Cell Transport

Cell Cell- Smallest unit of life Analogy:

Barrier to Entry

Cell Membrane Functions: Encloses, protects, regulates entry to cell

Cell Membrane Properties: Selectively Permeable: allows certain molecules in and out Lipid Bilayer: two layers of lipids arranged in a certain way Polar versus Nonpolar: has both a charged and a non-charged region

Movement across the membrane Two types: Passive Mechanisms: Do not require cellular energy Active Mechanisms: require cellular energy in the form of ATP (adenosine triphosphate)

(Simple Diffusion) Passive Transport From high concentration to low concentration (across the concentration gradient) Examples:

Facilitated Diffusion Passive Transport Requires carrier protein Still from high concentration to low concentration Molecules are too big to move across the membrane

Osmosis Movement of water across a membrane The solute does not move across the membrane

Filtration Forcing molecules through a membrane (without energy) Examples:

Passive Mechanisms Write: What are the main differences between the four of these mechanisms? Share with a partner. How are you going to remember them?!

Active Transport REQUIRES ENERGY!

Active Transport Goes against the concentration gradient From lower concentration to higher concentration Requires ATP Utilizes carrier proteins Examples: Sugar, Amino acids… larger molecules

Endocytosis Molecules that are too large to enter, come in through a vesicle

Exocytosis Secreting substances via a vesicle to the outside of the cell

Active Mechanisms What are they? Differences between the different types? How are you going to remember them?

Concept Map time Step 1: Generate a list of the words that you think are important from what was presented today. Step 2: Sort them into categories For example: Endocytosis: phagocytosis, pinocytosis, receptor-mediated endocytosis Step 3: Connect- Organize the categories in boxes with arrows (so it looks like a concept map) Step 4: Elaborate- we will discuss our concept maps

Questions Which of the following processes includes all others? Osmosis Diffusion of a solute across a membrane Facilitated diffusion Passive Transport Transport of an ion down its gradient

Questions An artificial cell consisting of an aqueous solution enclosed in a selectively permeable membrane has just been immersed in a beaker containing a different solution. The membrane is permeable to water and to the simple sugars glucose and fructose but completely impermeable to the disaccharide sucrose. 1. Which solute(s) will exhibit a net diffusion into the cell? Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell”: 0.03 M sucrose 0.02 M glucose

Questions An artificial cell consisting of an aqueous solution enclosed in a selectively permeable membrane has just been immersed in a beaker containing a different solution. The membrane is permeable to water and to the simple sugars glucose and fructose but completely impermeable to the disaccharide sucrose. 2. Which solute(s) will exhibit a net diffusion out of the cell? Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell”: 0.03 M sucrose 0.02 M glucose

Questions An artificial cell consisting of an aqueous solution enclosed in a selectively permeable membrane has just been immersed in a beaker containing a different solution. The membrane is permeable to water and to the simple sugars glucose and fructose but completely impermeable to the disaccharide sucrose. 3. In which direction will there be a net osmotic movement of water? Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell”: 0.03 M sucrose 0.02 M glucose

Questions An artificial cell consisting of an aqueous solution enclosed in a selectively permeable membrane has just been immersed in a beaker containing a different solution. The membrane is permeable to water and to the simple sugars glucose and fructose but completely impermeable to the disaccharide sucrose. 4. After the cell is placed in the beaker, which of the following changes will occur? The artificial cell will become more loose (flaccid) The artificial cell will become more swollen (turgid) Some water molecules will flow into the cell, but the majority will flow out of it Despite the ability of sucrose to cross the membrane, eventually the two solutions will become isotonic Environment: 0.01 M sucrose 0.01 M glucose 0.01 M fructose “Cell”: 0.03 M sucrose 0.02 M glucose

Questions The concentration of a certain molecule inside and outside the plasma membrane of a cell was measured over time. The data are shown in the graph below. True statements about this molecule Include which of the following? This molecule is hydrophobic This molecule is necessary for cellular function This molecule required the expenditure of energy to enter the cell This molecule entered the cell using diffusion This molecule is embedded into the plasma membrane