UNIT 6: LIPIDS Flashcards
What are 3 main roles of lipids?
- energy source
- signalling
- precursor to hormones
A molecule with detergent characteristics means the _____ zone is strong. What does a detergent do?
hydrophilic zone strong of a amphipathic molecule
- destroys lipid structures to form emulsions
- destroys cell systems
What has a lower melting point?
Short chain FA or long chain FA
- short chain FA have lower melting points
What has a lower melting point?
saturated or unsaturated FA?
Unsaturated have lower melting points
saturated - straight chain - low fluidity - high melting point
Delta system nomenclature starts on which end?
Omega system?
Delta
- carbonyl (=O)
Omega
- methyl end (-CH3)
What are the only 2 essential fatty acids?
- Linoleic acid (LA, n-6)
- Alpha-linoleic acid (ALA, n-3)
Linoleic acid is metabolized to ____
Arachidonic acid (AA)
Alphalinoleic acid is metabolized to ____
eicosapentanoic acid (EPA) docosahexaenoic acid (DHA)
Linoleic acid and Alpha-linoleic acid can synthesize longer omega6 and omega 3 fatty acids via ___ and ___
desaturation and elongation, (and desaturation)
- products are AA, EPA, DHA
Increase in ______ increases fluidity of membranes
unsaturation
Eicosanoid signalling is essential in some endocrine pathways. What is eicosanoid formed from?
AA (essential eicosanoids)
EPA (nonessential eicosanoids)
What is the first step of eicosanoid signalling?
Enzyme phospholipid A-2 activtaes and release a free fatty AA (arachidonic acid) and EPA (eicosapentaenoic acid) from phospholipid membrane
= free fatty acid pool, important for synthesizing more eicosanoids and endocrine
What are the roles of free arachidonic acid (FFA) and eicosapentaenoic acid (EPA)?
- eicosanoid forming enzymes like lipoxygenases and cycloxygenases
- responses: disease resisting, wound healing,, inflammation
Proinflammatory events are catalyzed by what enzyme?
5-lipoxygenase
Prostoglandins that increase and decrease blood clotting, increase perception of pain/fever, asthma, incr. BP, catalyzed by what enzyme?
cycloxygenases COX
Eicosanoids are 20C metabolites of AA and EPA and have functions for:
inflammation, platelet aggregation
blood pressure
We ingest and store lipids mostly as ____?
Triglycerides (TG)
90% of dietary fats
What are the 3 classifications of lipids?
- triglycerides
- phospholipids
- sterols
Phospholipids are amphipathic, like triglycerides; but do not have _____ properties.
detergent
Do triglycerides have detergent properties?
- only the intermediate forms do
- monoacylglycerol MAG (1glycerol + 1FA)
- diacyglycerol DAG (1 glycerol + 2FA)
Phospholipids in the small intestine can become detergents for digestion by which process?
- clip sn-1 (the first) fatty acid (unsaturated)
- leaves the 2 (saturated) and 3 with phosphate
= 2-lysophospholipid (2lysoPL)
= now a detergent - but it needs to be converted back to a phospholipid once inside cells
What is the most prevalent phospholipid in the body?
phosphatidylcholine
PC
- choline attached to the phosphate at sn-3
What is a steroid nucleus?
the 4 ringed core structure that characterizes sterols and steroids
Most sterols are from diet than produced in the body. True / False
False. 60% endogenous, 40% diet
What vitamin is a sterol?
Vitamin D
