Cấu trúc và chức năng tế bào (Basics)

	Cells structures and functions One or more per cell Spherical shape Denser than surrounding cytoplasm
		Chromosomes - Usually in the form of chromatin - Contains genetic information - Composed of DNA - Thicken for cellular division - Set number per species (i.e. 23 pairs for human)
		Nuclear membrane - Surrounds nucleus - Composed of two layers - Numerous openings for nuclear traffic
		Nucleolus - Spherical shape - Visible when cell is not dividing - Contains RNA for protein manufacture

---

	Collective term for cytosol and organelles contained within Colloidal suspension Cytosol mainly composed of water with free-floating molecules Viscosity constantly changes
		Centrioles - Paired cylindrical organelles near nucleus - Composed of nine tubes, each with three tubules - Involved in cellular division - Lie at right angles to each other
		Chloroplasts - A plastid usually found in plant cells - Contain green chlorophyll where photosynthesis takes place
		Cytoskeleton - Composed of microtubules - Supports cell and provides shape - Aids movement of materials in and out of cells
		Endoplasmic reticulum - Tubular network fused to nuclear membrane - Goes through cytoplasm onto cell membrane - Stores, separates, and serves as cell's transport system - Smooth type: lacks ribosomes - Rough type (pictured): ribosomes embedded in surface
		Golgi apparatus - Protein 'packaging plant' - A membrane structure found near nucleus - Composed of numerous layers forming a sac
		Lysosome - Digestive 'plant' for proteins, lipids, and carbohydrates - Transports undigested material to cell membrane for removal - Vary in shape depending on process being carried out - Cell breaks down if lysosome explodes
		Mitochondria - Second largest organelle with unique genetic structure - Double-layered outer membrane with inner folds called cristae - Energy-producing chemical reactions take place on cristae - Controls level of water and other materials in cell - Recycles and decomposes proteins, fats, and carbohydrates, and forms urea
		Ribosomes - Each cell contains thousands - Miniature 'protein factories' - Composes 25% of cell's mass - Stationary type: embedded in rough endoplasmic reticulum - Mobile type: injects proteins directly into cytoplasm
		Vacuoles - Membrane-bound sacs for storage, digestion, and waste removal - Contains water solution - Contractile vacuoles for water removal (in unicellular organisms)

---

		Cell wall - Most commonly found in plant cells - Controls turgity - Extracellular structure surrounding plasma membrane - Primary cell wall: extremely elastic - Secondary cell wall: forms around primary cell wall after growth is complete
		Plasma membrane - Outer membrane of cell that controls cellular traffic - Contains proteins (left, gray) that span through the membrane and allow passage of materials - Proteins are surrounded by a phospholipid bi-layer.