[Unit 1.5] | Lipids Flashcards
List 4 roles of lipids.
• Energy sources
• Waterproofing
• Insulation
• Protection of delicate organs
What is a triglyceride comprised of?
• 1 Glycerol molecule
• 3 Fatty acids of variable length (-COOH)
What bonds form between the individual components of a triglyceride after a condensation reaction?
An ester bond (-COCO)
Why are triglyceride molecules useful for the storage of energy?
• Low mass:energy ratio so lots of energy can be stored in a small space.
• Insoluble so no impact on the water potential of a cell.
What is a saturated lipid?
A lipid where each carbon atom is bonded to 4 other atoms. They form regular arrangements and therefore molecules can lie closely to form solids at room temperature.
What is an unsaturated lipid?
A lipid where there is a C=C double bond which means the 2 carbons can only bond to 3 atoms. Molecules do not form a regular arrangement and have trouble lying close together, therefore forming liquids at room temperature.
What is the difference between a cis and a trans fat?
• Cis & trans fats are unsaturated, and they refer to the arrangement of the hydrogen atoms around the C=C double bond.
• A cis fat has 1 hydrogen atom for each carbon with both bonded on the same side (above or below the carbons).
• A trans fat has 1 hydrogen atom for each carbon with both bonded on different sides (one above ane one below).
What are the components of a phospholipid?
• 1 Glycerol molecule
• 2 Fatty acid chains of variable length (-COOH)
• 1 phosphate group
Describe the features of a phospholipid (head & tails).
• Head: Comprised of a glycerol molecule and a phosphate group. It is polar and hydrophillic.
• Tails: Consists of 2 fatty acid chains. It is non-polar and hydrophobic.
What are the stages of the lipid emulsion test?
• Add ethanol to sample and shake vigorously.
• Add water and shake gently.
• Observe a milky white emulsion if lipids are present.
