BIOL 2255 EXAM 2 CORE BIOLOGY
CONCEPTS REVIEW 2026
◉ key functions of lipids.
Answer: makes up cell membrane, energy storage
◉ 2 primary functions of the cell membrane.
Answer: 1. define cell boundary
2. regulation of molecules
◉ main components of the cell membrane.
Answer: - lipids
- proteins
- carbohydrates
◉ what contributes to the fluidity of a membrane?.
Answer: lipid types & characteristics of fatty acid chains
◉ amphipathic.
Answer: having both hydrophilic & hydrophobic regions
,◉ which part of a phospholipid is hydrophilic?.
Answer: head
◉ which part of a phospholipid is hydrophobic?.
Answer: fatty acid tails
◉ main function of a phospholipid.
Answer: forms the cell membrane
◉ lipid bilayer.
Answer: 2 layers of lipids
◉ which part of the phospholipid is tucked inside the membrane?.
Answer: nonpolar, hydrophobic tail
◉ why is the polar part of the phospholipid facing outward?.
Answer: can form bonds
◉ liposome.
Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
, ◉ why is pH important?.
Answer: ensures polar head is in ionized form--makes them
hydrophilic
◉ van der Waals forces.
Answer: weak binding of temporarily polarized molecules due to
attraction of opposite charges
- helps w/ sticking of cholesterol/phospholipids in a cell membrane
◉ saturated fats.
Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
◉ unsaturated fats.
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol.
Answer: makes up 30% of cell membrane
CONCEPTS REVIEW 2026
◉ key functions of lipids.
Answer: makes up cell membrane, energy storage
◉ 2 primary functions of the cell membrane.
Answer: 1. define cell boundary
2. regulation of molecules
◉ main components of the cell membrane.
Answer: - lipids
- proteins
- carbohydrates
◉ what contributes to the fluidity of a membrane?.
Answer: lipid types & characteristics of fatty acid chains
◉ amphipathic.
Answer: having both hydrophilic & hydrophobic regions
,◉ which part of a phospholipid is hydrophilic?.
Answer: head
◉ which part of a phospholipid is hydrophobic?.
Answer: fatty acid tails
◉ main function of a phospholipid.
Answer: forms the cell membrane
◉ lipid bilayer.
Answer: 2 layers of lipids
◉ which part of the phospholipid is tucked inside the membrane?.
Answer: nonpolar, hydrophobic tail
◉ why is the polar part of the phospholipid facing outward?.
Answer: can form bonds
◉ liposome.
Answer: spherical bilayer structure
- forms in aqueous environment at neutral pH
, ◉ why is pH important?.
Answer: ensures polar head is in ionized form--makes them
hydrophilic
◉ van der Waals forces.
Answer: weak binding of temporarily polarized molecules due to
attraction of opposite charges
- helps w/ sticking of cholesterol/phospholipids in a cell membrane
◉ saturated fats.
Answer: - NO carbon=carbon double bonds
- straight structure
- tight packing --> reduces mobility (fluidity)
◉ unsaturated fats.
Answer: - carbon=carbon double bonds
- kinked structure
- reduced tightness of packing --> enhances mobility (fluidity)
◉ cholesterol.
Answer: makes up 30% of cell membrane
