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Plasma Membrane

The membrane that surrounds cells and their organelles

QuestionAnswer
What does a cells plasma membrane consist of? A phospholipid bi-layer with proteins embedded throughout
What is a phospholipid bi-layer? A phospholipid bi-layer refers to a phosphate anion head which is polar/hydrophilic and 2 lipid tails which are non-polar/hydrophobic
What is a protein called that spans across the entire phospholipid bilayer plasma membrane? An intrinsic protein or an integral protein
What is a protein called that exists on the outer parts of the phospholipid bilayer plasma mebrane? An extrinsic protein or a peripheral protein
What is the name of the arrangement of the phospholipids and proteins within the plasma membrane? The Fluid Mosaic Model (referring to the fact that the phospholipids move about freely along the membrane in a fluid like fashion and the proteins are fixed with limited mobility, creating an intuitive image similar to a mosaic)
What is the difference between permeable and semipermeable? Semipermeable means only certain molecules are able to pass through (usually referring to a membrane) while permeable means anything can pass through
Is a cells plasma membrane permeable or semipermeable? Semipermeable
What kind of particles can easily pass through a cells plasma membrane? Small uncharged particles
What kind of particles cannot pass through a cells plasma membrane? Highly charged or very big particles (unless they are aided by something that spans the membrane such as a receptor protein)
What are the two ways in which molecules can pass through a membrane? Diffusion or facilitated transport
How can the rate of a molecules diffusion into the cell be measured? By comparing it to changes in that molecules gradient (gradient referring to the differences in concentrations on both sides of the membrane)
What does it mean to "increase" the gradient? To increase the gradient means to increase the difference in concentrations on both sides of the membrane
What does it mean when something "moves along it's gradient"? To move along the gradient is to move from high concentration to low concentration
What does it mean when something "moves against it's gradient"? To move against the gradient is to move from low concentration to high concentration
If a graph of the gradient vs the rate of a molecule to cross a membrane reaches a point where increasing the gradient no longer increases the rate of crossing, what does this signify? This signifies that the molecule is crossing via facilitated transport because there is a limiting factor in the form of something such as a protein/receptor
At the point on a facilitated diffusion graph where the curve levels out, what do you know about the protein/receptor that was assisting in crossing the membrane? You know that it has become saturated, meaning it is working at the maximum capacity and cannot work faster regardless of increases in the gradient
What is facilitated transport? Facilitated transport refers to the case where there is something assisting a molecule to cross the membrane along it's gradient (from high concentration to low concentration)
What is active transport? Active transport refers to the case where there is something assisting a molecule to cross the membrane against it's gradient (from low concentration to high concentration)
What is the difference between facilitated transport and active transport? Facilitated transport refers to the assisting of a molecule to cross a membrane along it's gradient while active transport refers to the assisting of a molecule to cross a membrane against it's gradient
Does Active Transport require energy and why or why not? Yes, Active Transport requires energy (ATP) because it opposes the natural flow of particles along their gradient
Does Facilitated Transport require energy and why or why not? No, Facilitated Transport does not require energy because it goes along with the natural flow particles along their gradient
What are the two types of carrier mediated transport systems? Active Transport and Facilitated Transport
Name which of the following that exhibits saturation kinetics: Active Transport or Facilitated Transport Both
What is the most popular protein receptor in the plasma membrane that uses Active Transport? Sodium Potassium ATPase pump
Name the two ways things can enter or exit a cell other than through carrier mediated transport systems Endocytosis and Exocytosis
What is endocytosis? Endocytosis is when the plasma membrane invaginates and breaks off in a fashion that allows things to enter the cell ("cytosis" can be remembered as "cell eating")
What is exocytosis? Exocytosis is when the plasma membrane invaginates and breaks off in a fashion that allows things to exit the cell ("cytosis" can be remembered as "cell eating")
What is phagocytosis? Phagocytosis is a special case of endocytosis which mainly occurs when white blood cells want to remove pathogens, bacteria, or debris
Summarize the process of phagocytosis. The cell eats something (usually a pathogen/bacteria), the thing eaten is then inside the cell surrounded by a small membrane bubble which is then fused with lysosomes that release their contents and digest everything in the bubble making a phagolysosome
How many phospholipid bi-layers surround the mitochondria (describe) 2: The inner membrane is arranged in shelf-like folds referred to as cristae
How many phospholipid bi-layers surround the nucleus (describe) 2: These two membranes have pores in them called nuclear pores
Created by: 1512sl