Week 10: Lipids And Membranes Flashcards
What are lipids characterized by?
Low solubility in water (hydrophobic molecules)
Lipids are structurally diverse organic molecules.
What are the primary functions of lipids?
- Storage lipids are important fuels
- Insulation from environment
- Membrane lipids are important components of cellular membranes
What are fatty acids?
Carboxylic acids with hydrocarbon chains containing between 4 to 36 carbons
16 or 18 carbons are the most common.
What is the common structure of saturated fatty acids?
No double bonds between carbons in the chain
What distinguishes unsaturated fatty acids?
One or more double bond(s) between carbons in the chain
What are the two types of unsaturated fatty acids?
- Monounsaturated: one double bond
- Polyunsaturated: more than one double bond
How do saturated and unsaturated fatty acids differ in packing?
- Saturated fatty acids pack in a fairly orderly way
- Unsaturated cis fatty acids pack less orderly due to the kink
What is the melting point difference between saturated and unsaturated fatty acids?
Saturated fatty acids have a higher melting point
What is the typical structure of triacylglycerols (TAGs)?
Glycerol and three fatty acids
What are the common types of membrane lipids?
- Glycerophospholipids
- Sphingolipids
- Cholesterol
What is the structure of glycerophospholipids?
Glycerol, two fatty acids, and a phosphorylated alcohol
What distinguishes sphingolipids from glycerophospholipids?
The backbone of sphingolipids is sphingosine instead of glycerol
What is the steroid nucleus structure of cholesterol?
Four fused rings
What are the five major classes of steroid hormones?
- Androgens
- Estrogens
- Progestogens
- Glucocorticoids
- Mineral corticoids
What are the lipid-soluble vitamins?
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
What is the primary composition of membranes?
A variety of lipids and proteins
What is the fluid mosaic model?
Membrane lipids and proteins can diffuse laterally
What factors influence membrane fluidity?
- Content of unsaturated fatty acids
- Cholesterol content
What is membrane asymmetry?
Membrane lipids can diffuse laterally but not from one leaflet to another
Fill in the blank: Triacylglycerols (TAGs) are the _______ form of lipids.
Storage
True or False: Most vitamins can be synthesized by humans.
False
What are the roles of biologically active lipids?
Signaling molecules e.g. steroid hormones
What are some functions of membrane proteins?
- Pumps
- Channels
- Receptors
- Enzymes
What is the significance of the double bonds in unsaturated fatty acids?
They are commonly in cis configuration, which kinks the chain
