BioChem: Lipids and Membranes
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What is able to easily dissolve lipids?
What isn't? -
-organic solvents
-water - Why do lipids give so much energy?
- -when hydrolyzed, they are highly reduced
- What makes lipids useful in membranes? (special term).
- -they're amphipathic
- What are 7 diverse groups of lipids?
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-fatty acids
-triglycerides
-phospholipids
-sphingolipids
-glycolipids
-waxes
-terpenoids - What are 4 functions of lipids?
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1) fat droplets in adipose tissue for storage of carbon and energy
2) physical and thermal insulation
3) form lipoproteins to transport lipids to the tissues
4) steroid and eixosanoid hormones - Describe 3 characteristics of fatty acids?
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-complex lipids contain fatty acids
-carboxylic acid with a long straight carbon chain 4-30 carbons (most have 14-24)
-can be saturated, no double bonds, monounsaturated or polyunsaturated - What are some common saturated fatty acids?
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-palmitic acid (CH3(CH2)14CO2-) (16:0)
-stearate octadecanoic acid (18:0) CH3(CH2)16CO2- - What are some unsaturated monounsaturates?
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Oleic Acid (18:1)
(CH3(CH2)7(CH=CHCH2)7CO2-) - What are some polyunsaturates?
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When does stearic acid melt?
How about Oleic acid? -
-70 C
-14 C - What are some fatty acids that are found as esters in complex lipids?
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-triacylglycerols
-phospholipids
-plasmalogens
-sphingolipids
-glycolipids - What makes up micelles?
- -phospholipids
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In digestion, what emulsifies fats?
-What happens after this? -
-bile acids in intestine
-emulsifies fats are hydrolysed by lipases - How are fats transported in the blood?
- -as lipoprotein complexes (Chylomicrons)
- What forms a Ceramide?
- -if a fatty acid is linked to the 2 amino group of sphingosine
- How do you form a Sphingomyelin?
- -add a phosphocholine to the 1 hydroxyl of a Ceramide
- What are waxes?
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-protective coating on fruits and leaves
-secreted by insects
-long chain hydrocarbons, alcohols, and ketones which may be linked to fatty acids - What are terpenoids?
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-biosynthetically built from isoprene
-huge class of plant products
-steroids are terpenoids - What are 5 functions of a membrane according to BioChem?
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-exclusion of toxic molecules
-accumulation of cell nutrients
-energy transduction
-signal transduction
-interaction with other cells - What is the difference between liquid crystal membranes and gel membranes?
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-liquid crystal have loosely packed heads and disordered tails; thinner membrane
-gel had tightly packed heads and regular tails; thicker membrane - How was phospholipid flipping monitored?
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-cells labeled with radioactive phosphorus (P-32)
-cells treated with TNBS to bind amine groups to membrane Phosphatidyl ethanolamine
-at first no molecules with both labels appeared in newly synthesized PE on inner layer
-after 30 min, some PE with both labels found in PE so phospholipids are slowly "flipped" across the membrane - What are 4 membrane proteins?
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-transport proteins
-signal receptors
-electron transport
-photosynthesis - What are two types of transport across a membrane?
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-active
-passive - What are the divisions of passive transport?
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-simple diffusion
-facilitated diffusion (pores and channels, carrier molecules) - What are divisions of active transport?
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-primary
-secondary - What does Gramicidin A do?
- -makes a cation-specific pore through the membrane
- What is the number one example of active transport systems?
- -the sodium/potassium pump