BRAINCAKEEukaryotic Cells
Revision notes for Eukaryotic Cells in Edexcel Biology (8BI0). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Magnification and ResolutionTwo ideas describe how well a microscope shows a specimen: magnification and resolution.
- Light MicroscopeThe light microscope (optical microscope) uses visible light focused by glass lenses.
- Electron MicroscopeAn electron microscope uses a beam of electrons instead of light.
- Transmission Electron MicroscopeIn a transmission electron microscope (TEM), a beam of electrons is passed through a very thin specimen.
- Scanning Electron MicroscopeIn a scanning electron microscope (SEM), a fine beam of electrons is scanned back and forth across the surface of a specimen.
- UltrastructureThe ultrastructure of a cell is the detailed internal structure that can only be seen with an electron microscope.
- MembranesEvery cell is surrounded by a cell surface membrane (plasma membrane), and in eukaryotic cells membranes also surround and form many organelles.
- Phospholipid BilayerThe basic structure of every membrane is a phospholipid bilayer.
- Membrane ProteinsProteins make up a large part of every membrane and carry out most of its specific jobs.
- Fluid Mosaic ModelThe fluid mosaic model, proposed by Singer and Nicolson in 1972, describes the structure of all cell membranes.
- Eukaryotic CellsEukaryotic cells are cells whose DNA is contained in a nucleus surrounded by a nuclear envelope.
- ProtoplasmProtoplasm is the living material of a cell: everything inside the cell surface membrane.
- The NucleusThe nucleus is usually the largest organelle in a eukaryotic cell, about 10 µm across.
- MitochondriaMitochondria (singular: mitochondrion) are the sites of aerobic respiration, where most of a cell's ATP is made.
- CentriolesCentrioles are small, hollow cylinders found in animal cells, usually in a pair lying at right angles to each other near the nucleus.
- CytoskeletonThe cytoskeleton is a network of protein fibres running through the cytoplasm of eukaryotic cells.
- VacuolesA vacuole is a sac in the cytoplasm surrounded by a single membrane and filled with fluid.
- RibosomesRibosomes are the sites of protein synthesis.
- Rough ERThe rough endoplasmic reticulum (RER) is a system of flattened, membrane-bound sacs called cisternae, whose outer surface is covered with ribosomes.
- Smooth ERThe smooth endoplasmic reticulum (SER) is a network of membrane-bound sacs and tubes like the rough ER, but without ribosomes on its surface.
- Golgi ApparatusThe Golgi apparatus (Golgi body) is a stack of flattened, curved, membrane-bound sacs called cisternae, with many small vesicles around its edges.
- LysosomesLysosomes are small, spherical vesicles surrounded by a single membrane and containing powerful hydrolytic enzymes (hydrolases), such as proteases…
- Plant CellsPlant cells are eukaryotic cells.
- Plant Cell WallsThe plant cell wall is a strong, non-living layer outside the cell surface membrane.
- PlasmodesmataPlasmodesmata (singular: plasmodesma) are very fine channels that pass through the cell walls of neighbouring plant cells, linking their cytoplasm.
- Permanent VacuoleMost mature plant cells contain a single large permanent vacuole, which may take up most of the volume of the cell.
- ChloroplastsChloroplasts are the organelles in which photosynthesis takes place.
- Organisation of CellsIn multicellular organisms, cells are organised into levels of increasing complexity: specialised cells → tissues → organs → organ systems →…
- Epithelial CellsEpithelial tissue (epithelium) covers the outer surfaces of the body and lines internal surfaces such as blood vessels, airways and the gut.
- Organ SystemsAn organ system is a group of organs that work together to carry out a major function in the body.