1. https://www.youtube.com/watch?v=5m8XN wLl798

2. https://www.youtube.com/watch?v=NSBaxVi dcqo

3. Do elephants and mice have the same size cells??

6.  Minimize diffusion time  No “donut holes”  No poking holes into cell  Done when 100% color gone  Disqualified if cell breaks apart  mass/time ratio identifies winner!

7.  Print out or draw a picture of your cell (color)  Include a typed description of the cell, its function, and how it has overcome the SA:V ratio problem.  This should be on a piece of cardstock or printer paper

8.  Erythrocytes, also known as red blood cells (RBCs), function to transport oxygen in the blood. The shape of erythrocytes is ideal for this function. Seen from the top, erythrocytes appear to be circular, but a side view shows that they are actually biconcaved discs. This shape increases the surface area-to-volume ratio of the cell, thus increasing the efficiency of diffusion of oxygen into and out of the cell.

14. Membranes and Membrane Transport

15.  Barrier  Gate Keeper  Communicator

16.  Lipids, proteins and carbohydrates…

21.  Surface carbohydrates Short, branched chains Cell-cell recognition Glycolipids glycoproteins

22. Integral: embedded in phospholipid layer for transport, carriers, and receptors may or may not be transmembrane Peripheral: found on inner or outer membrane surface act as point of attachment for cytoskeleton

23.  Cells must move materials through the membrane to maintain homeostasis.

27.  Lab: Osmosis and Diffusion

28.  - moves materials against a concentration gradient. - requires Energy (ATP).

29. Active Transport by membrane Proteins:  Globular proteins act as “ferries” for specific molecules  shape change allows transport from one side of membrane to other  called protein pumps

30. Many models & mechanisms--  uniports, symports, antiports  primary vs. secondary active transport

31.  The cell removes 3 sodium ions for every 2 potassium ions that enter the cell. This mechanism requires energy.

32. Example of Transport: Absorption of Nutrients in the small intestine  Passive transport Water, fatty acids, glyderol, some vitamins by diffusion  fructose by facilitated diffusion  Active (protein pumps) transport  amino acids, glucose, some vitamins  against concentration gradients across intestinal cell membranes  allows intestine to absorb much higher proportion of nutrients in the intestine than would be possible with passive diffusion  worth the cost of ATP!

33. Structure: Small Intestines  Absorption through villi& microvilli  increase surface area

34. Gated channels  Some channel proteins open only in presence of stimulus (signal)  stimulus usually different from transported molecule  ex:ion-gated channels: when neurotransmitters bind to a specific gated channels on a neuron, these channels open = allows Na+ ions to enter nerve cell  ex:voltage-gated channels - change in electrical charge across nerve cell membrane opens Na+& K+ channels