Chapter 8 Flashcards
What are lipids and how are they grouped together?
Lipids at hydrophobic biological compounds that are grouped together because they are insoluble in water
What are the 5 biological functions of lipids?
Energy storage (fat in animals, oils in plants)
Structural role (building blocks of membranes
Biochemical signals (signal messengers)
Enzyme cofactors
Pigments
What is the simplest backbones of lipids?
CH3-(CH=CH)n-CHO
n=6-9
What’s the difference in storage between carbohydrates and fats?
There’s enough fat in storage to cover energy requirements for weeks while carbohydrates (glycogen) only has enough for one day in humans
Fat is more efficient but carbohydrates burn faster
What is an ester bond?
The result when an alcohol reacts with a carboxylic acid
R1-OH + HO-C-R2 -> R1-O-C-R2
|| ||
O O
Picture on slide 6
What are triacylglycerols?
Storage lipids in animals and plants
Starts with glycerol, then has 3 fatty acid tails extend from each OH of glycerol
Each tail has an even number of atoms that are between 12 and 24 carbon atoms long
What is the difference between saturated fatty acids and unsaturated fatty acids?
Saturated- no double bonds for carbons
Can pack in compact arrays (max van der waals interactions)
Unsaturated- have 1-3 double bonds (usually between C9-10, C12-13, and C15-16)
Double bonds introduce kink in the chain resulting in less regular packing and higher thermal motion
What is the carbon skeleton notation of fatty acids?
X:Y(Δ^c)
X is equal to the number of carbon atoms
Y is equal to number of double bonds
C is the carbon atom where the double bond starts
Examples on slide 7
How is the melting point affected by the length of the hydrocarbon chain?
The number of double bonds?
The longer the hydrocarbon chain (more carbons), the higher the melting point
The more double bonds, the lower the melting point
What are triacylglycerols containing saturated fatty acids?
Unsaturated fatty acids?
Saturated- solid at room temperature (animal fats)
Unsaturated- liquid at room temperature (plant oils)
Double bonds in natural plant oils are cis configuration
Double bonds in hydrogenated vegetable oils are trans configuration
What is cis and trans configuration?
Cis- ==/
Trans- /==/
Why are trans fatty acids not good?
They increase the level of “bad cholesterol (LDL) and decrease the “good” cholesterol (HDL)
What is the biological oxidation or combustion reaction?
What do lipids react with?
CmHnOp -> CO2 + H2O
Exergonic
Lipids react with oxygen
More oxygen incorporated into reaction, less energy released
How is fat stored in plants?
In compact dat droplets so there is no need for hydration water
What are the structural lipids that form cel membranes?
Since the membrane must be water repellent, the structural lipids need a polar (hydrophilic) headgroup and an apolar (hydrophobic) tail
What are the structural lipids glycerophospholipids, sphingolipids, and galactolipids?
Glycerophospholipids- have glycerol backbone and two fatty acid chains coming off then the third is a phosphate group (PO4) and an alcohol attached
Sphingolipids- has sphingosine as backbone that takes up one fatty acid spot then has one fatty acid coming off it and a phosphate group or mono/disaccharide with choline attached
Galactolipids- have glycerol backbone with two fatty acid chains and a mono or disaccharide with a sulfate group attached (SO4)
Look at picture on slide 11
What are glycerophospholipids derivatives of?
Do flash cards of the common glycerophospholipids
Phosphatidic acid
Flash cards are in backpack
What do the chloroplast membranes in plants contain?
Why do they contain these over phosphate?
Galactolipids and sulfolipids
Plants may have galactose and sulfate instead of phosphate because phosphate is often a limiting nutrient that is needed for critical functions
What are either bonds?
Why are they used sometimes in lipids instead of ester bonds?
R1-OH + HO-R2 -> R1-O-R2
When the the alcohols of two groups take out a water and connect straight by one oxygen
Ether bonds are much more resistant to hydrolysis (this adds stability) and they are more resistant to enzymatic digestion by lipases
What are glycerol dialkylgylcerol tetraether lipids?
They are found in archaebacteria and are one membrane that extends all the way around the cell since it has two chains connected to two ends by ether bonds
Picture on slide 15
For the side groups of sphingolipids, what’s the difference between ceramide, sphingomyelin, glucosylcerebroside, lactosylceramide, and ganglioside GM2?
Ceramide is just H
Sphingomyelin is the only straight chain
Glucosylcerebroside is neutral and is just one glucose circle
Lactosylceramide is neutral and is a di tri or tetrasaccharide (diagram has two hexagons)
Ganglioside GM2 has complex oligosaccharide
Table on slide 16
Where is sphingomyelin found?
What about cerebrosides?
Sphingomyelin is in the axon sheath of neural cells
Cerebrosides are found in the plasma membrane
How do glycosphingolipids play a role in ABO blood type?
The antigen determinants of the ABO group are oligosaccharides that form headgroups of the sphingolipids on the surface of red blood cells and are attached to proteins
Blood type is determined by oligosaccharides that are apart of a glycosphingolipid molecule
What are phospholipids and sphingolipids degraded by?
Enzymes in lysosomes
Phospholipids and sphingolipids are constantly recycled in the cell
Enzymes called lipases cleave the bonds connecting fatty acid chains and polar headgroups
What are sterols?
How can you tell if something is a steroid molecule?
They can be structural lipids like cholesterol in animal tissue or precursors of steroid hormones and bile acids
You can spot a steroid molecule if it has 4 fused carbon rings called the steroid nucleus
If it has a charged headgroup and the four rings it is a bile acid
How is 7-dehydrocholesterol concerted into cholecalciferol (vitamin D3) with UV light and then how is this converted to 1,25-dihydroxycholecalciferol?
The 2nd of 4 rings of 7D is broken up at carbon 9 and 10 and so it extends while the other three carbon rings stay intact, the 1,25 is formed in the liver and kidney by the addition of two OH molecules on either end of the molecule
This is how vitamin d is made in the body from sunlight
Picture on slide 21
What does vitamin d deficiency cause?
Abnormal bone development (rickets disease)
Can be fixed by introducing more vitamin d into system
How is vitamin A1 converted into visual pigment retinal?
β-carotene->VitaminA1 (retinol)
carotene is cut in half and top half is taken
VitaminA1->11-cis-retinal- carbon 11 turns to cis from trans and the bottom alcohol turns to aldehyde (CH2OH to COH)
11-cis-retinal->all-trans-retinal- carbon 11 is changed back to trans when a photon hits the retina
Picture on slide 23
What is retinal?
A cofactor of rhodopsin, a light receptor protein in the human eye
The red colour of the retina is due to retinal
What is isoprene?
Common building block of many lipid cofactors (natural rubber)
CH3
| CH2=C-CH=CH2
Dotted sections of β-carotene are all isoprene
Picture on slide 25
What is the difference between vitamin K and E?
E- has two fused carbon rings with O in the second carbon ring and 3 CH3’s hanging off the first one
Prevents oxidative damage to lipids
K- two fused carbon rings with two double bonded oxygens hanging off the second ring
Undergoes cycles of oxidation and reduction in prothrombin activation (blood clotting)
Picture on slide 26
What is the difference between quinol and quinone?
Quinol has hydroxide groups around its carbon ring
Reduced form of ubiquinone
Quinone has ketone groups around its carbon ring (=O)
Oxidized form of ubiquinone
What is the function of ubiquinone?
Shuttles electrons in the mitochondrial membrane from a protein donor to a protein acceptor
Drawing beside slide 27
