Changes

[[Image:Plant_cell.png|center||Plant cell: The cell wall vs the cell membrane found in animal cells.]]

[[Image:Plant_cell.png|center||Plant cell: The cell wall vs the cell membrane found in animal cells.]]

Eukaryotes have a cytoskeleton, which is composed of a number of interacting fibre types. The first are the actin microfilaments, which, with the motor protein myosin, form the muscles of the cytoskeleton (and in sarcosomes, form actual muscles too). The actin cytoskeleton forms a cortex beneath the plasmalemma of most eukaryotic cells, which is involved in changes to the external shape of the cell (such as the formation of pseudopodia in amoebae).The second fibre type are intermediate filaments, composed of spectrin, keratin, vimentin, nuclear lamins and other proteins. The intermediate filaments help maintain the relative positions of organelles and give the cell mechanical strength. The third type of cytoskeletal filament are the microtubules, which form the spindle during cell divisions (meiosis and mitosis), and give structure to the cell membrane, forming microvilli. They also form undulipodia, which are waving structures with a typical 9+2 structure, found in cilia (short undulipodia) and flagella (longer ones). The microtubules are composed of tubulin, and are organised by a microtubule organising centre (the centrosome and centrioles in animals), in which the − ends of the microtubules (which grow more slowly than the + ends) are embedded. Vesicles traffic along the microtubules under the influence of motor proteins such as kinesin (which transports items from the −→+ ends, i.e. away from the MTOC) and dynein (which traffics items from +→−). Tubulin is homologous to the FtsZ protein that is involved in bacterial fission.

Eukaryotes have a cytoskeleton, which is composed of a number of interacting fibre types. The first are the actin microfilaments, which, with the motor protein myosin, form the muscles of the cytoskeleton (and in sarcosomes, form actual muscles too). The actin cytoskeleton forms a cortex beneath the plasmalemma of most eukaryotic cells, which is involved in changes to the external shape of the cell (such as the formation of pseudopodia in [[amoebas]]).The second fibre type are intermediate filaments, composed of spectrin, keratin, vimentin, nuclear lamins and other proteins. The intermediate filaments help maintain the relative positions of organelles and give the cell mechanical strength. The third type of cytoskeletal filament are the microtubules, which form the spindle during cell divisions (meiosis and mitosis), and give structure to the cell membrane, forming microvilli. They also form undulipodia, which are waving structures with a typical 9+2 structure, found in cilia (short undulipodia) and flagella (longer ones). The microtubules are composed of tubulin, and are organised by a microtubule organising centre (the centrosome and centrioles in animals), in which the − ends of the microtubules (which grow more slowly than the + ends) are embedded. Vesicles traffic along the microtubules under the influence of motor proteins such as kinesin (which transports items from the −→+ ends, i.e. away from the MTOC) and dynein (which traffics items from +→−). Tubulin is homologous to the FtsZ protein that is involved in bacterial fission.

The body of the cell is composed of a heterogeneous mixture of proteins and solutes called the cytosol. The cytosol contains many 80S ribosomes, on which protein synthesis takes place.

The body of the cell is composed of a heterogeneous mixture of proteins and solutes called the cytosol. The cytosol contains many 80S ribosomes, on which protein synthesis takes place.