Ch. 3 Lipids (Exam 1) Flashcards
Classes & Functions of Lipids, Fatty Acids, Triglycerides, Phospholipids, Isoprenoids/Steroids, Lipids & Membrane Structure
What are the 3 major functions of a lipid?
1) Energy storage
2) Membrane function
3) Signaling molecules
What are the 5 major classes of lipids discussed in class?
1) Fatty acids
2) Triglycerides
3) Phospholipids
4) Sphingolipids
5) Isoprenoids/steroids
What are the 2 distinct regions of a fatty acid?
1) Large hydrocarbon tail
2) Short carboxylic head
Which carbon is C1 in delta notation?
The carboxyl
What is the lipid number format?
C#1:#2 where #1 represents # of carbons present and #2 represents # of double bonds present
Which carbon is C1 in omega notation?
Carbon at end of chain/tail
What is the max number of carbon for a monocarboxylic acid?
24
Where do most animals get their fatty acids from?
Food/diet
Will you mostly find FAs in cis or trans-conformation?
Cis
How many double bonds do you notate in omega notation?
Only the first one
Which state of matter are saturated fats in a room temperature?
Solid
Which state of matter are unsaturated fats in at room temperature?
Liquid
What is the general structure of a triglyceride?
Glycerol ester bonded w/ 3 fatty acids
How does length of a triglyceride allow for greater energy storage?
Longer, hydrophobic FA = less water in fat cells = greater storage efficiency
What do animals use fatty acids for?
Energy storage
What do plants use for energy instead of lipids?
Carbs
Where are lipids found in plants?
Seeds
How do fats and oils differ in saturation and state of matter at room temp?
Fats are usually saturated, so solid at room temp while oils are unsaturated, so liquid at room temp
What are phospholipids polar?
B/c of the phosphate group
What is the general structure of a phospholipid?
Same as triglycerides but w/ phosphate group at 3rd position (glycerol backbone, FA, FA, phosphate group)
Which phosphate pKa is closest to physiological pH?
pK2 at 6.6
How many times can a phosphate be esterified?
3
Are are two reasons that phospholipids have heterogeneity?
1) FAs in 1st 2 positions can vary
2) Different alcohols can esterify to phosphate
What is an example of an amino-alcohol?
Phoshatidylcholine
What are 3 important uses of phospholipids?
1) Membrane formation
2) Emulsification
3) Surfactants
What 2 interesting structures can phospholipids become?
1) Micelles (pizza)
2) Phospholipid bilayers (french fry)
How are steroids structured?
4 flat-ringed systems
What are steroids an important component of what part of an animal cell?
Animal cell membranes
What are 2 common uses biochemical functions of steroids?
1) Hormones
2) Cholesterol
In which organisms can steroids be found?
All eukaryotes and some bacteria
What are 2 ways to differentiate steroids?
1) Double bond placement
2) Substituents
What is another term for steroid?
Isoprenoid
What are 3 common types of steroids?
1) Cholesterol
2) Estradiol
3) Testosterone
What are the two conflicting natures of lipids?
1) Water solubility
2) Lipid solubility
Which 3 structures can be formed to remedy the conflict between water and lipid solubility?
1) Micelles
2) Liposomes
3) Phospholipid bilayers
What are the 3 liposome phases?
1) Exterior water
2) Interior water
3) Nonpolar
Under what condition does a bimolecular membrane lipid form?
Low concentrations
What does membrane fluidity refer to?
Viscosity of the bilayer
What movement is responsible for the normal function of membrane lipids?
Rapid lateral movement
What is the consequence of liposomes have two water phases?
2 completely different solutions can be on either side of the membrane
What do the channels and transfer proteins transport through lipid membranes?
Sodium ions, glucose, etc.
What is diffusion?
The movement of molecules from high concentration to low
How does osmosis relate to diffusion?
Osmosis is diffusion with water. Water moves from high concentration to low
Describe hypotonic solutions as they relate to red blood cells (HINT: solution in question is distilled water).
Water moves into RBC b/c of RBC’s lower water concentration causing it to burst
Describe isotonic solutions as they relate to normal RBCs.
The water concentration outside of the RBC is the same on the inside
Describe hypertonic solutions as they relate to RBCs (HINT: solution in question is saltwater).
Water moves out of RBC b/c of lower water concentration outside of cell
As it pertains to hypotonic, isotonic, and hypertonic solutions, what is the relationship between water and solute that causes water to move the way it does in osmosis?
Greater solute concentration = less water concentration, so water moves to where there is less water
