Chapter 9 Review Flashcards
Three roles of lipids
- Form bilayers that make up biological membranes
- Have hydrocarbons that serve as energy stores
- Many intra- and intercellular signaling
Lipids are soluble in _______ solvents.
Organic
Lipids make:
- Fats
- Oils
- Some vitamins
- Some hormones
- Nonprotein membrane components
Define fatty acids
Carboxylic acids with long- chain hydrocarbon side groups. Most are found in the esterified form.
Lipids ______ polymerize. Stick together due to ________, this __________ it.
can’t ; entropy, which increases it.
Fluid Mosaic Model
- Membrane is not rigid and does not have a fixed orientation.
- Contains glycoproteins
- Contains integral proteins
Glycoproteins
Membrane protein with oligosaccharides (carbohydrates) attached. On the extracellular side.
Integral Proteins
Amino acids on the surface of the membrane with lipids–> hydrophobic –> polar residues. Go all the way through the membrane.
Glycolipid
Lipid with carbohydrate attached. Extends into the extracellular area.
Fatty acids will connect to the ______ of the triglycerols.
R-group
Saturated Fats
- NO double bonds present, completely reduced (packed with H atoms).
- This causes them to pack closer together. Less reactive, higher melting point
- Highly flexible and can assume a large range of conformations
Unsaturated Fats
Has at least one double bond present. Cis-formation –> causes kink in the chain and multiple unsaturated fats can’t pack close together like saturated fats can. Lower melting point due t the reduced van der Waals forces
Glycerophospholipid head is made of
A phosphatic acid head and two fatty acid tails
Why are glycerophospholipids bent?
- Not saturated
- Double bond adds kink, which adds rigidity
How does phospholipase breakdown a lipid?
It binds close to the membrane and “chops” off the tail through hydrolyzation. It catalyzes the hydrolytic reactions.
The fluidity of lipids ______ with the increase in degree of unsaturation.
Increases
Triacylglycerols (aka triglycerides)
- A lipid in which three fatty acids are esterified to a glycerol backbone.
- Nonpolar
- Water insoluble
- Fatty acid triesters of glycerol
- Function as energy reservoirs
- Most ABUNDANT class of lipids
- Provide more energy than glycogen
Triacylglycerols
Long-term energy storage
Glycogen
Short-term energy storage
Glycerophospholipids are a major lipid component of ________.
Biological membranes
Plasmalogens
- a type of phosphoglyceride.
- The first carbon of the glycerol has a hydrocarbon chain attached via an ether.
- Central carbon (C2) has a fatty acid linked by an ester.
- The third carbon links to an enthanolamine or choline by means of a phosphate ester.
- Important component of muscles and nerves.
Vitamins stay in the membrane except vitamin _____.
D
The only water soluble vitamin
Vitamin C
Vitamin essential for blood clotting
Vitamin K
Vitamin important for picking up wavelengths in the eye.
Vitamin A
Why is only having one tail not go for phospholipid heads?
- They form spheres:
- Allows water gaps
- Not good, entropy decreases
- Allows the cells’ insides (the HYDROPHOBIC REGION) the potential of coming into contact with water
If hydropathy is positive
hydrophobic
If hydropathy is negative
hydrophilic
Phospholipases do what?
Hydrolyze Glycerophospholipids
Integral Proteins are ________ membrane associated.
Tightly
Gangliosides
- Mostly makeup cell-surface membranes
- Make up 6% of brain cell lipids
- Act as specific receptors of certain pituitary glycoprotein hormones ( their complex carbohydrate heads act as the receptors).
- Receptors of certain bacterial protein toxins
- Could be specific determinants of cell-cell recognition
Gangliosides
Gangliosides are important for:
- Cell growth
- Cell differentiation
- Carcinogenesis
Steroids are _______-fused nonpolar rings.
four
The most abundant steroid in animals and a big portion of it makes animal plasma membranes.
Cholesterol
Polar OH group means
weak ampihilic nature
The four-fused ring system of steroids
- adds a greater rigidity
- can be esterified to long-chain fatty acids
Vitamin D is a ________.
Steroid
Fat-soluble vitamins include
- Vitamin A
- Vitamin K
- Vitamin E
Transverse Diffusion
The transfer of a lipid across a bilayer. Extremely rare. Requires hydrated, polar head group to pass through the hydrocarbon core of the bilayer
Lateral Diffusion
The pairwise exchange of neighboring phospholipid molecules in the same bilayer half.
Chaotropic Agents
- Disrupt the water structure
- Reduces the hydrophobic effect (which is responsible for stabilizing the association of the protein with the membrane)
Beta-barrel structures are
antiparallel beta sheets that roll up
Porins
- Channel-forming proteins in the outer membrane of gram-negative bacteria.
- Beta-barrels make these.
- Permit the entry of smaller polar solutes
