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Unit 3: How do cells maintain life?

8 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

How do cellular processes work?

nucleic acids as information molecules that encode instructions for the synthesis of proteins: the structure of DNA, including nucleotide composition and the role of complementary base pairing, the three main forms of RNA (mRNA, tRNA, rRNA)

Nucleic acids. Covers nucleotide composition, the antiparallel double helix, complementary base pairing, and how mRNA, tRNA and rRNA differ in structure and role.

10 min read →

the role of enzymes and coenzymes in facilitating biochemical reactions, including factors affecting enzyme activity (temperature, pH, substrate concentration) and the effect of competitive and non-competitive inhibitors

Enzymes. Covers active site and induced fit, factors affecting rate (temperature, pH, substrate concentration), competitive vs non-competitive inhibition, and the role of coenzymes and cofactors.

11 min read →

the structure of genes including exons, introns and promoters and the role of regulator genes, including the role of the trp operon as an example of a regulatory process in prokaryotes

Gene structure and regulation. Covers exons, introns, promoters, regulator genes, and the trp operon as a worked prokaryotic example.

11 min read →

the expression of a gene to form a functional protein in a eukaryotic cell, including transcription, RNA processing (5' capping, polyadenylation and splicing) and translation, and the role of mRNA, tRNA and ribosomes

Gene expression. Covers transcription, the three RNA processing steps (5' cap, poly-A tail, splicing), and translation at the ribosome with mRNA and tRNA.

12 min read →

the inputs, outputs and locations of the light-dependent and light-independent stages of photosynthesis in plants (C3); the factors that affect the rate of photosynthesis; differences between C3, C4 and CAM plants

Photosynthesis. Covers the light-dependent reactions in the thylakoid (photolysis, ATP and NADPH), the Calvin cycle in the stroma (RuBisCO, G3P), factors that affect rate, and how C3, C4 and CAM plants differ.

13 min read →

the inputs, outputs and locations of glycolysis, the Krebs cycle and the electron transport chain in aerobic cellular respiration, and anaerobic fermentation in animal and plant cells

Cellular respiration. Covers glycolysis in the cytosol, the Krebs cycle in the mitochondrial matrix, oxidative phosphorylation at the inner mitochondrial membrane, and anaerobic respiration to lactate or ethanol.

13 min read →

amino acids as the monomers of a polypeptide chain and the resultant hierarchical levels of structure that give rise to a functional protein

Protein structure. Covers amino acids, the four levels of protein structure (primary, secondary, tertiary, quaternary) and the link between structure and function.

10 min read →

How do cells communicate?

the stimulus-response model and the role of signalling molecules, receptors and signal transduction in coordinating cellular responses, including the role of apoptosis as a regulated cellular response

Cell signalling and apoptosis. Covers the stimulus-response model, hydrophilic and hydrophobic signalling molecules, surface and intracellular receptors, signal transduction cascades, apoptosis versus necrosis, and the role of regulated cell death in development and disease.

12 min read →