8. Lipids Flashcards
major types of dietary lipids
fatty acids
- saturated fats
- mono/polyunsaturated fats
- trans fats
Sterols
- triglycerides
- phospholipids
omega fatty acid naming
- small w-ish thing (look at pg 6)
- position of first double bond from methyl end
linoleic acid naming
- delta sign (ex: cis-delta^9)
- each double bond is indicated by a delta sign and a number
begins from carboxylic acid side - omega-6
What is the starting material for fatty acid synthesis?
Acetyl-CoA
What are the steps in fatty acid synthesis? What enzyme is responsible for this process?
- it’s a series of cytosolic reactions beginning with Acetyl-CoA and resulting in Malonyl-CoA
- Acetyl-CoA carboxylase and fatty acid synthase are enzymes responsible for process
Essential Fatty Acids
- the body doesn’t produce them but they are required for metabolism
- humans don’t have delta 12 and delta 15 desaturase (linoleic and linolenic acids are essential fatty acids)
Health benefits of EPA and DHA
They’re linked to healthy aging throughout life (omega-3 fatty acids)
Why is it hard for Americans to get sufficient amounts of EPA and DHA?
The best source is fish, but a lot of Americans don’t eat fish
Arachidonic Acid
- 20 carbon, omega-6 fatty acid
- important in the function of the brain, liver, and muscles
- involved in regulation of signaling enzymes
Eicosanoids
Signaling molecules made by the oxidation of twenty carbon essential fatty acids
- control inflammation and immunity
- CNS messengers
- Derived from omega 3 and 6 EPA’s
Cyclooxygenase
what kind of drugs affect it
Enzyme responsible for the formation of prostanoids
- subclass of eicosanoids
- NSAIDS like ASPIRIN inhibit this enzyme to reduce inflammation
Triglyceride components
3 fatty acids bonded to a glycerol backbone via ester bonds
Phospholipid components
2 fatty acids and a phosphate group bonded to a glycerol backbone
- found in membranes due to their bilayer formation
What is the starting material for cholesterol synthesis?
Acetyl-CoA
What is the rate limiting step in cholesterol synthesis?
The HMG-CoA Reductase reaction (HMG-CoA is a rate limiting enzyme)
Lipitor
Statin drug that inhibits HMG-CoA reductase (rate limiting enzyme in cholesterol synthesis)
What is the major enzyme involved in triglyceride digestion?
Pancreatic lipase
- hydrolyzes and cleaves the fatty acids from the glycerol in triglyceride digestion
Function of bile salts and where do they come from
- they form mycelles which help solubilize lipids to aid in absorption
- made by the liver, and stored in the gall bladder
What is beta-oxidation and where does it occur?
- the process of fatty acid oxidation
- occurs in the mitochondria
- breaks fatty acids down into Acetyl-CoA
- produces NADH+H and FADH
What are Ketone Bodies? When are they formed, and what’s their role?
- produced during atypical metabolic scenarios (uncontrolled diabetes, pregnancy, starvation)
- formed from oxidation of fatty acids and the conversion of amino acids
- provide source of energy for the body
Why do people with high ketone bodies have bad breath?
- a product of ketone bodies is acetone formation
- this is then volatilized in the lungs and expired
Why do people with uncontrolled Type I diabetes have high levels of ketone bodies?
- type 1 diabetes produces high levels of ketone bodies (because their insulin levels are too low to transport glucose)
- means they have to get energy from a different source
- causes production of lots of ketone bodies
Ketoacidosis symptoms
- bad breath (from acetone production)
- High blood glucose levels
- High ketone levels in urine
- thirst and dry mouth
- frequent urination
- tired feeling
- dry or flushed skin
- hard time breathing
- lack of attention
Lipoprotein components
- made up of proteins and lipids (typically cholesterol)
- allows fats to move through water inside and outside the cells
- They’re lipid emulsifiers
Chylomicron (lipoprotein)
- absorb diet-derived triglycerides and cholesterol
- transports them into the blood
VLDL (lipoprotein)
- transports dietary lipids from the intestines to other locations in the body
- produced in the liver to transport endogenously produced triglycerides and cholesterol to the peripheral tissues
IDL (lipoprotein)
- found in blood stream
- aids in transport of triglycerides and cholesterol around the body
HDL (lipoprotein)
- produced in liver
- transports cholesterol to the liver from the body
LDL (lipoprotein)
- transports cholesterol to the arteries and the rest of the body
Role of LDL cholesterol in atherosclerosis?
LDL is the transport that leaves the cholesterol and triglyceride accumulated on the artery walls (causing atherosclerosis)
What is a foam cell?
macrophages which have engulfed large amounts of fatty substances (usually cholesterol)
Why does atherosclerosis kill you?
- causes lesions in the main arteries of the body
- cause closure of the lumen, which then causes the blood supply to weaken and become insufficient
- full arterial blockage can be lethal
Why is HDL-cholesterol “good” cholesterol?
- it takes cholesterol and fatty-acids from your arteries back to your liver
- prevents heart attacks and plaque buildup
Recommendations for fat
- avoid trans fats completely
- limit cholesterol to 200-300 mg per day
- consume less than 10 percent calories from sat fat
- keep total fat between 20-35 percent of total calories
Diet-Health Hypothesis
sat fat raises blood cholesterol which then raises chance for a heart attack
What are the metabolic effects of consuming too many trans fats?
- raises LDL and lowers HDL
- raises risk of coronary heart disease
