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Membranes
C483 Spring 2013
Trans fatty acids have physical properties like those ofA) w-3 fatty acids.B) cis-fatty acids.C) unsaturated fatty acids.D) saturated fatty acids.
Triacylglycerols are not found in cell membranes because they are A) amphipathic.B) not amphipathic.C) not abundant in cells.D) charged at biological pH.
Glycerophospholipids have ________ heads and long ________ fatty acid tails.A) polar; polarB) polar; hydrophobicC) hydrophobic; polarD) hydrophobic; hydrophobic
Which type of membrane protein might be dissociated from the membrane by changing the pH or the ionic strength? A) Integral membrane protein.B) Lipid-anchored membrane protein. C) Peripheral membrane protein.D) All of the above.
Which can serve as an energy source for secondary active transport? A) Ion concentration gradient. B) Light. C) Electron transport. D) ATP → ADP
Lipids and Membranes
• There is a lot of important biochemistry of lipids.
• We won’t cover it all!• The key points for this class have to do with
their role in membranes and fat metabolism
Overview
• Read chapter 9, sections 1-4, 6, 8-10– Section 9.11 is important in discussion
• Major topics– Metabolism: fatty acids and triacylglyderieds– Membrane components: phosphoglycerides and
steroids– Membrane structure and dynamics– Membrane function: transport
Diversity
Fatty Acids
• Saturated• Unsaturated• Polyunsaturated• Cis and trans
Triacylglyderides
Phosphoglycerides
• aka glycerophospholipids• Polar head, hydrophobic tail
Diversity
Phospholipases
• Wide variety of phosphoglycerides
• Processed by range of lipases
• Snake venom
Steroids
• Structural similarity, functional diversity
Membranes
• Complex• Fluid• Dynamic• Compartment-
alization• Communication• Gradients
Lipid Bilayer
Dynamic
Fluid Mosaic
• Glycoproteins, proteins• Affect of cholesterol
Integral Membrane Proteins
Lipid anchored membrane proteins
Membrane Transport
• No thermodynamics for now• Pores and channels• Selective permeability• Sets up gradients
Types of Transport
• Passive Transport—with concentration or charge gradient– Diffusion across membrane– Facilitated diffusion
• Active Transport—goes against concentration or charge gradient– Requires energy input– Always facilitated
Facilitated Transport
Types of Transport
• Both passive and active transport can be– Uniport– Symport– Antiport
Primary and Secondary Transport
Answers
1. D2. B3. B4. C5. A