* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Anatomy of a cell
Survey
Document related concepts
Biochemical switches in the cell cycle wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell growth wikipedia , lookup
Cell nucleus wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Anatomy of a cell Chapter 3 Typical Cell Cells vary due to function. The typical cell exhibits the most important characteristics of many distinctive cell types. Examples of cell types: Nerve cells, muscle cells, red blood cells, gland cells, and immune cells Functional Anatomy of Cells Cell structures Plasma membrane—separates the cell from its surrounding environment Cytoplasm—thick gel-like substance inside of the cell composed of numerous organelles suspended in watery cytosol; each type of organelle is suited to perform particular functions Nucleus—large membranous structure near the center of the cell Cell Membranes Each cell contains a variety of membranes: Plasma membrane Membranous organelles—sacs and canals made of the same material as the plasma membrane Cell Membranes Fluid mosaic model—theory explaining how cell membranes are constructed Molecules of the cell membrane are arranged in a sheet The mosaic of molecules is fluid; that is, the molecules are able to float around slowly This model illustrates that the molecules of the cell membrane form a continuous sheet Cell Membranes Primary structure of a cell membrane is a double layer of phospholipid molecules Heads are hydrophilic (water-loving) Tails are hydrophobic (water-fearing) Molecules arrange themselves in bilayers in water Cholesterol molecules are scattered among the phospholipids to allow the membrane to function properly at body temperature Most of the bilayer is hydrophobic; therefore water or watersoluble molecules do not pass through easily Plasma Membranes and Proteins A cell controls what moves through any section of membrane by means of proteins embedded in the phospholipid bilayer. The protein acts as a gate allowing watersoluble molecules to pass through the membrane. Cytoplasm and Organelles Cytoplasm—gel-like internal substance of cells that includes many organelles suspended in watery intracellular fluid called cytosol Cytoplasm and Organelles Two major groups of organelles: Membranous organelles are specialized sacs or canals made of cell membranes Nonmembranous organelles are made of microscopic filaments or other nonmembranous materials Organelles Endoplasmic reticulum (Highway system of the cell) Made of canals with membranous walls and flat, curving sacs arranged in parallel rows throughout the cytoplasm; extend from the plasma membrane to the nucleus Proteins move through the canals ER Two types of ER: 1) Rough ER: Ribosomes on the outer surface of the organelle 2) Smooth ER: Synthesizes certain lipids and carbohydrates and creates membranes for use throughout cell nonmembranous structure Ribosomes in the endoplasmic reticulum make proteins for “export” or to be embedded in the plasma membrane; free ribosomes make proteins for the cell’s domestic use Golgi apparatus Golgi apparatus (UPS of cell): flat-like pancake organelle that packages and delivers proteins and other organic molecules throughout the cell. Lysosomes Lysosomes (miniature stomach)- enzymes in lysosomes digest the protein structures of defective cell parts, including plasma membrane proteins, and particles that have become trapped in the cell Mitochondria Mitochondria (power plant of cell)mitochondrial enzymes catalyze series of oxidation reactions that provide about 95% of cell’s energy supply Each mitochondrion has a DNA molecule, allowing it to produce its own enzymes and replicate copies of itself Nucleus Consists of nuclear envelope (composed of two membranes each with essentially the same molecular structure as plasma membrane) surrounding nucleoplasm; nuclear envelope has holes called nuclear pores Cytoskeleton The cell’s internal supporting framework made up of rigid, rodlike pieces that provide support and allow movement and mechanisms that can move the cell or its parts (Figure 3-13) Centrosome An area of the cytoplasm near the nucleus that coordinates the building and breaking of microtubules in the cell- Important in cell division