LB145 Sec 001-004

1. LB145Sec 001-004

2. Today’s Outline • HAND IN StudyNotes– front of classroom. • Homework Assignment due on Tuesday. • Create a Classroom Code of Conduct. • Protein review. • Lipids + Membranes • A human experiment • Membrane transport

3. What is a protein?

4. What do proteins do?

5. Where do you get proteins from? • Discuss with your neighbor: • What are some foods that are high in protein content? • What are some foods that contain no protein?

6. What is a protein? • A protein is a chain of amino acids. • ALL foods contain proteins – because all living cells contain proteins. • When we eat proteins, our body breaks them down into their composite amino acids. We use these amino acids to make our own proteins.

7. A Chain of Amino Acids

8. Lipids

9. Clicker Question: What is a lipid? • Is a group of molecules that includes: fats, steroids and phospholipids. • Molecules that have fatty-acid side chains. • Carbon-containing compounds that are non-polar and hydrophobic. • A molecule with a hydrophilic head and a hydrophobic tail that is a major component in cell membranes.

10. Lipids • A lipid is an organic compound, found in organisms, that is primarily non-polar and hydrophobic. • Three types to know • Fats (triacylglycerol) • Phospholipids • Steroids Campbell 8e, Fig. 5.15 Campbell 8e, Fig. 5.13b

11. Fatty acids form ester bonds with glycerol

12. Fats consist of glycerol linked to three fatty acids

13. Biological Membranes are Composed of Phospholipids

14. Biological Membranes are Composed of Phospholipids Campbell 8e, Fig. 5.13

15. What is a Membrane? • A phospholipid bilayer (a fluid mosaic).

16. Membrane Fluidity The individual phospholipid molecules in lipid bilayer membranes are in constant motion Membranes are dynamic structures

17. Membrane Fluidity The Role of Steroids

18. Steroids Which is true? • Cholesterol reduces fluidity and reduces permeability of membranes. • Cholesterol increases fluidity and increases permeability of membranes. • Cholesterol increases fluidity and decreases permeability of membranes. • Cholesterol decreases fluidity and increases permeability of membranes.

19. Role of Cholesterol

20. Back to talking about things that have fatty acid side chains…

21. Saturated vs. Unsaturated(a fat question) Which of the following statements about unsaturated fat is true? • They are more common in animals than plants. • They have double bonds in the carbon chains of their fatty acids. • They generally solidify at room temperature. • They contain more hydrogen that saturated fats having the same number of carbon atoms. • They have fewer fatty acid molecules per fat molecule.

22. The Shape of Phospholipids… • Why is one leg of the phospholipid bent?

23. Saturated vs. Unsaturated

24. Membrane Permeability A human experiment…

28. Tonicity

30. Osmosis can cause the shrinking or swelling of cells

31. Building Mental Models • Think about a cell membrane – how would you draw one? Membrane? Membrane?

32. Proteins Cell exterior Phospholipid bilayer Cell interior

35. Transmembrane Proteins and Transport Transmembrane proteins are imperative for cellular transport. Channels Carrier proteins or transporters Pumps Passive facilitated processes Active facilitated process

36. Hydrophilic interior Outside cell Hydrophobic exterior H2O Inside cell

37. Gated Channels Potassium ions enter the channel Outside cell Inside cell Closed Positive charge triggers channel to open. Electrochemical gradient. Open

40. Active Transport by Pumps Molecules can be transported againstan electrochemical concentration gradient. This requires energy.

42. Summary of Membrane Transport Diffusion Small, non-polar, uncharged Facilitated diffusion Channel Protein Carrier Protein Active transport Requires Energy

44. Your HOMEWORK This homework is worth 5 points. Once you hand it in, you will be asked to evaluate someone else’s homework – the quality of your evaluation will be worth an additional 2 points. All point-determinations will be made by the teaching team. Instructions: - Use a word-processor (12 pt. font) for your responses. - You MUST upload a copy of your homework to the Angel TurnItInDropbox folder. - DO NOT INCLUDE YOUR NAME ON THIS ASSIGNMENT. - When you upload your assignment to the Angel TurnItInDropbox folder it should have no identifying marks. - When you bring a copy to hand in at class on January 15th (12:40pm), you should identify yourself using ONLY the last four digits of your PID #. If your name is on the assignment it will not be accepted. The Question: Compare and contrast simple diffusion, facilitated diffusion, and active transport across a biological lipid bilayer membrane. - Define each process as applied to a biological lipid bilayer membrane. - Provide a specific example of each process as applied to a biological lipid bilayer membrane. - Describe each example (what’s going on? how does it work?). REMEMBER – It’s OK to discuss ideas with friends, but YOU MUST TURN IN YOUR OWN UNIQUE WORK!!!

45. For Tuesday: • Homework #1 is due • Available on the website. • Be sure to follow instructions!! • TurnItIn + Paper Copy. • Register your clicker. • StudyNotes #2 is due onThursday. It’s a big one!7.0, 7.1, 7.2, 7.5