Lipids Flashcards
What elements do lipids contain?
Carbon, hydrogen, and oxygen
Are lipids soluble in water?
No, lipids are insoluble in water
In what type of solvents are lipids soluble?
Organic solvents, e.g., alcohol
Name two types of lipids.
Triglycerides and phospholipids
What is the structure of a triglyceride molecule?
3 fatty acids joined to one glycerol molecule
How are fatty acids joined to glycerol in triglycerides?
Through three condensation reactions with the loss of three water molecules
What type of bond forms between glycerol and a fatty acid?
Ester bond
How many ester bonds are present in one triglyceride molecule?
3 ester bonds
Are triglycerides and phospholipids considered polymers?
No, they are not polymers
What is the general formula of a fatty acid?
R-COOH
What does ‘R’ represent in the fatty acid formula?
A long hydrocarbon chain
What is the characteristic of saturated fatty acids?
No double bonds between the carbon atoms
What defines unsaturated fatty acids?
One or more double bonds between the carbon atoms
What is a method to hydrolyze lipids?
Heating or using water
What type of group is present in phospholipids?
Phosphate group
Fill in the blank: The R group in fatty acids can vary, leading to different types of _______.
Fatty acids
True or False: Triglycerides are made up of similar monomers.
False
What happens during the condensation reaction forming triglycerides?
Loss of water molecules
What type of reaction is involved in the formation of an ester bond?
Condensation reaction
What are lipids soluble in?
Lipids are soluble in organic solvents.
Lipids do not dissolve in water.
What process hydrolyzes lipids into fatty acids and glycerol?
Hydrolysis of lipids can occur by heating with acid or alkali or using the enzyme lipase.
The hydrolysis process involves breaking ester bonds.
What is the energy release comparison between triglycerides and carbohydrates during aerobic respiration?
Triglycerides release twice as much energy as carbohydrates.
This is due to their high proportion of carbon-hydrogen bonds.
What is metabolic water and why is it important for organisms in dry deserts?
Metabolic water is released when triglycerides are respired, important for hydration in dry environments.
It results from the high ratio of hydrogen to oxygen in triglycerides.
Why are triglycerides considered ideal storage compounds?
Triglycerides are non-polar and insoluble in water, making them osmotically inactive.
This property prevents water retention in cells.
Where are triglycerides present that helps reduce water loss?
Triglycerides are present in the waxy cuticle of insects and plant leaves.
Their insolubility helps minimize evaporation.
What do phospholipids contain that distinguishes them from other lipids?
Phospholipids contain a phosphate group.
This characteristic differentiates them from triglycerides.
What components make up a phospholipid molecule?
A phospholipid molecule consists of one glycerol, two fatty acids, and a phosphate group.
These components are joined by condensation reactions forming ester bonds.
What is the structure of the phospholipid molecule?
The phospholipid molecule has a polar hydrophilic head and a non-polar hydrophobic tail.
The head attracts water, while the tail repels it.
Fill in the blank: A phospholipid consists of a glycerol, two fatty acids, and a _______.
phosphate group.
True or False: Phospholipids are soluble in water.
False.
The hydrophobic tail of phospholipids makes them insoluble in water.
What is the structure of phospholipids in cell membranes?
They form a bilayer due to hydrophobic tails being repelled by water.
What is the emulsion test used for?
To detect lipids in a sample.
What are the steps involved in the emulsion test for lipids?
- Place a small amount of the sample into a test tube with ethanol
- Shake the mixture to dissolve the fat
- Add the mixture to water in another test tube and mix
- A white emulsion of fat droplets indicates lipid presence.
What are the common characteristics of both triglycerides and phospholipids?
- Insoluble in water
- Contain glycerol
- Contain ester bonds
- Contain C, H, and O
- Phospholipids also contain P
How many fatty acids are present in triglycerides and phospholipids?
Triglycerides have three fatty acids; phospholipids have two fatty acids plus a phosphate group.
What is the polarity of triglycerides and phospholipids?
- Triglycerides are hydrophobic/non-polar
- Phospholipids have hydrophilic and hydrophobic regions.
