Lipids Flashcards
Types of lipids
Fats/Oils
Phospholipids
steriods
waxes
Roles of lipids
- Storing energy
- building cell membrances
- communication as chem signals
- Insulation
Lipids atom + structure
- Composed of C, H, and O (though fewer O then carbohydrates) No nitrogen in lipids, they are hydrocarbons. lipids are long carbon chains, hydrophobic (non-polar mostly)
- Hydrophobic due to high proportion of C-H bonds
- Efficient energy storage due to C-H bonds (twice as much as carbohydrates, not as easily accessible by cells) hard to access the energy because it is harder to break the bonds
- Long term storage, processed after carbohydrates we burn carbs first
- Insulate against heat loss, protect organs, component of cell membranes
energy storage for lipids
animals convert excess carbs into fat
carbs: 4kcal/g
protiens: 4kcal/g
Lipids: 9kcal/g
Energy Storage:
Triglycerides (fats and oils)
Most common fat in plants and animals
Triglyceride = 1 glycerol + 3 fatty acids linked by Ester Linkages
Glycerol = three-carbon alcohol (three –OH groups) Fatty acids are long hydrocarbon chains containing a single carboxyl group (–COOH) at one end
Formation of Triglycerides (linkages and reations used)
Polymer
1, 2, or 3 fatty acids can join to the glycerol to make monoglycerides, diglycerides or triglycerides
Triglycerides are the most common.
Linkages
Ester linkage
Between –OH on glycerol and –COOH on fatty acid
Reactions
Build: Condensation reaction (dehydration)
Break: Hydrolysis
Saturated Fatty Acids
Saturated fatty acids have only single bonds between carbon atoms and have the maximum number of hydrogen atoms attached to the carbon skeleton
Saturated fatty acids come from animal fats:
beef, pork, cheese, butter
coconut oil ← only plant to do this
easier to stack
-less space between molecules
-solid at room temperature
-animals store fat as saturated fats
-cholesterol + saturated fat makes plaque in our body
Unsaturated fats
Unsaturated fatty acids have at least one double bond between carbon atoms and have fewer than the maximum number of hydrogen atoms attached to the carbon skeleton
Unsaturated fatty acids come from plant fats:
Olive oil, canola oil, safflower oil
cant stack well/liquid
arent good bc of isomers (double bonds are an area of rigidity)
trans fats
if the isomer is trans, (trans fats) → do not exist naturally
- we have not developed the means to break them down
- float around in our blood stream and interract with bad stuff, causing heart disease
trans fats are formed by hydrogenation
can turn a double bond temp into a single bond, so rotation can happen.
- h’s rotate and double bond is created again
- creates trans isomer
- can happen during cooking
Cis and Trans Unsaturated Fats
- In unsaturated fatty acids, there are two ways the pieces of the hydrocarbon tail can be arranged around a C=C double bond
- In cis bonds, the two pieces of the carbon chain on either side of the double bond are either both “up” or both “down,” such that both are on the same side of the molecule
- In trans bonds, the two pieces of the molecule are on opposite sides of the double bond, that is, one “up” and one “down” across from each other
Phospholipids
Composed of 2 fatty acids + 1 phosphatidylcholine
phosphatidylcholine = glycerol + phosphate + choline
fatty acids are non-polar (hydrophobic tails)
phosphatidylcholine is polar (hydrophilic head)
Amphipathic 🡪 have both hydrophobic and hydrophilic portions
Used to make cell membranes
Lipid bilayer
Forms a lipid bilayer
Hydrophilic head faces aqueous environment and interior of cell.
Hydrophobic interior of membrane prevents movement of water through membrane
Cell membrane must have proteins and hydrophilic pores that form channels through which charged materials can pass
The cell membrane is selectively permeable
The bilayer does not allow materials to pass through it
There are channels (proteins and pores) that control what materials enter and exit the cell
Steroids
4 attached hydrocarbon rings and several functional groups
e.g. cholesterol (causes arteriosclerosis in high concentration, precursor of vitamin D), testosterone, estrogen, progesterone – sex hormones.
Made in body, also consumed
Reduce inflammation
Myelin Sheath
Myelin is a sheath (a covering) over the nerve cells
Aids in transmission of impulses through the nerves
Composed of phospholipids and cholesterol (and proteins)
Multiple Sclerosis
Waxes
Lipids containing long-chain fatty acids linked to alcohol or carbon rings
Solid at room temperature
Waxes form waterproof coatings
Cutin
Bird feathers
Beeswax
Waxes are highly hydrophobic lipids
Are quite firm and pliable – ideal to form waterproof coatings on various plant and animal parts
Form cutin from plant epidermal cells (water-resistant coating on leaves, stems, and fruits) to prevent water loss
Waxes on bird feathers prevent them from getting wet
Beeswax is produced to make honeycombs
