BSC2085 Final Exam Study Guide You Should Be Able To Cumulative Portion Lesson 2 The Cell and the Plasma Membrane Explain the cell theory and who was crucial to its development Cell Theory Cells are the building blocks of all plants animals All cells form from the division of preexisting cells Cells are the smallest units that perform all vital physiological functions Each cell maintains homeostasis at the cellular level Cell theory was developed from Robert Hooke s research he viewed slices of cork under a light microscope coined the term cell Explain the difference between somatic and germ cells Sex cells are the cells used in reproduction sperm of males oocytes of females Somatic cells include all the other cells in the human body Describe the plasma membrane and explain its general functions Plasma Membrane The outer boundary of the cell Four 4 General Functions of the Plasma Membrane o 1 Physical isolation Physical barrier separating the inside of the cell from the outside o 2 Regulation of exchange with environment environment Can regulate Entry of ions nutrients Release of wastes cellular products by exocytosis o 3 Sensitivity to the environment Extracellular fluid composition can alter plasma membrane Can detect chemical signals through plasma receptors proteins o 4 Structural support Anchors cells and tissues to each other or to the extracellular matrix Provides stability to cells Describe the composition of the plasma membrane What are the different types of molecules that are found on it What are their functions The plasma membrane is composed of membrane lipids membrane proteins o Membrane Lipids largest component Phospholipid Bilayer Two layers of phospholipids Hydrophilic heads toward watery environments on both sides Hydrophobic fatty acid tails inside membrane away from water 1 BSC2085 Final Exam Study Guide You Should Be Able To Cumulative Portion Bilayer forms a barrier to ions water soluble compounds o Can t move past the hydrophobic lipid tails o Allows for interior of cell to have a different composition than the extracellular environment o Membrane Proteins 2nd largest component 55 of the weight of the membrane Integral Membrane Proteins Embedded within the membrane More numerous Transmembrane Proteins Traverse the width of the plasma Peripheral Membrane Proteins Bound to inner or outer surface of the membrane plasma membrane Receptor Proteins Bind and respond to ligands ions hormones Binding of the ligand can cause a change within the cell Carrier Proteins Transport specific solutes through membrane May may not require energy ATP Ex Glucose transport doesn t require energy but Na and Ca2 transport does Channels Integral proteins with a central pore Regulate water flow solutes through membrane Many channels are highly specific for a certain ion o Important in nerve impulse conduction muscle Anchoring Proteins Stabilize the cell contraction Attach to inside cytoskeletal or outside extracellular protein fibers or other cells structures Recognition Proteins Label cells as normal or abnormal Prevents immune system from reacting to the cell Many recognition proteins glycoproteins Enzymes Catalyze reactions inside or outside the cell May be integral or peripheral proteins Catalyze reactions inside or outside the cell Explain why the plasma membrane is a selectively permeable membrane The plasma membrane is selectively permeable so it can have control over what enters and leaves the cell To survive nutrients must be able to get in while wastes products must be able to get out It also allows the cell to bar unwanted chemicals from entering Describe the different types of transport Diffusion The net movement of a substance from an area of higher concentration to an area of lower concentration membrane o Simple Diffusion Materials diffuse through the phospholipid bilayer plasma Alcohol fatty acids lipid soluble drugs dissolved gases O2 CO2 2 BSC2085 Final Exam Study Guide You Should Be Able To Cumulative Portion o Channel Mediated Diffusion Diffusion through a channel in a transmembrane protein Leak Passive Channels Always open allow passage of ions in either Ions water soluble compounds direction in or out o Osmosis Diffusion of water across a cell membrane that is freely permeable to water selectively permeable to solutes from an area of higher H2O lower solute concentration to an area of lower H2O higher solute concentration Carrier Mediated Transport Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane o Cotransport Symport Carrier transports two substances in the same direction simultaneously in or out of the cell o Countertransport One substance moves into the cell and the other moves out o Facilitated Diffusion Molecule being transported binds to a receptor site on the carrier protein protein changes shape moving the molecule across the plasma membrane o Active Transport A high energy bond provides the energy needed to move ions Ion Pumps Carrier proteins that actively transport ions across the plasma Glucose amino acids or molecules across the membrane membrane Exchange Pumps Carrier proteins that move more than one kind of ion at the same time by countertransport in out of the cell o Secondary Active Transport Moves a specific substrate down its concentration gradient and can also move another substrate at the same time against its concentration gradient ATP needed later to preserve homeostasis What are the factors that affect the transport of substances Factors that affect the transport of substances include Size of the material molecule Electrical charge Molecular shape Lipid solubility Temperature Concentration gradient Interaction with channel Which types of transport utilize energy Energy Active Active transport Ion pumps Exchange pumps Secondary active transport Active or Passive Carrier mediated transport No Energy Passive Diffusion Simple diffusion Channel mediated diffusion Osmosis Facilitated diffusion 3 BSC2085 Final Exam Study Guide You Should Be Able To Cumulative Portion What is the difference between cotransport and countertransport In cotransport the carrier transports two substances in the same direction at the same time In countertransport the carrier transports one substance into the cell and another out of the cell What is the difference between active transport and secondary active transport Active transport requires energy from ATP to move ions or molecules across the membrane Secondary
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