Triglyceride ( fat or oil)

1. + - O -C-R'' O -C-R O -C-R' O -P-O-CH2-CH2-NR3+ O -C-R' O -C-R = = = = = = CH2-O CH-O CH2-O CH2-O CH-O CH2-O = O- Triglyceride (fat or oil) esters formed between alcohol (glycerol) and 3 fatty acids Phosphoglycerides Contain a phosphate ester. The phosphate also forms an ester with an amino alcohol. (e.g. ethanolamine R = H, choline R = CH3, or serine)

5. Triglyceride - Fatty acid storage – Primary energy reserve source for metabolism Cholesterol – a steroid - Moderates fluidity of animal cell membranes with DT. Lecithin (a phospholipid/phosphoglyceride) Primary membrane lipid component

7. Functions of Membrane Proteins Transport material - active or passive transporters or channels Signal Transduction – receptors (transport ‘message’) Catalysis in Nonpolar solvent combinations of the above

8. The type of amino acids likely to be found here are …….. a) nonpolar b) polar c) charged (acidic/basic) Transmembrane proteins typically have nonpolar, a-helical segments that pass through the lipid bilayer.

9. Which of the following molecules easily pass through the lipid bilayer without protein assistance? a) water b) sodium ions c) sugar molecules d) none of the above Proteins that assist in the transport of molecule across the membrane are … a) receptors b) transmembrane proteins c) both of the above d) none of the above

11. Aquaporins allow rapid water passage through membranes Although the tranmembranehelices typically have nonpolar side chains, polar or charged groups often line the pores through a ring of helices.

12. Membrane Rafts • contain ordered clusters of glycosphingolipids with longer-than-usual tails • allow segregation of proteins in the membrane Membrane surfaces are not all uniform

13. Protein content of Membranes Inner Mitochondria Red Blood Cell Myelin Sheath 80% Protein & 20% Lipid 50% Protein & 50% Lipid 20% Protein & 80% Lipid Cells have many different receptors, transporters, etc.

14. GLUCOSE TRANSPORTER • Muscle • passive • deployed - insulin • direction - one way “in” • Liver • passive • always present • direction: 2-way depends on equilibrium

15. Glucose Transporter in the Membrane

16. There are multiple glucose transporters • A Na+-glucose symporter and a glucose uniporter operate on opposite sides of epithelial cells • Cells can also have asymmetry, with distinct proteins confined to one side

17. I I Liver/Brain I Insulin secretion in response ↑ [glucose] in blood, leads to deployment of Glucose transporter in Muscle cells. Muscle This leads to a drop in [glucose] in the blood with a corresponding rise in The [glucose] in muscle cells. Represents the glucose transporter

18. Model for Glucose Transport

19. Lipoproteins good bad

20. Phospholipids cholesterol Apolipoprotein modules Triglycerides & cholesterol esters Lipoproteins

22. Chapter 11: Summary In this chapter, we learned: • membranes are composed of various lipids and proteins • phospholipids form a selectively permeable bilayer • properties of the bilayer depend on the lipid composition, which varies strongly from • organism to organism • tissue to tissue • organelle to organelle • membrane proteins play a variety of structural and functional roles, especially in the transport of solutes across the membrane • Active transport of solutes across membranes requires ATP but can be accomplished in many different ways