Chapter 5: Lipid Structure and Function Flashcards Preview

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Flashcards in Chapter 5: Lipid Structure and Function Deck (30):

Amphipathic molecules

molecules that have both hydrophillic (polar) and hydrophobic (nonpolar) parts 


Hydrophilic (polar) portion is on the outside, in contact with water.

Hydrophobic (nonpolar) portion is on the inside




Membrane lipids: Which area of the membrane is hydrophillic and hydrophobic?

  • The outer parts of the membrane are the polar hydrophillic heads.
  • The inner parts of the membrane are the nonpolar hydrophobic fatty acid tails


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Define Phospholipids

Why are they important?

Structure? Draw the 3 major components

What bonds connect them?

Are all sphingolipids also phospholipids?

Why or why not? Which sphingolipid is? Why?

  • Molecules with 3 components:
    1. Hydrophilic polar head group 
      • Phosphate and alcohol
    2. Backbone
      • Glycerol, Sphingosine, or Sphingoid
    3. Nonpolar hydrophobic long-chain fatty acid tails
  • They are important because they make up part of the cell membrane
  • The hydrophilic polar head group is connected to the backbone by a phosphodiester bond
  • Not all sphingolipids are phospholipids
    • They must have a polar head group with phosphate and alcohol to be phospholipids
  • The only sphingolipid that is a phospholipid is spingomyelin, because it has a polar head group of phosphate and alcohol



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Fully Saturated vs Unsaturated Fatty Acids

What kind of bonds? And what state are they often in?

  • Fully Saturated fatty acids only have single bonds and are more solid.
  • Unsaturated fatty acids have one or more double bonds and are more fluid 
    • they are more fluid because the double bonds cause kinks in the fatty acid chain, making it harder for them to stack and solidify



Define Glycerophospholipids

What kind of lipids are they?


What kind of bonds connect its parts?


  • Phospholipids with:
    • Polar head of phosphate and alcohol 
    • Glycerol (3 carbon) backbone
    • 2 Nonpolar long-chain fatty acid tails
  • Polar head-Glycerol backbone are connected by a phosphodiester bond
  • Glycerol-Nonpolar fatty acid tails are connected by 2 ester bonds


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Define Sphingolipids

Why are they important?






4 major types of sphingolipids?


  • Lipid molecules:
    • Polar head group
    • Sphingosine or Sphingoid backbone
    • 1 nonpolar fatty acid tail
  • They are important because they make up part of the cell membrane
  • Some are phospholipids, connected by phosphodiester bonds
    • Sphingomyelin
  • Others are not phospholipids, cause they don't have phosphodiester bonds
  • Some sphingolipids have glycosidic bonds to sugars, thus, they are called glycolipids
  • Types of sphingolipids:
    1. Ceramides - single hydrogen atom as the head group
    2. Sphingomyelins - has a phosphodiester bond; thus, a phospholipid
    3. Glycosphingolipids - sugar head group connected by glycosidic bond
    4. Gangliosides - have oligosaccharide polar head group with sialic acid (NANA)

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The four types of sphingolipids:

What are the bonds of each?

What are the head groups?

Which ones are phospholipids?

  1. Ceramide - sphingolipid with a hydrogen atom as its polar head group
  2. Sphingomyelin - sphingolipid with either a phosphatidylcholine or phosphatidylethanolamine head group
    • Important for the myelin sheath
    • Connected by phosphodiester bonds (phospholipid)

  3. Glycosphingolipid - sphingolipid with sugar(s) head group

    • Connected by glycosidic bonds

    • Cerebroside - 1 sugar head

    • Globoside - multiple sugar heads 

  4. Ganglioside - sphingolipid with multiple sugars and NANA (sialic acid)  as its head group

    • Connected by glycosidic bonds

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  1. Define Terpenes
  2. What are they used for?
  3. Isoprene vs Terpene
    • What are the molecular formulas of each?

  1. Terpenes are a class of lipids made up of multiple isoprene subunits
  2. Terpenes are the precursors to steroids and other lipid signalling molecules
  3. Isoprene vs Terpene
    • Isoprene: C5H8
    • Terpene: C10H16
      • Terpene = Two Isoprenes




What are they derivatives of what compounds?

Steroids are compounds with three cyclohexane rings and one cyclopentane ring. 


Steroids are derivatives of terpenes 

Terpene = C10H16​​


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Steroid hormones

  1. soluble or insoluble in water? how do they travel?
  2. Do they bind outside or inside the cell?
  3. What happens when they bind to receptors?
    • Do steroid hormones bind directly to DNA?
  4. Suffix?


  1. They are insoluble in water and are carried through the bloodstream via protein carriers
  2. They enter cells and bind to receptors within them
  3. The receptors then affect gene expression and metabolism 
    • The steroid hormone alone does not affect them directly
  4. Suffix: -one -oid -ol


What is Cholesterol and what does it do?

What is it a precursor of?

  • CholesCholesterolsteroid 
  • It an amphipathic steroid which interacts with the cell membrane to maintain its fluidity
    • Amphipathic: has hydrophilic and hydrophobic parts
  • Interacts with hydrophilic polar heads and hydrophobic nonpolar fatty acid tails
  • It is a steroid because it contains three cyclohexane rings and one cyclopentane ring
  • It is also a precursor to steroid hormones, bile acids, and vitamin D


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What make its?

What are their functions?

  • Prostaglandins are lipid compounds that act like hormones via autocrine or paracrine signaling.
    • Autocrine - cell signals itself
    • Paracrine - cell signals nearby cells
  • Prostaglandins are produced by almost all cells in the body.
  • They have many hormone-like effects on the body.
    • Affects smooth muscle function, pain, body temperature, inflammation, blood pressure, circadian rhythms, etc.
    • Also, regulates hormones



Vitamin A

What is its other name?

What is its function?


  • Vitamin A is a signaling lipid and an essential nutrient
  • Also called Carotene
    • Remember: Carots are good for vision
  • Important for vision and epithelial tissue development
  • Fat soluble vitamin.



Vitamin D

What is it another name for it?

Important for?

Derived from what?

  • Vitamin D is a signaling lipid and an essential nutrient
  • Also called Cholecalciferol 
    • Remember: Vitamin D is important for Chole"calci"ferol (calcium)
  • Important for calcium and phosphate regulation to build strong bones
  • Fat soluble vitamin
  • Derived from cholesterol (a steroid)


Vitamin E

  • Vitamin E is a signaling lipid and an essential nutrient
  • Also called Tocopherol
  • Important antioxidant which prevents oxidative damage using its aromatic ring 
  • Fat soluble vitamin


Vitamin K

Also called?

Important for what?

  • Vitamin K is a signaling lipid and an essential nutrient
  • Also called Phylloquinone or Menaquinone 
  • Important for producing prothrombin and clotting blood
    • Remember: Vitamin K is important for Koagulation (blood clotting)
  • It is also necessary for calcium-binding sites
  • Fat soluble vitamin


Are lipids or carbohydrates (glycogen) better for energy storage?


  • Lipids are best for energy storage; better than any other macromolecule in the body
  • 2 reasons
    1. Lipids have more reduced carbon atoms with hydrogen, which yield more energy when oxidized​
    2. Lipids are nonpolar hydrophobic, so they are lighter weight cause they don't need hydration









Nonpolar hydrophobic energy storing lipids composed of a glycerol backbone connected to three fatty acid tails via ester bonds.

  • Also called Triglycerides
  • Nonpolar because they don't have a polar head
  • Triacylglycerol is fat
  • Functions:
    • Energy storage
    • Insulation
    • Padding

Triacylglycerols give much more energy per gram than carbs give

  • Because triacylglycerols are much more reduced
  • They can be oxidized much more than carbs can


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  • Fat storing cells in animals that contain large deposits of triacylglycerols (fat) in their cytoplasm
  • Triacylglycerols are lipids that store energy
  • Remember: Adipose tissue is fat tissue



reactants? products?


  • Reactants: Water, NaOH,  Triacylglycerol
  • Products: Glycerol and soap.
  • The process when a triacylglycerol is broken down into its parts via Ester Hydrolysis.
  • Water is added to the ester bonds, cleaving them
  • Triacylglycerol is cleaved into its glycerol backbone and its three fatty acid tails
  • The sodium (Na) from NaOH binds to the free fatty acids to form soap.

Free fatty acids binds to sodium, becoming soap!

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do all sphingosines have a spingosine backbone?

  • No, spingosines are lipids that can have a spingosine or spingoid
  • The backbone is connected to the head group and fatty acid tails via either phosphodiester or glycosidic bonds.


Lipids and solubility


what are the insoluble in?

what are they soluble in?


insoluble in water (cannot be dissolved in water)

soluble in nonpolar, organic solvents


Three major functions of lipids

Lipids are involved in:

  1. Structure
    • Lipids make up vesicles, liposomes, and membranes
  2. Signaling
    • Lipids are enzyme cofactors, light-absorbing pigments, intracellular messengers, and hormones
  3. Energy storage
    • Give the most energy by weight of any other molecule




what are they at room temperature? (solid/liquid/gas?)


what role do they play?

Waxes are lipids

Esters of long-chain fatty acids with long-chain alcohols

Waxes are solid at room temperature

They are lipids with structural roles, such as the structure of honeycombs in bee's nests


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fat soluble vitamins?


what does the body do with them?


vitamin A

vitamin D

vitamin E

vitamin K


They can accumulate in stored fat


Fatty acid structure?

carboxyl group connected to a long chain of carbons


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Lipid solubility

lipids are hydrophobic and nonpolar


they are soluble in the same type

soluble in nonpolar organic solvents



Can we produce them?

organic molecules that are essential to our bodies

we cannot produce them, so we get them from diet


Heat of combustion of macromolecules question

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Lipids (Fats) are the most reduced because they have the most carbon and hydrogens bonded; thus, they can be oxidized the most for more energy.


Saturated fats are even more reduced than unsaturated fats, because they only have single bonds; thus, more hydrogens attached

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A lipoprotein with low density means what about its protein and lipid ratio?


what about high density lipoproteins?

proteins are more dense than lipids are

Proteins have greater mass, thus they are more dense


Low-density lipoproteins have more lipids than proteins (proteins < lipids)


High-density lipoproteins have more proteins than lipids (proteins > lipids)