Cell Biology orCytology Cyto = cell ology = study Uses observations from several types of microscopes to create a total picture of how a cell is put together.
The Plasma Membrane • Separates the cell from the environment. • Is “semi-permeable” and regulates the movement of materials in/out of a cell. • ALL cells have a plasma membrane.
The Fluid Mosaic Model The individual phospholipids are constantly shifting back and forth creating small openings….. The motion of these “shifting” lipids is referred to as a “fluid” motion.
In addition to the phospholipids, the plasma membrane contains: • proteins, • cholesterol, • and carbohydrates. Together they make up the “mosaic” portion of the “fluid mosaic” model.
The Membrane has several Protein “Groups” • Peripheral Proteins - are attached loosely to the inner or outer membrane. • Integral Proteins – extend into, or through the membrane. • Transmembrane Proteins – appear at both the inner and outer surface.
The Proteins, found in the Plasma Membrane, have several functions…. They are: • Channel Proteins • Transport Proteins • Recognition Proteins • Adhesion Proteins • Receptor Proteins • Electron Transfer Proteins
Channel Proteinsare passageways for certain substances through the plasma membrane
Transport Proteins use energy (ATP) to transfer materials across the membrane
Recognition Proteinsdistinguish the identity of neighboring cells. • are also called “glycoproteins” because they have short sugar or carbohydrate chains attached. • the sugar chains stick out from the surface like antennae. Glycoproteins
Adhesion Proteins • attach cells to other cells or • provide anchors for filaments
Receptor Proteins • act as binding sites for hormones or other trigger molecules
Electron Transfer Proteins • are involved in transferring electrons from one molecule to another during chemical reactions
Glycocalyx • is a carbohydrate “coat” covering the outer face of the plasma membrane…. • the glycocalyx provides recognition markers for cell to cell recognition
Organelle • is a term meaning "small organ”. • is a part or body in a cell with a specialized function. • is an important organizational structure of cells.
Organelles • are a way to form compartments in cells to separate chemical reactions. • they keep various enzymes separated in space. • In other words, they are bags of enzymes!
Cytoplasm is an Area (not stuff) between the cell membrane and the nuclear envelope. It contains the cytosol, and nucleus and cell organelles (if it’s a eukyote).
Cytosol • is the Semi-fluid portion of the cytoplasm (the gooey stuff inside the cell)…. • It is composed mostly of water and nutrients.