Cell Membrane Diagram Draw a diagram of the cell membrane. Please include (and label): - Phospholipid bilayer (hydrophilic and hydrophobic) Protein channel An ion pump Cholesterol Gylcoproteins* Define the function of each as it relates to the function of the membrane and cell (You will have some time on block day to work on this as well)
Block day 1. 2. 3. 4. 5. Grade quizzes Organelle partner quiz Finish cell membrane diagram Membrane transport notes * Transport and application in body
Cell Structure and Function Human cells share the common features of: 1. Plasma membrane 2. Cytoplasm 3. Nucleus structure Which all operate together to provide cellular functions.
The Plasma Membrane 1. Separates the extracellular and intracellular compartments of the body 2. Regulates the movement of materials between these compartments How does the plasma membrane relate to homeostasis?
Membrane Structure Equal amounts--by weight-- lipid and protein molecules, with a small amount of carbohydrates The lipid component Phospholipids Two parts HEAD=hydrophilic TAIL=hydrophobic Usually liquid and fluid Cholesterol Provide the stabilizing influence and increase the strength of the membrane
Membrane Structure Equal amounts--by weight-- lipid and protein molecules, with a small amount of carbohydrates The protein component Peripheral Attached to the outside and inside SURFACES Integral More numerous Have at least some portion WITHIN the membrane Most extend all the way through These would be channels for transport
Membrane Structure Equal amounts--by weight-- lipid and protein molecules, with a small amount of carbohydrates The carbohydrate component May be attached to the protein component and help in communication The two together would be GLYCOPROTEINS Serve as receptors to distinguish between the different cell types Think LABELS Hormones, growth factors, antibodies, etc.
Membrane Function Why is it necessary to regulate what enters and leaves a cell? The membrane is SELECTIVELY PERMEABLE Only some things can enter or leave Various transport mechanisms, grouped by the amount of energy needed 1. Passive processes 2. Active processes Which one uses energy? Which one does not use energy? What kind of energy?
Membrane Function Passive Processes 1. Diffusion Molecules move from an area of HIGH concentration to LOW concentration i. Try drawing a diagram of this in a way that makes sense to you Movement will continue until EQUILIBRIUM A difference in one concentration (amount) from one area to another is called a concentration gradient Examples? 2. Facilitated diffusion Same idea as diffusion but the molecules that are trying to move are too large to cross the membrane and need assistance Which molecules can help with this process?
Membrane Function Passive Processes 3. Osmosis: the movement of WATER molecules only, across the membrane Still from an area of high concentration to low concentration--but OF WATER! Water concentration = the amount of solutes present Many solutes = low water concentration Vice versa ISOTONIC SOLUTION: concentration of solutes is the same on both sides (of the barrier, membrane, etc.) HYPERTONIC SOLUTION: the solution on the outside has MORE solutes (high concen.) than whatever is in the solution HYPOTONIC SOLUTION: the solution on the outside has LESS solutes (low concen.) than whatever is in the solution EXAMPLE: a cell in a beaker of salt water...
Membrane Function Passive Processes 4. Filtration: movement of molecules from an area of high PRESSURE to low PRESSURE In the cell, small molecules are physically pushed through the plasma membrane by a pressure gradient EXAMPLE: in the kidneys, where blood pressure forces small molecules such as water, small ions and waste (urea) between the plasma membranes of the thin cells of the blood vessels and kidney tubules
Membrane Function Active Processes Use energy supplied by the cell In the form of.atp! Usually against the concentration gradient (from LOW concen. To HIGH concen.) Think UPHILL 1. Active Transport: requires ATP and integral proteins, called carriers Ex: Sodium-potassium pump in neurons Neurons need a concentration gradient in order to function
Membrane Function Active Processes
Membrane Function Active Processes 2. Cytosis: the transport of large volumes of materials and large particles across the plasma membrane Two types Endocytosis: INTO the cell (Think...ENTER) Exocytosis: OUT of the cell (Think...EXIT) This happens by extending part of the membrane around the material and enclosing it