BIOL 301 Study Guide - Final Guide: Retinoid, Phosphoglucomutase, Catechol
Final Exam Study Guide
LIPIDS
- Energy Storage, Cell Structure, Signaling
- Structure of a fatty acid based on first part of name / structure:
o Ex. 18:1 (∆9) cis-9-Octadecenoic acid
▪
▪ 18 = number of carbons in the structure
▪ 1 = number of double bonds in the hydrocarbon
▪ ∆ = position where there is double bond- starting at carbon 9
• it is a CIS double bond as indicated – which are most common
form
o Ex.
▪
▪ This would be 18:1 (∆9) Trans-9-Octadecenoic acid
o Omega-3 or -6 fatty acid
▪ Numbering in the opposite direction
▪ FINAL carbon is omega carbon = position 1
▪ Double bond at position 3 → Omega-3 fatty acid
▪ Double bond at position 6 → Omega-6 fatty acid
- Length & Saturation
o Longer chains → lower solubility because they associate with each other, so
solid structure that will precipitate out of solution
o Longer → less fluid because more association
o More saturation (less double bonds, less kinks) → less fluid
▪ This is because the kinks make it harder for the lipids to pack close
together so there is more space between the molecules, making it
more fluid. More kinks → more fluid
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- Fats – as energy storage
o 3 Fatty acids + a glycerol = triacylglycerols (aka, triglycerides, fats)
o Very insoluble – making it light because no extra water weight→ advantage
as a fuel
o Stored in cells in adipocytes
▪ Serve as energy storage
o Holds a lot of energy because in a saturated fatty acid- a lot of hydrogens,
more electron density, more energy associated with it (than sugars, for ex)
o Wax – used to keep water inside (of body, leaves, etc..)
▪ Two hydrocarbon chains linked together with an ester
- Phospholipids – lipid bilayer
o 2 fatty acid chains
o amphipathic – hydrophilic heads facing out, hydrophobic tails facing in
o makes it hard for hydrophilic molecules to come through into/out of cell
▪ → controls what goes in or out
o in water, self-organize into bilayers and form liposomes
▪ hollow balls filled with water and barrier separating inside and
outside
o Abbreviations for phospholipids
▪ Different types of content depending on which organelle/ which face
of the bilayer
▪ PE (phosphatidylethanolamine), PC (phosphatidylcholine), PS
(phosphatidylserine), PI (phosphatidylinositol)
o Membrane also has diff types of proteins, cholesterol, carb groups, etc.
- Specific Types of Membrane Lipids
o 1. Glycerophospholipids (phospholipids)
▪ Glycerol backbone with 2 fatty acids and a polar/charged group
attached by phosphodiester linkage
▪ Usually C-16 to C-18 saturated and C-18 to C-20 unsaturated
▪ Naed aordig to polar alohol of the head group
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• If the alcohol is just H → phosphatidic acid
▪ Head structures for phosphatidylinositol and phosphatidylserine
• Phosphatidylinositol – head structure: myo-Inositol 4,5-
biphosphate
• Phosphatidylserine—head structure: serine
o 2. Sphingolipids (can be phospholipids OR glycolipids)
▪ Sphingosine backbone with fatty acid and X group which determines
the sphingolipid
• If X group is H→ ceramide
▪ Sphingomyelins
• No net charge on the head group
• Are phospholipids
• Phosphocholine or phosphoethanolamine as head group
▪ Glycosphingolipids
• Head groups are SUGARS
• No phosphate
▪ Gangliosides
• Membrane lipids where polar head group is complex
oligosaccharide with sialic acid residues
• Can have single or multiple Sialic acid residues
o 3. Sterols
▪ 4 fused ring structures with hydrocarbon tail
▪ mostly hydrocarbon (hydrophobic) but OH group at end of rings
(hydrophilic)
• SO overall→ amphipathic
▪ EX. Borrelia bug- a’t ake cholesterol so they get it from their host
that they infected
▪ EX. Form of steroid: Taurocholic acid (a bile acid)
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