Prokaryotic and Eukaryotic cells

Prokaryotic and Eukaryotic cells

1. Cell cytoskeleton

   • The cytoplasm has a network of protein threads running through it this is called the cytoskeleton
   • In eukaryotic cells the protein threads are arranged as microfilaments and microtubules
   • Function
     • 1. The microtubules and microfilaments support the cells organelles keeping them in position
     • 2. They also help strengthen the cell and maintain its shape
     • 3. Responsible for movement of materials within the cell
     • 4. The proteins of the cytoskeleton can also cause cells to move

2. Organisms can have prokaryotic or eukaryotic cells

3. Plants and animals are both Eukaryotic - Eukaryotic cells are more complex

4. Organelles

   • Plasma cell surface membrane
     • Made of phospholipids and protein
     • It regulates the movement of substances into and out of the cell
   • Cell wall
     • Made of cellulose
     • Supports plant cells, prevents them from bursting
   • Nucleus
     • Nucleus contains chromatin and a nucleolus and is surrounded by a double membrane nuclear envelope
     • Controls cells activities, contains DNA - instructions to make proteins.
     • The pores allow substances to move between the nucleus and the cytoplasm
     • Nucleolus makes ribosomes
   • Lysosome
     • A round organelle surrounded by a membrane
     • Contains digestive enzymes - can digest invading cells or break down worn components of the cell
   • Ribosome
     • Very small organelle found in cytoplasm or attached to rough ER - made up of protein and RNA
     • Site where proteins are made
   • Rough endoplasmic reticulum
     • Surface covered with ribosomes
     • Folds and processes proteins that the ribosomes made
   • Smooth endoplasmic reticulum
     • Similar to rough ER but with no ribosomes
     • Synthesises and processes proteins
   • Vesicle
     • Small fluid filled sac in the cytoplasm surrounded by a membrane
     • Transports substances in and out of the cell and between organelles
   • Golgi apparatus
     • Group of fluid filled, membraned, flattened sacs - vesicles seen at the edges
     • Processes and packages new lipids and proteins and also makes lysosomes
   • Mitochondria
     • Double membrane - usually oval-sausage shaped
     • Site of aerobic respiration where ATP is produced
   • Chloroplast
     • Small flattened structure found in plant cells - surrounded by a double membrane
     • Where photosynthesis takes place
   • Centriole
     • Small hollow cylinders made of microtubules
     • Involved in separation of chromosomes in cell division
   • Cilia
     • Small hair like structure found on cell surface membrane to increase surface area - made of 9 pairs of microtubules and 2 in the middle
     • The microtubules allow the cilia to move - this movement is used by the cell to move substances along the cell surface
   • Flagellum
     • Like cilia but longer - stick out the cell surface - like cilia 9+2
     • Microtubules contract to make the flagellum move

5. Organelles in protein production

   • 1. Proteins made at ribosomes
   • 2. Ribosomes on rough ER make proteins that are excreted or attached to the cell membrane
   • 3. New proteins made at the rough ER are folded and processed in the rough ER
   • 4. Then theyre transported from the ER to the golgi apparatus in vesicles
   • 5. At the golgi apparatus the proteins may undergo further processing
   • 6. The proteins enter more vesicles and are transported around the cell

6. Prokaryotic cells

   • Bacteria cells are prokaryotic
     • Prokaryotes are the tenth of the size of eukaryotic cells
     • Microscopes arent good enough to see inside

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