CHAPTER 2 Cells Cells Introduction The basic living structural and functional units of Cell biology Cells perform chemical reactions to create life the body processes Compartmentalization cells regulate things that go in and go out of the cell genetic material etc specialization A Generalized Cell Three Principal Parts 1 Plasma membrane 2 Cytoplasm 3 Nucleus Structure of Plasma Membrane Flexible yet sturdy barrier always things to go in and out Separates the internal from the external The fluid mosaic model the arrangement of molecules within the membrane resembles a sea of lipids containing many types of proteins The lipids act as a barrier to certain substances The proteins act as gatekeepers to certain molecules and ions Structure of a Membrane Consists of a lipid bilayer Integral proteins cross over both the layers of the lipid bilayer Transmembrane proteins Peripheral proteins do not cross the lipid bilayer are attached to either the inside or the outside Specific functions like contains enzymes that will help start reactions in the cell Also supports the plasma membrane Structure of the Plasma Membrane Functions of Membrane Proteins channels Some integral proteins act as cell identity markers are ion Transporters selectively moving substances throughout those channels Receptors for cellular recognition a ligand is a molecule that binds with a receptor Enzymes catalyze chemical reactions Others act as cell identity markers Ligand molecule that binds with the receptor Hyperplasia out of control cell growth b c of lack of communication Membrane Permeability The cell is either permeable let it in and out or impermeable don t let it in and out to certain substances Impermeable to glucose Glycoprotein Carbohydrate protein its attached to a protein and extends to the carbohydrate fluid Glycocalyx take all the carbohydrates they make up the glycocalyx that surround the membrane Acts as a cell identity marker Helps cells bind together when necessary Serves as a lubricant Transport Across the Plasma Membrane Intracellular fluid ICF fluid within the fluid Extracellular fluid ECF fluid outside the cell Interstitial fluid fluid in between the celll Plasma the extracellular fluid in blood vessels Lymph the extracellular fluid in the lymphatic cells Transport Interactions Animations Transport Across the Plasma Membrane You must be connected to the internet to run this animation Copyright 2012 John Wiley Sons Inc Transport Across the Plasma Membrane Locations of Various Fluids Intracellular fluid ICF Extracellular fluid ECF Interstitial fluid Plasma Lymph Passive vs Active Processes Passive processes substances can move across the cell membrane with energy they use kinetic energy Active processes uses energy from the breakdown of ATP Transport Across Plasma Membranes Kinetic energy transport Simple diffusion net movement of substance from high concentration to low concentration Osmosis movement of water across selectivelt permeable membrane Facilitated diffusion only occur when concentration gradient there rate of this movement depends on steepness diff of concentration gradient Simple diffusion net movement of substance from high concentration to low concentration Filtration process by which the kidneys function Active Transport Vesicle Endocytosis three types Receptor mediated endocytosis Phagocytosis ex White blood cell Bulk phase endocytosis pinocytosis cell drinking Exocytosis the vesicles fuse with the cell membrane and fluids go out into the cellular fluid Transcytosis the combination of endocytosis and exocytosis Copyright 2012 John Wiley Sons Inc Phagocytosis Clinical Connection Phagocytosis and microbe Phagocytosis Copyright 2012 John Wiley Sons Inc Cytoplasm Two Components Cytosol the fluid portion of the cytoplasm that surrounds organelles the intercellular fluid that surrounds it 75 95 water Site of a lot of chemical reactions in the cell energy being produced Organelles specialized structures with the cell have specific shape and functions network of protein filaments throughout the cell Microfilament support microvilli Intermediate filaments anchor the organelles Microtubules large and are composed of tubulins and are associated with flagellum and centrosome Organelles Cytoskeleton Copyright 2012 John Wiley Sons Inc Organelles Centrosome made up of two sets of centroles it also is surrounded by the pericentriolar material Each centrosome are made up of 9 clusters of microtubules 9 0 arrangement Play a role in cilia flagella and mitotic apparatus it is made of mitotic spindle and the spindles Cilia and flagella Cilia is used to move something short and hair like and Flagella is on sperm cells is longer and can move an entire move fluids cell The Centrosome Copyright 2012 John Wiley Sons Inc Cilia and Flagella Copyright 2012 John Wiley Sons Inc Clinical Connection Cilia and smoking The nicotine and the tar burn the cilia Organelles Ribosomes free ribosome are loose inside the cytosol Synthesis the proteins needed in the cell Attached ribosomes attach to the plasma membrane and synthesize the protein needed for the protein itself for export Endoplasmic reticulum a network of membranes of flattened sacks cisterns Rough ER attached to the nuclear envelope studded with ribosomes Smooth ER a network of tubules don t have ribosomes synthesis fatty acids and steroids detoxifies certain drugs Ribosomes Endoplasmic Reticulum Copyright 2012 John Wiley Sons Inc Organelles Golgi complex synthesis and send proteins when it exits it can become a secretory vesicle that carry proteins that exit the cell by exocytosis Membrane vesicle carries proteins carried by plasma membrane Can leave as a storage vesicle that will become a lysosome Lysosomes digests foreign substances Primary are entact but are enactive Secondary are actively breaking down Golgi Complex Copyright 2012 John Wiley Sons Inc Lysosomes Clinical Connection Tay Sachs inherited disease cause by faulty absent lysosomes therefore the digestive enzymes necessary for digestion are not present very fatal disease Organelles Peroxisomes smaller than lysosomes detoxify toxic substances such of alcohol Proteasomes they are active and removes damaged proteins found in the nucleus Organelles Mitochondria the powerhouses of the cell Cristae folds inside the membrane Matrix fluid inside the cavity Self replicate during times of increased cellular demand or before cell division Example of runner in class Mitochondria Double walled membrane