Cells (Unity and diversity)
- Origins of cellsHL only
- Early Earth HL only
- No O₂, no ozone
- UV reached surface
- High CO₂ and CH₄
- Miller–Urey HL only
- CH₄, NH₃, H₂, H₂O
- Sparks as lightning
- Amino acids formed
- Monomers only
- Living versus non-living HL only
- Cells: self-sustaining units
- Viruses non-living
- First cell requirements HL only
- Catalysis
- Self-replication
- Self-assembly
- Compartmentalisation
- Vesicles and RNA HL only
- Fatty acid bilayer spheres
- RNA: genes and enzymes
- Ribozyme forms peptide bonds
- LUCA HL only
- Universal genetic code
- Shared genes
- Hydrothermal vents
- About 4 billion years
- Early Earth HL only
- Cell structure
- Cell theory
- Organisms made of cells
- DNA, cytoplasm, membrane
- Unicellular: all eight functions
- Microscopy skills
- Mounts and stains
- Graticule calibration
- M = image ÷ actual
- Draw and annotate micrographs
- Developments in microscopy
- Electron microscopes: resolution
- Freeze fracture
- Cryo-EM
- Immunofluorescence
- Prokaryotes
- Peptidoglycan cell wall
- Naked DNA loop
- 70S ribosomes
- Bacillus, Staphylococcus
- Eukaryotes
- Nucleus with pores
- 80S ribosomes
- Membrane-bound organelles
- Cytoskeleton
- Eukaryote diversity
- Cellulose or chitin walls
- Vacuoles, plastids, centrioles
- Atypical: many or no nuclei
- Endosymbiosis HL only
- Mitochondria first
- Chloroplasts later
- 70S ribosomes, circular DNA
- Differentiation and multicellularity HL only
- Gene expression patterns
- Evolved repeatedly
- Size and specialisation
- Cell theory
- VirusesHL only
- Common features HL only
- Small, fixed size
- DNA or RNA
- Protein capsid
- No cytoplasm, few enzymes
- Diversity HL only
- Lambda: dsDNA, tailed
- Coronavirus: RNA, enveloped
- HIV: RNA, reverse transcriptase
- Lytic cycle HL only
- Attach and inject
- Host makes viral parts
- Assemble, lyse, release
- Lysogenic cycle HL only
- Prophage in chromosome
- Copied at division
- Induction to lytic
- Origins HL only
- Several origins
- Convergent evolution
- Shared genetic code
- Rapid evolution HL only
- High mutation rate
- Influenza: antigenic drift
- HIV: drug resistance
- Common features HL only