Things that make you go hmm….. Why do certain drugs/hormones only target certain cells? What can accelerate the movement of drugs into the cells?

Membranes and Transport

Cell Membrane is Selectively Permeable Can any molecule enter the cell?

Fluid Mosaic Model Mosaic of molecules & proteins: integral and peripheral Dynamic

PARTS OF THE CELL MEMBRANE Phospholipids: Protein Channels: Protein Cytoskeleton: Protein a-helixes and glycocalyx: Cholesterol:

Membrane Proteins

Passive Transport No energy required Types: Diffusion Osmosis Facilitated Diffusion

1. DIFFUSION http://www.wisc-online.com/objects/index_tj.asp?objID=AP1903 At net equilibrium, molecules are still moving to and from both sides

2. OSMOSIS Different Environments: A. Isotonic

Osmosis and the Marathon Runner A marathon runner, Haily, is concerned about dehydration during her race so she consumes a lot of water during her race. Haily is surprised when she is very dizzy at the end of her race. Explain why. Haily’s friend, Thomas read he should drink Gatorade during his race. He also experienced dizziness though too. Explain why. a dangerous but little-recognised condition called exercise-associated hyponatraemia (EAH). Sometimes called water intoxication, EAH is marked by a low blood sodium concentration and can cause the brain to swell, causing confusion, loss of consciousness and seizure. hyponatremia is a condition in which the body's stores of sodium are too low, and this condition can result from drinking extreme amounts of water. Hyponatremia can lead to confusion, lethargy, agitation, seizures, and in extreme cases, even death. Early symptoms are nonspecific and subtle and may include disorientation, nausea, or muscle cramps. The symptoms of hyponatremia may also mimic those of dehydration, so athletes experiencing these symptoms may be given more water to drink, further worsening the condition. Hyponatremia is only a danger when extremely high volumes of fluid are lost and replaced with water - for example, when athletes engage in vigorous activity for a protracted time (such as in marathons or triathlons), or when any strenuous physical activity is carried out in very hot temperatures. Hyponatremia "Runner's World" states that a very serious and sometimes deadly side effect of drinking too much is hyponatremia. Hyponatremia is an over-hydration of the cells which causes dangerously low sodium levels in the body. Although hyponatremia usually occurs when an athlete drinks too much water, "Runner's World" states that it can occur if an athlete drinks too much Gatorade as well. Many athletes feel that they are doing a good thing by re-hydrating with Gatorade, so they think more is better, but in reality, too much Gatorade could be dangerous. There are 56g of sugar in each regular sized bottle of Gatorade, according to the Calorie King website. Though replacing some sugars lost during exercise is generally a good idea, drinking too much sugar can lead to high blood sugar in the cells which can be very dangerous. Since every person is different, there is no one amount of sugar which is too much to consume for everybody. Some people, such as diabetics, may get high blood sugar from drinking even half of a bottle of Gatorade, while it may take several bottles to cause high blood sugar in others Read more: http://www.livestrong.com/article/68710-effects-much-gatorade/#ixzz258moh34f

PLANTS VS. ANIMALS

3. Facilitated Diffusion E.g. glucose Still involves movement from high concentration to low concentration

Channel Protein – hydrophilic pathway Increases flow of larger solutes that would normally take so much longer to pass through bilayer Channel Protein – hydrophilic pathway Carrier Protein – binds to a specific solute, changes conformation

Active Transport

1. Protein Channels Sodium Potassium Pump Stock pile nutrients against the concentration gradient E.g. nerve cells need it like this to maintain inactive Controls conditions in the stomach

2. Endocytosis

2. a. Phagocytosis

2. b. Pinocytosis Pinocytosis is primarily used for the absorption of extracellular fluids generating small vesicles.

2. c. Receptor-mediated endocytosis (RME) Molecule binds to special receptor proteins located on outside of cell membrane

LDL import to the cell When a cell requires cholesterol, it synthesises the necessary LDL receptors, and inserts them into the plasma membrane LDL particles in the blood stream bind to these extracellular LDL receptors

Exocytosis Opposite of endocytosis and is used to transport large molecules out of the cell Like endocytosis, requires energy from ATP breakdown eg. insulin is produced in pancreatic cells, travels to rest of body by exocytosis eg. digestive enzymes, produced in cells of intestinal lining, are released into interior of intestine by exocytosis