations; and how mutations drive variation, disease and resistance.
9 min answer →

What are the properties of the genetic code, and how do they shape the relationship between DNA and proteins?

Describe the genetic code and explain its key properties: it is a triplet code, degenerate, non-overlapping and near universal
A focused answer to the H2 Biology Molecular Genetics outcome on the genetic code. Codons and the triplet code, degeneracy, the non-overlapping and near-universal properties, start and stop codons, and why these properties matter for mutation and gene transfer.
8 min answer →

How is the information in a gene used to build a polypeptide through transcription and translation?

Describe the processes of transcription and translation and the roles of mRNA, tRNA and ribosomes in protein synthesis
A focused answer to the H2 Biology Molecular Genetics outcome on protein synthesis. Transcription of DNA into mRNA, RNA processing in eukaryotes, and translation at the ribosome with tRNA, including initiation, elongation and termination.
10 min answer →