lecture 5: lipids Flashcards
General description of lipids + its 3 classes
- Relatively large molecules + structurally and functionally diverse
1. phospholipids
2. fats
3. steroids
What do lipids do? (7)
- Form biological membranes (phospholipids)
- Store chemical energy (fats)
- Insulates body + cushion vital organs in mammals
- Act as signalling molecules
- Aid in diverse processes in cells (means that they have a lot of other functions)
- Capture light energy (pigments in photosynthesis)
- Water proofing body structures (with hydrophobic part)
What does a lipid look like?
- Largely non-polar and hydrophobic bc major hydrocarbon component —> C-H —> high chemical energy bc of hilltop electrons that are loosely between molecules (low electronegativity)
Types of lipids found in cells (7)
- Fats
- Phospholipids
- Steroids
- Glycolipids
- Waxes
- Vitamins
- Photosynthetic pigments
Structure of fats
- Form via dehydration reactions
- 1 glycerol linked by ester linkages to 3 fatty acids —> not polymers bc can’t have infinite chains of it
Function of fat in animals (3)
- Long-term energy storage (short term = sugars) —> compact and bc animals have to move around
- Body insulation
- Cushion to protect vital organs
Function of fat in plants? In what form?
- In seeds: Protective + energy source for embryo (only in seeds bc plants don’t need fat as they don’t have to move)
- Liquid, oils at room temperature (olive oil, avocado oil) —> unsaturated fats
Difference between saturated and unsaturated fats
- Animal = saturated fats —> saturated fatty acids
- Saturated/filled completely with H
- Linear structure
- Bad for health
- More chemical energy than unsaturated - Plants = unsaturated fats —> unsaturated fatty acids
- NOT saturated with H —> DOUBLE BOND within chain
- Crooked/bends bc of double bond —> stays in liquid state bc more spaced out and more difficult to solidify
- Good for health
Phospholipid structure
- Polar (hydrophilic) head: glycerol, phosphate, polar/charged group
- Non polar (hydrophobic) tail: 2 fatty acids (all C-H bonds)
Function of phospholipids (2)
- Create biological membranes (plasma membrane, nuclear membrane) + cell’s internal compartments
- Involved in cell communication (cell signaling pathways)
Steroids structure
Polar/hydrophilic: R-group
Non polar/hydrophobic: Steroid rings + Isoprene chain (Chain of carbon)
- really different from phospholipid and fats
- mainly hydrophobic
3 functions of steroids + associated steroid?
- Cholesterol: precursor to make other steroids
- Cholesterol: structural molecules in animal cell membrane
- Testosterone, estradiol (estrogen): sex hormones, in cell to cell communication
What are hormones?
Functional class of molecules involved in cell-to-cell communication
Cholesterol (important precursor) can be used to make… (2)
- Steroid hormones: long-distance signaling molecules
- Bile acids (made in liver): help digest and absorb fats
What are glycolipids and sphingolipids?
Components of cell membrane and involved in cell communication
