Lipids

• What is the fluid mosaic model?


  A model that describes the structure of cell membranes.
• How are carbohydrates incorporated in the cell membrane?


  They are attached to proteins and lipids on the extracellular surface.
• What is the function of carbohydrates in the cell membrane?


  They play a role in cell recognition and signaling.
• Compare the structure of glycogen and lactose.


  Glycogen is a branched polysaccharide, while lactose is a disaccharide.
• Which would cause a higher spike in blood sugar when eaten, glucose or starch? Explain your answer.


  Glucose would cause a higher spike because it is a simple sugar that is quickly absorbed.
• Why is there a large store of glycogen in our muscles?

  Glycogen serves as a readily available energy source during physical activity.
• Why can't starch diffuse across the cell membrane?


  Starch is a large polysaccharide that cannot pass through the lipid bilayer.
• Describe the structure of amylose and amylopectin.


  Amylose is a linear chain of glucose units, while amylopectin is branched.
• Describe the structure of starch and explain why this structure makes it a suitable molecule for storing energy.


  Starch consists of amylose and amylopectin, allowing for compact storage of glucose units.
• Explain the advantages of glycogen as an energy storage molecule in the human body.


  Glycogen can be rapidly mobilized for energy and is compactly stored in muscles and liver.
• Why is it useful for marathon runners to carb load before an event?


  Carb loading increases glycogen stores, providing more energy for endurance activities.
• What are lipids?


  A mixed group of non-polar, hydrophobic compounds composed of carbon, hydrogen, and oxygen.
• What role do lipids play in the body?


  They are involved in energy yield, energy storage, insulation, and hormonal communication.
• What are triglycerides?


  Triglycerides are a type of lipid that forms the main component of fats and oils.
• How are triglycerides formed?


  They are formed by esterification, where glycerol bonds with fatty acids.
• What is an ester bond?


  An ester bond forms when the hydroxyl group of glycerol bonds with the carboxyl group of a fatty acid.
• What type of reaction forms an ester bond?


  The formation of an ester bond is a condensation reaction.
• What is released for each ester bond formed?


  One water molecule is released for each ester bond formed.
• How many fatty acids join to one glycerol molecule to form a triglyceride?


  Three fatty acids join to one glycerol molecule.
• What is released when one triglyceride forms?


  Three water molecules are released when one triglyceride forms.
• Why are lipids insoluble in water?


  Because they are non-polar and hydrophobic compounds.
• Describe the structure of a triglyceride.


  A triglyceride consists of one glycerol molecule and three fatty acid chains.
• What bond is formed in a triglyceride?


  An ester bond is formed in a triglyceride.
• What are the products released from the hydrolysis of a triglyceride?


  Glycerol and fatty acids are released from the hydrolysis of a triglyceride.
• Describe the structure of a phospholipid.


  A phospholipid consists of a glycerol backbone, two fatty acid tails, and a phosphate group.
• Compare the structure of phospholipids with the structure of triglycerides.


  Phospholipids have two fatty acids and a phosphate group, while triglycerides have three fatty acids.
• Which substances can diffuse through the phospholipid bilayer?


  Small non-polar molecules can diffuse through the phospholipid bilayer.
• How do phospholipids interact with water?


  Phospholipids have hydrophilic heads that interact with water and hydrophobic tails that avoid it.
• Describe the structure of the cell membrane.

  The cell membrane is a phospholipid bilayer with embedded proteins and carbohydrates.
• Why would the pH in the small intestine change after lipase hydrolyzes lipids?


  The pH changes due to the release of fatty acids, which can lower the pH.
• What are saturated fatty acids?

  Saturated fatty acids contain the maximum number of hydrogen atoms and have no double bonds.
• Name two sources of saturated fats.

  Meat and dairy products are sources of saturated fats.
• What state are saturated fats typically found in?


  Saturated fats are typically solid at room temperature.
• Describe the structure of saturated fats.

  Saturated fats have long, straight hydrocarbon chains with single bonds.
• What is meant by a molecule's melting point?

  A molecule's melting point is the temperature at which it changes from solid to liquid.
• Why do saturated fats have high melting points?


  Saturated fats have high melting points due to strong intermolecular bonds between straight chains.
• What are monounsaturated fats?


  Monounsaturated fats contain one double bond in each fatty acid chain.
• What are polyunsaturated fats?

  Polyunsaturated fats contain multiple double bonds in their fatty acid chains.
• What state are unsaturated fats typically found in?


  Unsaturated fats are typically liquid at room temperature.
• What do carbon double bonds cause to happen in the hydrocarbon chain?


  Carbon double bonds cause kinks in the hydrocarbon chain, preventing tight packing.