BIOL 2255 EXAM 2 CORE BIOLOGY CONCEPTS REVIEW 2026

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