lipids 2
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- definition of a lipid
- small, water insoluble molecule that is soluble in organic non-polar solvents
- 2 major roles of lipids
-
-major structural component of membranes
-major store of energy - what are the two classes of lipids
-
-simple lipids (don't contain fatty acids, like cholesterol).
-complex lipids (do contain fatty acids, like TAG's and Phosphatides - What type of bond links fatty acids to complex lipids?
- ester or amide links
- what types of cells are TAG's in?
- ADIPOSE - fat cells
- what is the role of Phosphatides?
- MEMBRANE lipid components
-
what is the backbone of
-TAGs
-Phosphatides - GLYCEROL!
- what does a TAG consist of?
-
-Glycerol backbone
-3 Fatty acid tails - What does a Phosphatide consist of?
-
-Glycerol backbone
-2fatty acid tails
-Phosphate! - what does the term amphipathic refer mean, and what does it refer to?
- the fact that phospholipids are both polar and nonpolar in different areas.
- what are the two major components of a BIOMEMBRANE?
- proteins and lipids
- what percentage of lipid structure is composed of carbohydrates, and in what two forms?
-
2 to 10%
-Glycolipids
-Glycoproteins - What are glycolipids
- Sugar-containing lipids.
- What 3 kinds of membranes have varied proportions of lipids/proteins?
-
-protein-rich: mitochondrial (proton pumps)
-lipid-rich: myelin sheath - neurons - very insulating.
-equal parts: like plasma membrane - what is the percentage composition of a myelin membrane?
-
LIPID RICH
75% lipid
25% protein - what is the percentage comp. of inner mitochondrial membrane?
-
-PROTEIN RICH
-75% protein
-25% lipid - what type of membrane has equal parts lipid/protein
- plasma membrane (cell membranes!!!)
- what types of lipids are often zwitterions?
- -PHOSPHITIDATES - cuz they have the alcohol component, which can be from like a serine or amino acid.
-
what types of aggregates do
-fatty acids form
-phosphatidates form -
-micelles
-lipid bilayers - 2 Ways proteins associate with lipid bilayer:
-
-Integral proteins
-peripheral proteins - What does the Fluid Mosaic Model propose:
- proteins diffuse within plane of the lipid bilayer but do not flip in it.
- what is the role of peripheral proteins?
-
attach to lipid bilayer surface:
-noncovalent bond to integral proteins
or
-lipid tether - what is the role of integral proteins
- most extend all the way through the membrane. make contact with hydrophobic interior of membrane.