Cell Biology and Organisation: Structure, Membranes and Division
Cell Biology and Organisation tests the relationship between cell structure, specialised function and levels of organisation. Expect organelle identification, comparison of plant, animal and prokaryotic cells, movement across membranes, and mitosis.
Cells and organelles
- Eukaryotic cells have a membrane-bound nucleus and organelles; prokaryotes lack a nucleus and membrane-bound organelles, have 70S ribosomes, circular DNA, plasmids, capsule and flagellum.
- Nucleus: chromosomes and nucleolus; rough ER transports proteins; smooth ER lipid synthesis; Golgi modifies, packages and secretes; mitochondria aerobic respiration; chloroplast photosynthesis; lysosomes hydrolysis; ribosomes protein synthesis.
- Plant cells: cellulose cell wall, chloroplasts, large permanent vacuole, no centrioles in higher plants. Animal cells: centrioles, small temporary vacuoles, no chloroplasts or cell wall.
- Plasma membrane is a phospholipid bilayer with proteins: selectively permeable; diffusion, osmosis, facilitated diffusion, active transport.
Organisation
Cells → tissues → organs → systems → organism. Specialisation: red blood cells no nucleus, many haemoglobin; sperm tail; root hair long projection; guard cells.
Worked example: A microscope image of a cell is 30 mm wide; actual width 15 µm. Magnification = image/actual = 30 mm/0.015 mm = 2000×. Convert units first.
Mitosis: prophase, metaphase, anaphase, telophase; produces genetically identical diploid cells for growth and repair. Traps: magnification is not resolution; chloroplasts not in root cells; cell wall is fully permeable, membrane selectively permeable; organelle is not organ; active transport uses ATP and can move against gradient.