1.1. Plasma Membrane-forms outer boundary of cell, composed of thin, two- layered membrane of phospholipids containing proteins. Is selectively permeable.
1.2. Organelles-specialized structures within the cytoplasm.
1.3. Cytoplasm- living material inside of a cell. Contains organelles, and fills the space between the plasma membrane and the nucleus.
2. Organelles
2.1. Ribosomes-made up of two tiny subunits of mostly ribosomal RNA. Often called "Protein Factories" Manufactors enzymes and other protien compounds.
2.2. Endoplasmic Reticulum (ER)- network of connecting sacs and canals that carry substances through fluid cytoplasm. TWO TYPES: Rough ER- collects, folds, and transports proteins made ny ribosomes. Smooth ER- synthesizes chemicals; makes new membrane.
2.3. Golgi Apparatus- group of flattened sacs near the nucleus, collects chemicals into vessels that move from the smooth ER outward toward the plasma membrane. Called the "chemical processing and packaging center"
2.4. Mitochondria-contains one DNA molecule, involved in energy releasing chemical reactions. Called the " Powerhouse of the cell"
2.5. Lysosomes- contains digestive enzymes the can digest food and substances that invade the cell. Have a protective function (eating microbes) . Formerly thought to be responsible for apoptosis.
2.6. Centrosome- region of cytoplasm near nucleus. serves as microtubule-organizing center of cell. Function is cell reproduction.. cell division. Centrioles are found here.
3. Shape
3.1. Flat
3.2. Brick shaped
3.3. Threadlike
3.4. Irregular
4. Size
4.1. All cells are Microscopic.
4.2. Human cells vary considerably in size.
5. Cell Extensions
5.1. Microvilli- small, fingerlike extensions of the plasma membrane. They increase the absorptive surface area of the cell.
5.2. Cilia- fine hairlike extensions found on free or exposed surfaces of some cells capable moving in unison in a wavelike fashion.
5.3. Flagella- single projections extending from cell surface. much larger than cilia. Tails of sperm cells is the only example of flagella in humans.
