Cell Structures and Organelles

Cell Theory 1) All living things are composed of cells. 2) Cells are the basic units of structure and function in living things 3) New cells are produced only from pre existing cells.

Prokaryotes vs Eukaryotes Prokaryotes Have cell membranes and cytoplasm but no nuclei and membrane bound organelles. Examples: all bacteria Escherichia coli( E-coli) & Staphylococcus (Staph infection) Eukaryotes Have nuclei and membrane bound organelles. Examples: all plants, animals, and fungi.

Cytoplasm and Cytoskeleton Cytoplasm: the semifluid material inside the plasma membrane. Cytoskeleton: supporting network of long, thin protein fibers, that form a framework for the cell.

Nucleus Cell's managing structure. Directs cell processes. Contains most of the cell's DNA. Surrounded by a double membrane called the nuclear envelope.

Ribosomes Site of protein synthesis. Made up of RNA and protein. Ribosomes are produced inside the nucleus at the nucleolus.

Endoplasmic Reticulum Membrane system of folded sacs that serve as the site for protein and lipid synthesis. Can be smooth or rough.  Smooth: there are no ribosomes attached; complex carbohydrates and lipids are synthesized here.  Rough: ribosomes attached; produce proteins that will be exported to other cells.

Golgi Apparatus Flattened stack of membranes that modifies, sorts, and packages proteins into sacs called vesicles. These vesicles can then fuse with the plasma membrane to release proteins to the outside of the cell.

Vacuoles Sac used to store food, enzymes, and other materials needed by a cell. Some vacuoles store waste products. Animal cells and plant cells contain vacuoles.

Lysosomes Vesicles that contain substances that digest excess or worn-out organelles and food particles. They also digest bacteria and viruses that enter the cell. Why do the digestive enzymes inside a lysosome not destroy the cell?

Centrioles Organelles made of microtubles that function during cell division. They are located in the cytoplasm of animal cells and are usually near the nucleus.

Mitochondria Organelle that converts food particles (mainly sugar) into usable energy. Mitochondria have an outer membrane and a highly folded inner membrane that provides a large surface area for breaking the bonds in sugar molecules.

Chloroplasts Organelles that capture light energy and convert it to chemical energy through photosynthesis. The inner membrane of chloroplasts are small disk shaped compartments called thylakoids. Thylakoids contain chlorophyll that traps sunlight and gives leaves and stems their green color.

Cell Wall Thick, rigid mesh of fibers that surround that outside of the plasma membrane that protects the cell and gives it support. Only found in plant cells. Made of cellulose which gives it its inflexible characteristics.

Cilia Short projections that look like hair. Motion of cilia is simlar to the oars of a rowboat. Help in the movement of substances outside the cell.

Flagella Longer and less numerous than cilia. Cilia and flagella are composed of microtubles. Aide in movement of the cell.