BIOC 212 Lecture Notes - Lecture 51: Cardiolipin, Cytosol, Inner Membrane
29 May 2018
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Department
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Metabolism XIII
Fatty Acids Stored as Triglycerides
• Fats are the other major metabolic storage compartment for energy
o In animals, most of the energy that you use is stored as fat and not glycogen
o Glycogen is really a chemical buffering system for the blood
o But for ability to wake up in the middle of the night after not eating for 10
hours and fight off a bear, energy to replenish comes from burning fats
• Adipose tissues are the repository for fat storage in mammals
o Fats are stored in specialized tissues called adipose tissues
o Fat cells respond to extracellular hormones, including insulin & other steroid
hormones to breakdown fats when general energetic requirements in the
body need to be met
• Free fatty acids are incorporated into molecule of triglyceride
o Glycerol backbone with 3 fatty acid tails instead of 2
• In fat cells, these are stored in large aggregates
o Cell is made of a bit of cytoplasm, a nucleus and a ton of fat aggregate
• Hydrolyzed from glycerol backbone to fatty acids for release
o When need to release into the bloodstream, the free fatty acids are
hydrolyzed from glycerol
o Are bound by carrier proteins to solubilize them in the cytoplasm & blood
o Taken up by cells that have active metabolic requirements
• Enter mt; undergo beta oxidation to get broken down and produce
energy
• Or can be absorbed by cells that need to use them for anabolic
metabolism
• Release into bloodstream is also tightly controlled by metabolic hormones
Chloroplasts Store Starch & Fat in Plants
• In plants, works differently --rely less on systemic metabolic reservoir and instead
have lots local storage in starch
o Starch is the plant glucose polysaccharide reserve
o When individual cells run low on energy, they can funnel this energy straight
into the mt for energetic requirements
• Chloroplasts are specialized double-membraned organelles with their own
genome, like mitochondria
o Chloroplasts are larger than mitochondria
o Incorporate the anabolic photosynthesis machinery & storage of many of
products of those reactions until needed to be used
Document Summary
Fatty acids stored as triglycerides: fats are the other major metabolic storage compartment for energy. Incorporate the anabolic photosynthesis machinery & storage of many of products of those reactions until needed to be used. In plants, chloroplasts store starches and fat when it is not needed for atp production in mitochondria. Chloroplasts generate all metabolic substrates: shuttles that take all local energetics requirements from chloroplasts and use them in the mt to generate atp. If synthesizing a molecule of glucose, uses 6 co2 from the atmosphere: then shuttle it to the mt where broken down by glycolytic pathway and citric acid cycle, convert it straight back to co2. Co2 straight back into the atmosphere and generate energy in the plant: or used to feed the entire biosphere. Inner membrane: completely impermeable, even to protons: has controlled permeability to electrons, any molecules or ions dissolved in water cannot cross, rich in cardiolipins (specialized lipids)
